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Showing papers in "Journal of Astm International in 2004"


Journal ArticleDOI
TL;DR: The authors explored the Paris equation relating crack growth rate and applied stress intensity to illustrate many statistical realities that are often ignored by otherwise careful engineers, including Monte Carlo and fast probability integration methods.
Abstract: Many engineers effect “probabilistic life prediction” by replacing constants with probability distributions and carefully modeling the physical relationships among the parameters. Surprisingly, the statistical relationships among the “constants” are often given short shrift, if not ignored altogether. Few recognize that while this simple substitution of distributions for constants will indeed produce a nondeterministic result, the corresponding “probabilities” are often woefully inaccurate. In fact, even the “trend” can be wrong, so these results can't even be used for sensitivity studies. This paper explores the familiar Paris equation relating crack growth rate and applied stress intensity to illustrate many statistical realities that are often ignored by otherwise careful engineers. Although the examples are Monte Carlo, the lessons also apply to other methods of probabilistic life prediction, including FORM/SORM (First/Second Order Reliability Method) and related “fast probability integration” methods.

70 citations


Book ChapterDOI
C.M. Sonsino1
TL;DR: In this paper, the authors demonstrate the need for experimental spectrum tests, which are indispensable for ensuring the safety of parts, by considering the failure probability resulting from the probability of occurrence of the spectrum, from the scattering of the fatigue strength and from the failure criterion (technical crack or propagation).
Abstract: The proper consideration of variable amplitude loading by utilizing service spectra and appropriate Gassner-lines is essential for the design of light-weight components and structures by allowing loads in significant excess of the Woehler-line (S-N curve). This permits higher stresses than under constant amplitude loading and renders reduced component dimensions. Reliable reconstitution and simulation methods for service load-time histories require not only the rainflow matrices, but also information about the order of the cycles described by Markovian matrices, the power spectral density and, for multiaxial applications, the cross-correlations between the particular load directions as well as the phase relations. A major problem in numerical fatigue life assessment is still the fatigue life calculations for spectrum loading, because of the scattering of the real damage sum D over a wide range, which is not entirely understood. These findings demonstrate the need for experimental spectrum tests, which are indispensable for ensuring the safety of parts. With regard to safety and liability requirements, the failure probability resulting from the probability of occurrence of the spectrum, from the scattering of the fatigue strength and from the failure criterion (technical crack or propagation), must be taken into account.

58 citations


Journal ArticleDOI
TL;DR: In this article, an enhanced life management process based on probabilistic damage tolerance methods has been developed to address material anomalies in titanium rotating components of gas turbine engines, which are used as tools to investigate the impact of engine monitoring and usage variability on prognosis for field readiness and life management.
Abstract: An enhanced life management process based on probabilistic damage tolerance methods has been developed to address material anomalies in titanium rotating components of gas turbine engines. Related methods are being used as tools to investigate the impact of engine monitoring and usage variability on prognosis for field readiness and life management. This paper begins with an overview of the process of probabilistic damage tolerant design, using the DARWIN® computer program to illustrate the interplay between various random variables and the conventional elements of structural design and life prediction. Special attention is then given to the initial distribution of material anomalies, scatter in fatigue crack growth data, and variability in complex mission histories. The significance of each source of variability for different applications is discussed.

40 citations


Journal ArticleDOI
TL;DR: The extrapolating methodology is extended to combine data from several users to obtain loading spectra that represent more severe users in the population.
Abstract: This paper describes a methodology for statistically extrapolating a single measured service loading history to the expected long-term service usage spectra. The measured time history first is processed into a rainflow counted histogram. Nonparametric kernel smoothing techniques are employed to convert the rainflow histogram of cycles into a probability density histogram. Once the probability density histogram is obtained, Monte Carlo methods are used to produce a rainflow histogram of any desired number of cycles. A new loading history then is reconstructed from the expected rainflow histogram, which can be combined with a probabilistic fatigue analysis to obtain an estimate of the durability of a structure. Obtaining an estimate of the loading spectra for a ground vehicle is difficult because there are many users, each with different service usage. The extrapolating methodology is extended to combine data from several users to obtain loading spectra that represent more severe users in the population.

40 citations


Journal ArticleDOI
TL;DR: Four Ultra-High Molecular Weight Polyethylene materials were evaluated after various irradiation crosslinking processes to determine the effects of the materials and processes on their properties for orthopaedic applications and wear testing indicated that there was a direct correlation with irradiation dose but not with the crosslink density.
Abstract: Four Ultra-High Molecular Weight Polyethylene (UHMWPE) materials were evaluated after various irradiation crosslinking processes to determine the effects of the materials and processes on their properties for orthopaedic applications. The materials and processes included two molecular weight materials (GUR 1020 and GUR 1050), two fabricated forms (ram extruded bar and compression-molded sheet), two irradiation sources (gamma and e-beam) and multiple irradiation doses ranging from 30–120 kGy. Increasing irradiation dose led to increased crosslinking, decreased wear, and decreased toughness. The molecular weight of the starting material and the irradiation source both had effects on the final properties while the fabricated form did not. Wear testing of selected groups indicated that there was a direct correlation with irradiation dose but not with the crosslink density (as calculated from the swell ratio).

