Showing papers by "Lehigh University published in 1972"
TL;DR: In this article, a theory of non-local elasticity is presented via the vehicles of global balance laws and the second law of thermodynamics via the use of a localized Clausius-Duhem inequality and a variational statement of Gibbsian global thermodynamics.
2,201 citations
Book•
01 Jan 1972TL;DR: The Origin of Species is a rigorously documented but highly readable account of the scientific theory that now lies at the root of the authors' present attitude to the universe.
Abstract: With his revolutionary work "The Origin of Species", Charles Darwin overthrew contemporary beliefs about Divine Providence and the beginnings of life on earth. Written for the general public of the 1850s, it is a rigorously documented but highly readable account of the scientific theory that now lies at the root of our present attitude to the universe. Challenging notions such as the fixity of species with the idea of natural selection, and setting forth the results of pioneering work on the ecology of animals and plants, it made a lasting contribution to philosophical and scientific thought.
1,212 citations
TL;DR: In this article, a semi-infinite crack under concentrated wedge loading is considered and a tentative fracture criterion dealing with the initiation of fracture propagation is proposed, where the Mellin transform in conjunction with dislocations is used to formulate the problem and derive the integral equation.
525 citations
TL;DR: In this article, the authors measured measured capacitance and conductance curves of MOS structures with different metal contacts on 20−40 cm−2 V−1 SiO2 films and non-degenerate Si have been investigated.
Abstract: MOS structures having different metal contacts on 20–40 A thick SiO2 films and non-degenerate Si have been investigated. These structures show large frequency dispersion of the measured admittance curves caused by carrier recombination in interface states. However, build-up of a Si inversion layer is not observed because the minority carriers are drained away by tunneling through the oxide into the metal. Interface state density distributions across the whole Si band gap are obtained by evaluating measured capacitance and conductance curves. Characteristic peaks of 0.12–0.30 eV half width are found for the metal contacts, Mg at 0.54 eV, Cu at 0.23 eV, Cr at 0.18 eV and 0.52 eV, and Au at 0.15 eV and 0.97 eV above the valence band edge. The position of a peak seems to be related to the valence of the metal. Interface states caused by Cr, Cu and Mg contacts are of acceptor type. Their capture cross-section obtained from conductance measurements varies between 10−7 and 10−18 cm−2. A rapid increase of the state density with decreasing oxide thickness or sample annealing indicates that the states are caused by metal diffusion through the oxide into the interface. An observed saturation of the state density at about 2 × 1013 cm−2 V−1 is possibly due to a limited solubility of metal impurities in the oxide.
216 citations
TL;DR: In this article, the correction factors for the drop weight, or drop volume, technique for the determination of surface and interfacial tensions by Harkins and Brown have been expanded from the range 0.72080 ≥ψ(r/V13) ≥ 0.5352 to include the range of 0.9439 ≥ ψ( r/V 13) ≥0.720 80.
149 citations
TL;DR: It is shown that if g(x) GF(q)[x] is the generator polynomial of a cyclic code Vn of length n such that g(βl+i1c1+i2c2 = 0 for i1 = 0, 1,…, d0 — 2 and i2 = 1, then the minimum distance of Vn is at least d0 + s.
Abstract: Cyclic codes generated by polynomials having multiple sets of do — 1 roots in consecutive powers of a nonzero field element are considered and some generalizations of the BCH bound are presented In particular, it is shown, among other results, that if g(x) GF(q)[x[ is the generator polynomial of a cyclic code Vn of length n such that g(βl+i1c1+i2c2 = 0 for i1 = 0, 1,…, d0 — 2 and i2 = 0,1,…,s, where β GF(qm) is a nonzero element of order n and c1 , c2 are relatively prime to n, then the minimum distance of Vn is at least d0 + s
145 citations
01 Sep 1972
TL;DR: The changes in matrix structure that occur during tempering of an Fe-0.2C martensite at 400° to 700°C have been investigated in this article, showing that the fine martensitic lath structure coarsens while retaining the elongated packet-lath morphology.
Abstract: The changes in matrix structure that occur during tempering of an Fe-0.2C martensite at 400° to 700°C have been investigated. Light and electron metallographic observations show that when tempered, the fine martensitic lath structure coarsens while retaining the elongated packet-lath morphology. The as-quenched hardness 504 Khn and total grain boundary area per unit volume 50,800 cm−1 decrease abruptly at the higher tempering temperatures and in seconds reach relatively stable values that decrease slowly with time. The decrease in low angle boundaries accounts for most of the initial grain boundary area change, while the large angle boundary component of total boundary area decreases gradually with tempering time. Recovery processes are responsible for the initial changes in matrix structure, and carbide boundary pinning suppresses recrystallization until grain growth dominates in the later stages of tempering.
143 citations
TL;DR: In this paper, the transient stress and displacement fields around a finite crack opened out by normal and shear tractions applied to its surface are obtained using integral transforms coupled with the technique of Cagniard.
131 citations
TL;DR: In this article, a series of fracture problems in composite materials are identified, their methods of solution are briefly discussed, and some sample results are presented, the main problem of interest is the determination of the stress state in the neighborhood of localized imperfections such as cracks and inclusions which may exist in the composite.
129 citations
TL;DR: In this paper, the authors show that all intermolecular interactions in solution and at interfaces can be reduced to two phenomena: London dispersion forces, and electron donor-acceptor (acid-base) interactions.
Abstract: Nearly all intermolecular interactions in solution and at interfaces can be reduced to two phenomena: London dispersion forces, and electron donor-acceptor (acid-base) interactions. Hydrogen bonds are included in acid-base interactions, and dipole phenomena