35 citations


Journal ArticleDOI
TL;DR: There are several standards that require the use of a hot plate apparatus for measuring the dry thermal resistance (insulation) and the evaporative resistance of fabrics: ASTM D 1518, ASTM F 1868, and ISO 11092.
Abstract: There are several standards that require the use of a hot plate apparatus for measuring the dry thermal resistance (insulation) and the evaporative resistance of fabrics: ASTM D 1518, ASTM F 1868, and ISO 11092. In addition, several National Fire Protection Association standards for protective clothing (NFPA 1951, 1971, 1977, and 1999) specify the use of this method. All of these methods measure the total resistance (i.e., the resistance of the fabric and the resistance of the surface air layer). The resistance of the air layer alone is determined by conducting a “bare plate” test. This air layer resistance is often subtracted from the total resistance to determine the fabric resistance values. Different standards use different terms for these resistances (Ret or Ref), and they report the resistances in different units (m2 · kPa/W or m2 · Pa/W). In addition, some methods call for guarded plates, whereas others use smaller plates, for which the experimenter must adjust the data for thick specimens to compensate for the lack of a guard. Some methods control the air velocity over the specimen, while others allow any air speed, as long as the calibration requirements on standard fabrics are met. This paper discusses the differences in test instruments, conditions, measured parameters, and units so that data from different labs can be compared and understood. In addition, data from an ASTM interlaboratory study is presented so that the repeatability and reproducibility of the different test protocols on a variety of materials can be discussed.

33 citations


Journal ArticleDOI
TL;DR: In this paper, a study was conducted to determine how the unconfined compressive strength and flow of flowable fills prepared with foundry sand depends on the bentonite content of the sand.
Abstract: A study was conducted to determine how the unconfined compressive strength and flow of flowable fills prepared with foundry sand depends on the bentonite content of the sand. The study showed that there are several advantages of using foundry sands with bentonite content > 6% as the fine aggregate in flowable fill. These advantages include: (i) lower long-term strength gain (making the design of excavatable mixtures simpler and less risky), (ii) less flow loss, (iii) fewer components and fewer interactions between components that are difficult to characterize, and (iv) a larger fraction of inexpensive foundry sand being used in the mixture. The unconfined compressive strength (UCS) of flowable fills prepared with foundry sands is sensitive to the water-cement ratio (W/C), at least when the W/C spans a broad range (4–11). Mixtures with W/C 6.5. Bentonite content does not affect the UCS systematically, but it does have an indirect effect in that foundry sands with more bentonite require more water to flow, which affects strength. The amount of water required to achieve adequate flow primarily is a function of the bentonite content of the foundry sand. In general, as the bentonite content of the foundry sand increases, the water content of the mixture should increase correspondingly. The amount of fly ash has only a modest effect on the amount of water required. The most important factor affecting flow loss is the presence of cementitious fly ash in the mixture. Flow loss can be reduced appreciably by using a foundry sand with at least 6% bentonite so that fly ash fines need not be added to the mixture.

30 citations


Journal ArticleDOI
TL;DR: In this paper, the microstructural changes caused by neutron irradiation have been characterized in A508 Grade (Gr) 4N-type steels using a variety of state-of-the-art analytical techniques including 3D-Atom Probe Field-Ion Microscopy and Small Angle Neutron Scattering, along with post-irradiation annealing studies combining Positron Annihilation Lineshape Analysis and hardness measurements.
Abstract: Neutron irradiation can promote significant changes in the microstructure and associated mechanical properties of low alloy steels. In particular, irradiation can induce the formation of non-equilibrium phases and segregation, which may lead to a degradation in toughness. In this study, the microstructural changes caused by neutron irradiation have been characterized in A508 Grade (Gr) 4N-type steels ({approx}3.5% Ni) using a variety of state-of-the-art analytical techniques including 3D-Atom Probe Field-Ion Microscopy and Small Angle Neutron Scattering, along with post-irradiation annealing studies combining Positron Annihilation Lineshape Analysis and hardness measurements. Important differences between conventional and ''superclean'' A508 Gr 4N steel have been identified in this investigation. The data indicate that Ni is not the controlling factor in the irradiation damage behavior of these materials; rather, the Mn content of the steel is a dominant factor in the irradiation-induced microstructural development of solute-related hardening features.

29 citations


Journal ArticleDOI
TL;DR: The key mechanical property that was positively identified to correlate with the structural fatigue performance of crosslinked polyethylene materials was the ultimate tensile strength, whereas tensile elongation within 250% and 400% range had no effect on structural integrity.
Abstract: There have been increasing concerns about the structural fatigue resistance of crosslinked UHMWPE devices due to deterioration of certain mechanical properties. However, due to the lack of clear correlation between specific mechanical properties and clinical performance, these concerns remain theoretical. In order to evaluate the potential benefits and risks of various crosslinked polyethylene materials for hip and knee bearing applications, two clinically relevant worst-case scenarios were simulated on functional devices. In the first worst-case scenario, cemented all-poly patellar components were tested under simulated stair-climbing conditions with rotational misalignment. In the second worst-case scenario, metal-backed thin acetabular liners were tested in a hip joint simulator under rim-loading conditions. Various types of crosslinked UHMWPE were prepared according to published process descriptions of commercial materials. While significant levels of volumetric wear reduction were confirmed by both the patellar and hip simulator tests, mixed results were obtained on the structural integrity of the devices. The latter was more significantly affected by the post-irradiation thermal treatment history than by the total dose of irradiation. Re-melting following irradiation led to catastrophic fractures of both rim-loaded liners and rotational-malaligned patellar pegs. The key mechanical property that was positively identified to correlate with the structural fatigue performance of crosslinked polyethylene materials was the ultimate tensile strength, whereas tensile elongation within 250% and 400% range had no effect on structural integrity. However, the results presented in this study should not be misconstrued with respect to the potential clinical performance of irradiation crosslinked and re-melted polyethylene liners with proper designs. In fact, the true outcome of all the crosslinked materials can only be revealed by long-term clinical follow-up.

28 citations


Journal ArticleDOI
TL;DR: In this paper, the authors used the concept of Impedance Spectroscopy (IS) to measure the electrical conductivity of soil in the 20 Hz to 1 MHz frequency range.
Abstract: Electrical conductivity of soils has been demonstrated to be an important parameter for determining their basic properties. As measurement of soil conductivity using the DC field is limited by irreversible changes in the state of the soil and the errors due to electrode polarization, application of an AC field has been recommended. However, it has been noted that researchers have resorted to the ‘single frequency measurements’, considering that impedance is purely resistive, which may not always be true. Hence, it becomes essential to study electrical conductivity of soils in a broad frequency range. With this in view, using the concept of Impedance Spectroscopy (IS), conductivity measurements were carried out on different type of soils in the 20 Hz to 1 MHz frequency range, and details of the study are presented in this paper. Measured data has also been analyzed using Nyquist and Bode formats, and a good matching of the results has been noted. This demonstrates utility of the developed methodology and the ease with which electrical conductivity of soils can be determined in the laboratory.

26 citations


Journal ArticleDOI
TL;DR: In this paper, the burn off test in ASTM D 3171-99 was extended to characterize carbon/glass hybrid composites, and data were obtained for a series of samples with known compositions.
Abstract: Hybrid composites are increasingly being used in infrastructure, oil recovery, and aerospace applications. These hybrids generally combine two different types of fibers to reinforce the resin, thereby gaining some of the advantageous properties of both fibers. Typically, carbon and glass are used since this combines the high performance of the carbon with the low cost of the glass. The performance of such materials depends on a number of factors, including the mix ratio of the fibers as well as the fiber and void contents. At present, there is no simple way to determine these features. Although a number of techniques exist for measuring such parameters when only a single reinforcement is present, extension of these methods to hybrids can be difficult. The work here, however, shows that one technique, the burn off test in ASTM D 3171-99, can be extended to characterize carbon/glass hybrids. To verify this procedure, data were obtained for a series of samples with known compositions, and the agreement was excellent. The proposed method has minimal equipment requirements and provides a simple way to obtain important compositional information.

Journal ArticleDOI
TL;DR: In this article, the effect of neutron flux level on radiation-induced embrittlement in pressure vessel (RPV) steels is investigated, and the results of the analysis are consistent with a modest effect of flux on embrittlements.
Abstract: The effect of neutron flux level is a longstanding concern for determining the applicability of test reactor data or high lead-factor surveillance data to the prediction of embrittlement in commercial reactor pressure vessels (RPV). However, as operating reactors reach higher fluences, the question of flux effects is becoming increasingly relevant for situations such as embrittlement attenuation through the (RPV) and the comparison of boiling and pressurized reactor RPVs. In spite of its technological importance and extensive experimental and theoretical investigation, the issue of neutron flux effects on radiation-induced embrittlement in RPV steels remains unresolved. For neutron fluxes much greater than RPV operating conditions (>100 times higher), a regime exists in which the effects of flux are well defined experimentally and are well predicted by current models. These same models predict that the effect of flux should be relatively weak for values near those obtained in commercial RPVs, but may increase at lower fluxes. However, it is difficult to obtain sufficient data at low to intermediate fluxes to unambiguously determine the effects of flux since the time required to reach the desired fluences is necessarily long. In order to demonstrate the potential effects of flux on RPV embrittlement, and to help interpret the available experiments, a kinetic embrittlement model has been used in an analysis of the primary variables involved. The results of the analysis are consistent with a modest effect of flux on embrittlement for fluxes near those typical of commercial RPVs.

Journal ArticleDOI
TL;DR: In this article, a series of small-scale laboratory experiments were developed in an effort to simulate the hydraulic and thermal conditions existing at the base of a landfill, as well as potential impacts on the performance of the geosynthetic clay liner.
Abstract: Composite liners comprised of geomembranes and geosynthetic clay liners can be an effective means of minimizing fluid flow and associated groundwater contamination from municipal solid waste landfills. There remains uncertainty, however, regarding the long-term performance of such systems under conditions of elevated temperature that may occur at the base of landfills attributable to exothermic waste degradation processes. The heat generated by these processes may lead to the development of a thermal gradient through the lining system that creates a risk of desiccation within the uppermost portion of the subsoil and the geosynthetic clay liner itself. To investigate this issue, a series of small-scale laboratory experiments were developed in an effort to simulate the hydraulic and thermal conditions existing at the base of a landfill. This paper presents the results of investigations into the influence of various parameters on the behavior of a composite liner. The distribution of temperature and water content over time is discussed, as well as potential impacts on the performance of the geosynthetic clay liner.

Journal ArticleDOI
TL;DR: In this article, the authors measured the thermal resistance (insulation) and evaporative resistance of a variety of sports ensembles worn for football, basketball, baseball, soccer, track, tennis, golf, and cycling.
Abstract: The protective clothing and equipment required for certain sports may inhibit heat loss from the body and contribute to potentially harmful heat stress injuries. This study measured the thermal resistance (insulation) and evaporative resistance of a variety of sports ensembles worn for football, basketball, baseball, soccer, track, tennis, golf, and cycling. The thermal resistance was measured with a heated sweating manikin in an environmental chamber according to ASTM F 1291. The intrinsic insulation values (Rcl) ranged from a low of 0.018 m2.0 C/W for running/aerobic ensemble consisting of a sports bra and compression shorts to 0.152 m2.0 C/W for a football uniform. The intrinsic evaporative resistance values (Rccl) ranged from 0.004–0.028 m2kPa/W for the same ensembles, respectively. Sports uniforms that cover a large portion of the body surface or provide impact protection substantially reduced heat loss from the body. The data presented in this paper can be used in the solution of heat balance equations to predict physiological responses of athletes when wearing uniforms under different conditions.

Journal ArticleDOI
TL;DR: In this article, the effects of introducing body checking at the Atom age level were investigated using an experimental design in which teams from the Ottawa District Minor Hockey Association (ODMHA) represented the control group, while teams from Ontario Hockey Federation represented the treatment group, over a 3-year period from 1998 to 2001.
Abstract: The purpose of this study was to determine the effects of initiating body checking at the Atom age level The study used an experimental design in which teams from the Ottawa District Minor Hockey Association (ODMHA) represented the control group, while teams from the Ontario Hockey Federation (OHF) represented the treatment group The study was conducted over a 3-year period from 1998 to 2001 The comparison sampling between the two leagues was as follows: ODMHA Yr1 = 69 teams versus OHF Yr1 = 74 teams, ODMHA Yr2 = 59 teams versus OHF Yr2 = 101 teams, ODMHA Yr3 = 46 teams versus OHF Yr3 = 90 teams Measures of interest reported here included player selection bias, injury incidence, and variables that describe the characteristics of the flow of the game such as goals for, goals against, and number of penalties Athlete exposures for each league by year were computed using 15 players per team for a 20 game plus 20 practice schedule Statistical analysis of the difference in proportions of injuries reported by the two leagues based on the CHA injury insurance dataset showed that no significant difference occurred per year of the study In addition, the rates of injuries were lower in each year than those reported by previously published studies Body checking, which includes body contact is considered by many to be a skill within the game of ice hockey that can be taught at the younger age levels in a manner that does not lead to a higher incidence of injuries, or unfavorable changes in the game The results of this study support that contention In the present study, it was assumed that education was an essential component of the introduction process and that coaches were provided the necessary background to enable them to teach the introduction of body checking as a skill

Journal ArticleDOI
TL;DR: A range of techniques has been examined in relation to key measurements such as pore size and porosity, although capillary flow porometry measures a pore solely at its most constricted point, the method is unable to provide characterisation of other aspects of the pore.
Abstract: Tissue engineering involves seeding the patient's cells on to a three-dimensional temporary scaffold It is becoming increasingly obvious that cells used to seed the scaffold have very specific requirements concerning the morphology and chemistry of the surface of the scaffold and its interconnectivity A range of techniques has been examined in relation to key measurements such as pore size and porosity Since capillary flow porometry measures a pore solely at its most constricted point, the method is unable to provide characterisation of other aspects of the pore Scanning Electron Microscopy is limited to examining surface pores in ‘stiff’ scaffolds Although cryo-SEM reduces the amount of ice-induced damage generated in ‘soft’ scaffolds upon freezing, the technique is limited to the same constraints Images produced via scanning confocal microscopy are probably more representative of the true structure of the scaffold than that implied by cryo-SEM, although due to the diffuse nature of the image it is difficult to measure pore sizes

Book ChapterDOI
TL;DR: In this paper, hydrogen and helium measurements in pure nickel irradiated to 100 dpa in HFIR at temperatures between 300 and 600C show higher gas concentrations than predicted from fast-neutron reactions and the two-step 58Ni(n,g)59Ni (n,p and n,a) reactions, suggesting previously unidentified nuclear sources of helium and possibly hydrogen that assert themselves at very high neutron exposure.
Abstract: Hydrogen and helium measurements in pure nickel irradiated to 100 dpa in HFIR at temperatures between 300 and 600C show higher gas concentrations than predicted from fast-neutron reactions and the two-step 58Ni(n,g)59Ni(n,p and n,a) reactions. This additional gas production suggests previously unidentified nuclear sources of helium and possibly hydrogen that assert themselves at very high neutron exposure. The elevated hydrogen measurements are especially surprising since it is generally accepted that hydrogen is very mobile in nickel at elevated temperatures and therefore is easily lost, never reaching large concentrations. However, it appears that relatively large hydrogen concentrations can be reached and retained for many years after irradiation at reactor-relevant temperatures. These new effects may have a significant impact on the performance of nickel-bearing alloys at high neutron fluences in both fission and fusion reactor irradiations.

Journal ArticleDOI
TL;DR: A linear relationship was observed between the flowability measured by the flow cylinder method (ASTM D 6103) and the inverted slump cone method (INSCO) as mentioned in this paper for estimating sufficient bearing capacity.
Abstract: Flow consistency and setting time are two important properties of controlled low-strength materials (CLSM). This paper describes and evaluates several standard and non-standard methods to measure these properties. Several mixtures with a range of water-to-binder ratios were investigated through a series of field and laboratory experiments. A linear relationship was observed between the flowability measured by the flow cylinder method (ASTM D 6103) and the inverted slump cone method. Pocket penetrometer and Torvane measurements were compared to the Kelly Ball method (ASTM D 6024) for estimating sufficient bearing capacity. Pocket penetrometer resistance correlates well, but its capacity was often exceeded. Volume stability should be controlled to avoid softening of the surface and subsequent delays in measured hardening time.

Journal ArticleDOI
TL;DR: In this article, the stress and temperature dependence of creep at low swelling for selected 316 stainless steels and HT9 steels irradiated at temperatures from 400-670°C was investigated.
Abstract: A large amount of data on irradiation creep of face centered cubic (FCC) and body centered cubic (BCC) steels have been analyzed and published by the present authors, but a recent reanalysis of these data have provided further insight into irradiation creep behavior. The present paper looks at the stress and temperature dependence of creep at low swelling for selected 316 stainless steels and HT9 steels irradiated at temperatures from 400–670°C. Analysis of the creep data has revealed that a transition from a lower creep rate with a stress exponent of one to a higher creep rate with an unknown stress exponent occurs in FCC and BCC steels at moderate stresses, and the transition stress is approximately the same for both classes of steels. Due to limited data at higher stresses, the nature of the creep behavior at stresses greater than the transition stress cannot be unambiguously defined. One possibility is that the stress exponent is transitioning from a value of one to a value greater than one. Another possibility is that the creep compliance value is transitioning to a higher value while the stress exponent remains at a value of one. The creep compliance coefficients of the FCC and BCC steels have also been carefully reanalyzed in the regime where the stresses are lower than the transition stress, and in this regime there is a clear delineation in the creep compliance values between 316 stainless steels, titanium-modified 316 steels, and HT9 steels as a function of temperature.

Journal ArticleDOI
TL;DR: In this paper, the authors showed that oxidized ultra-high molecular weight polyethylene (UHMWPE) exhibits a different fatigue crack initiation and propagation behavior compared to unoxidized virgin, and crosslinked UHMW PE.
Abstract: We hypothesized that oxidation would influence the resistance to fatigue crack initiation and propagation of Ultra-High molecular weight polyethylene (UHMWPE). We subjected tibial insert surrogates (ram extruded GUR 1050) to accelerated aging protocols following ASTM F 2003-00 (14, 21 and 28 days). Subsurface disc specimens from the control and aged materials at each time period were subjected to cyclic small punch loading to failure (modification of ASTM F 2183-02). A significant decrease in fatigue loading was observed, relative to the un-aged controls, starting at three weeks of accelerated aging. Furthermore, SEM examination of the failed aged specimens revealed a network of multiple secondary initiation sites, which was also confirmed by observation with endoscopy, and microCT. Thus, in contrast to the unoxidized highly crosslinked conventional materials evaluated previously, the oxidized materials failed by the initiation and propagation of cracks from numerous initiation sites with the brittle appearance increasing with oxidation time. These results suggest that oxidized UHMWPE exhibits a different fatigue crack initiation and propagation behavior compared to unoxidized virgin, and crosslinked UHMWPE. Future studies will be needed to increase our understanding of the clinically acceptable fatigue properties for new tibial bearing materials, such as highly crosslinked UHMWPEs.

Journal ArticleDOI
TL;DR: In this paper, the potential of using two types of FGD materials (spray dryer and wet fixated FGD material) in flowable fill as a replacement for conventional fly ash Several design mixes were considered The design mixes consisted of varying amounts of FGDs material, cement, lime, and water The mixes were tested in the laboratory for flowability, unit weight, moisture content, unconfined compressive strength, erodibility, set-time, penetration, and long-term strength characteristics Tests were conducted for up to 90 d of curing without any additives, the FG
Abstract: Flowable fills are an effective and practical alternative to commonly used compacted earth backfills Flowable fill is a cementious material, commonly a blend of cement, fly ash, sand, and water, that does not require compaction, may be self-leveling at time of placement, may harden quickly within a few hours, and can be excavated in the future if need be Many flue gas desulfurization (FGD) materials have low unit weight and good shear strength characteristics and thus hold promise for flowable fill applications This paper focuses on the potential of using two types of FGD materials (spray dryer and wet fixated FGD material) in flowable fill as a replacement for conventional fly ash Several design mixes were considered The design mixes consisted of varying amounts of FGD material, cement, lime, and water The mixes were tested in the laboratory for flowability, unit weight, moisture content, unconfined compressive strength, erodibility, set-time, penetration, and long-term strength characteristics Tests were conducted for up to 90 d of curing Without any additives, the FGD material was observed to be as good as a regular (normal set) flowable fill in terms of placeability, unconfined compressive strength, and diggability FGD material flowable fill with additives and admixtures compares favorably with the characteristics of conventional quick set flowable fills

Journal ArticleDOI
TL;DR: In this paper, a tentative hydrogen absorption mechanism is proposed, explaining both roles of the electrochemical potential gradient over oxide film and the SPP window for the hydrogen absorption, and Zr2(Fe,Ni)-type precipitate might be oxidized easily in the oxide film, thus it might not contribute to the window for hydrogen absorption.
Abstract: The latest PIE results of Zry-2 and HiFi alloy (0.4 %Fe-Zry2) showed that iron addition reduces the hydrogen pick-up ratio. In order to clarify this lower hydrogen absorption mechanism, three types of experiments were carried out for both alloys: (1) Measurements of the hydrogen pick-up ratio in the pre-transition region using an autoclave. (2) CPD ( C ontact P otential D ifference) and FBP ( F lat- b and P otential) measurements of oxide film using a High Temperature Kelvin system and Photocurrent system. (3) Investigation of hydrogen absorption properties by Sieverts system and corrosion properties by autoclave for intermetallic compounds simulating SPP's Fe/Cr and Fe/Ni ratio in Zry-2 and HiFi. Autoclave tests showed that the corrosion behaviors of both alloys were similar. However, the hydrogen pick-up ratio depended on not only iron addition but also surface treatment (with and without pickling). Iron addition and non-pickling (as-received) reduced the hydrogen pick-up ratio. ΔCPD and FBP shifted to the positive side as the result of iron addition, and FBP changed with and without pickling. This difference in surface potential might be caused by the existence of anion vacancy concentration in the oxide film and furthermore may affect the electrochemical potential gradient over the oxide film. This potential gradient might control the proton diffusion in the oxide film. In the results of the hydrogen absorption tests on intermetallic compounds, Zr(Fe,Cr)2 with a higher Fe/Cr ratio showed lower hydrogen absorption, and Zr2(Fe,Ni) showed higher hydrogen absorption than Zr(Fe,Cr)2. In the results of corrosion tests on intermetallic compounds, Zr2(Fe,Ni) showed a much larger corrosion rate than Zr(Fe,Cr)2. It is considered that Zr2(Fe,Ni)-type precipitate might be oxidized easily in the oxide film, thus it might not contribute to the window for hydrogen absorption, and Zr(Fe,Cr)2 with a higher Fe/Cr ratio would reduce the amount of hydrogen penetrating through SPP at the oxide/metal interface. Based on these results, a tentative hydrogen absorption mechanism is proposed, explaining both roles of the electrochemical potential gradient over oxide film and the SPP window for the hydrogen absorption.

Book ChapterDOI
TL;DR: In this article, the authors examine the components of intimidation in ice hockey and to determine their effects on players, coaches, and referees, and develop a preliminary intimidation model based on sociological factors.
Abstract: The purpose of this investigation was to examine the components of intimidation in ice hockey and to determine their effects on players, coaches, and referees. In a pilot test, hockey coaches (N = 17) from three levels of participation were invited to an informal, exploratory symposium to assess their opinions on the role of intimidation in ice hockey. The following themes emerged: a) coaches' behavior and expectations, b) observable behavior, c) player's perceived role, and d) sociological factors. A preliminary intimidation model was developed. A survey including 80 open-ended questionnaires designed to stimulate discussion on the definition of intimidation, methods used to intimidate, and factors perceived as intimidating, was distributed to players (N = 66), coaches (N = 8), and referees (N = 6). The data were analyzed using qualitative methods [1,2] and intimidation was defined. Results support a theoretical model, which serves as a point of departure for future research and visually depicts the components of intimidation and their interactions.

Journal ArticleDOI
Yasumitsu Tomita1, Kiyoshi Hashimoto1, Naoki Osawa1, K. Terai1, Y.H. Wang1 
TL;DR: In this paper, the load sequence effect on fatigue life variability is examined by the use of a fatigue design procedure proposed by the authors, and the worst possible loading sequence is elucidated for the fatigue life of the ship's hull.
Abstract: Although ship structural members are designed to survive 20 years, fatigue crack damage still occurs, often starting very early in the ship's life, with some cracks growing quickly to considerable size. The primary factor causing variability is the sequence of the variable amplitude load cycle, and the others are welding irregularities on the weld toe and variations in mechanical properties in the material. In this paper, the load sequence effect on fatigue life variability is examined by the use of a fatigue design procedure proposed by the authors. It is found that the fatigue lives of ship structural members vary from several months to 20 years, strongly dependent on the sequence of sea state which ships encounter during ocean-going service. The worst possible loading sequence is elucidated for the fatigue life of the ship's hull. Sensitivity study of fatigue life is discussed.

Journal ArticleDOI
TL;DR: The results indicate that the cell isolation method affects the attachment, proliferation, and type of tissue formed by cells cultured under identical conditions.
Abstract: Cells are used in bone tissue engineering applications to facilitate new bone formation in implants. Enzymatic digestion and marrow removal by either centrifugal force or syringe are three methods used to isolate the cells for culture, but each technique has benefits and drawbacks. This comparative study evaluated the effects of the three cell isolation techniques on the attachment, proliferation, and mineralization of rat bone cells. Cells were isolated, seeded, and cultured following standard protocols for each isolation method. Quantitative assays to determine metabolic activity, lactic acid production, glucose consumption, and amounts of intracellular protein, alkaline phosphatase activity, and extracellular calcium were performed. In addition, cell morphology and viability were examined qualitatively. The results indicate that the cell isolation method affects the attachment, proliferation, and type of tissue formed by cells cultured under identical conditions.

Journal ArticleDOI
TL;DR: In this paper, a probabilistic method was used to predict the variability of fatigue life in quenched and tempered AISI 4340 steel in two stress levels by growing inclusion size fracture mechanics flaws using an existing linear elastic fracture mechanics crack growth model.
Abstract: Fatigue cracks in metals have been observed to form at nonmetallic inclusions in the matrix of the material, with the size of such features influencing fatigue life. A probabilistic method was used to predict the variability of fatigue life in quenched and tempered AISI 4340 steel. Crack growth analyses, presented as cumulative distribution functions of probability of failure, were made at two stress levels by growing inclusion size fracture mechanics flaws using an existing linear elastic fracture mechanics crack growth model. Initial flaw sizes were obtained from two separate distributions: one representing the overall inclusion population, and the other a subdistribution representing crack forming inclusions. In general, analyses correlated well with experimental lives, typically being within 25 %. The two initial flaw size distributions produced similar results; however, predictions based on the total inclusion distribution were heavily dependent on the threshold value. With the appropriate value of crack growth threshold, good correlation with variability can be made without requiring fatigue testing, particularly for the more critical shorter lives.

Journal ArticleDOI
TL;DR: In this article, the authors present an analysis of fatigue crack growth on M(T) specimens of medium carbon steel specimens and using FEM analyses, they conclude that the interaction effects are closely related to the cyclic plastic behavior of the material and namely to the Bauschinger effect.
Abstract: Under constant amplitude loading a single variable (ΔK) is required in crack growth relationships. The transferability of fatigue laws, determined under constant amplitude loading, to variable amplitude fatigue requires at least an additional variable, whose evolution with crack length accounts for the interaction effects between cycles of different types. The crack opening level (Kop) is usually employed for this purpose because it can be determined from the experiments and compared with predictions from models or FEM analyses. This paper presents an analysis of fatigue crack growth on M(T) specimens of medium carbon steel specimens and using FEM analyses. The specimens are subjected to repeated blocks of cycles made up of one or several overloads separated by a variable number of baseline cycles. The experiments are simulated by FEM analyses, taking into account the cyclic plastic behavior of the low carbon steel. The main objective of this study is to better understand the mechanisms at the origin of interactions effects due to the presence of overloads (or underloads) at different locations of the block loading. It is concluded that the interaction effects are closely related to the cyclic plastic behavior of the material and namely to the Bauschinger effect.

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TL;DR: In this paper, controlled low-strength materials (CLSM) were made in the field using one source of wood fly ash as a major component, and the CLSM mixtures S-1, S-2, and S-3 showed respective compressive strength values of 0.8, 0.3, and 0.6 MPa.
Abstract: Controlled low-strength materials (CLSM) were made in the field using one source of wood fly ash as a major component. CLSM Mixtures S-1 and S-3 contained cement, wood fly ash (81 and 89%, respectively, by mass of cementitious materials (Cm)), and sand; whereas, Mixture S-2 contained cement, wood fly ash (11% of Cm), Class C coal fly ash (67% of Cm), and sand. Mixtures S-1, S-2, and S-3 showed respective compressive strength values of 0.8, 0.3, and 0.6 MPa at 28 d, and 1.4, 14.4, and 1.0 MPa at one year. Combination of wood and coal fly ashes might have caused the drastic increase in the strength of Mixture S-2 at late ages. The respective water permeability values of Mixtures S-2 and S-3 decreased from 68 and 33 µm/s at 63 d to 6 and 12 µm/s at 227 d due to the improvement of microstructure of these CLSM mixtures.

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TL;DR: In this paper, the shape of the fracture-toughness master curve for a high-embrothment RRPV was investigated in terms of static initiation (KIc, KJc) and Charpy impact toughness in unirradiated and irradiated conditions.
Abstract: The Heavy-Section Steel Irradiation Program at Oak Ridge National Laboratory (ORNL) includes a task to investigate the shape of the fracture toughness master curve for reactor pressure vessel steel highly embrittled as a consequence of irradiation exposure. A radiation-sensitive reactor pressure vessel (RPV) weld with intentionally enhanced copper content, designed KS-01, is characterized in terms of static initiation (KIc, KJc) and Charpy impact toughness in the unirradiated and irradiated conditions. The objective of this project is to investigate the ability of highly embrittled material to maintain the shape of the unirradiated transition fracture toughness curve, as well as to examine the ability of the Charpy 41-J shift to predict the fracture toughness shift at such a high level of embrittlement. Irradiation of this weld was performed at the University of Michigan Ford Reactor. Specimens of KS-01 weld were irradiated to about 0.74 × 1019 neutron/cm2 at 288°C. Irradiation resulted in Charpy ductile-to-brittle transition temperature (DBTT) shift of 169°C. It was anticipated that this shift would result in a fracture toughness transition temperature (at 100 MPa√m) in the irradiated condition near or slightly above the pressurized thermal shock screening criterion for weld metals, ToPTS = 129°C. The fracture toughness characterization of KS-01 weld in the unirradiated and irradiated conditions was mainly performed by testing 1T C(T), although some 0.5T C(T) and precracked Charpy specimens were used in this study. The master curve analysis showed that this material exhibited shift of reference fracture toughness transition temperature, To, of 165°C as result of radiation, which is in remarkable agreement with Charpy DBTT shift. The absolute value of To in the irradiated condition was determined to be equal to 139°C. This weld exhibited a low ductile initiation toughness (JQ) after irradiation. It left a relatively narrow temperature window to examine the shape of the transition region. Irradiated median fracture toughness values up to 148 MPa√m follow the master curve shape. However, low toughness brittle fractures occurred at temperatures further above To (To + 61°C) than expected with a leveling of the KJc data from the master curve shape. The microstructure of the weld was characterized with the ORNL's energy-compensated optical position-sensitive atom probe. Atom probe tomography revealed a high number density (∼3 × 1024 m−3) of Cu-, Mn-, Ni-, Si-, and P-enriched precipitates and a lower number density (∼1 × 1023 m−3) of P clusters.

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TL;DR: In this paper, an alternative approach is presented that links fatigue crack growth parameters to material and microstructural size parameters via a microstructure-based fatigue crackgrowth (FCG) model, where the influence of changes in the main descriptors of the individual micro-structural parameters on initial crack size, crack growth rate, and fatigue life is shown.
Abstract: Most of the existing crack growth models rely on empirical constants derived from curve fits of data at specific test conditions. Although statistical information can be obtained for many of these constants, multiple experimental tests typically must be performed to represent the wide range of the response. In this paper, an alternative approach is presented that links fatigue crack growth parameters to material and microstructural size parameters via a microstructure-based fatigue crack growth (FCG) model. In addition, variation of initial crack size due to microstructural variation is modeled in terms of a crack-size-based fatigue crack initiation model. Variations of microstructural parameters are described in terms of a probabilistic framework. The probabilistic, microstructure-based, FCG approach is illustrated for a Ni-based superalloy in which the influence of changes in the main descriptors of the individual microstructural parameters on initial crack size, crack growth rate, and fatigue life is shown. Stochastic model results are compared with existing experimental data to illustrate the feasibility of the approach for predicting da/dN variability due to microstructure variations.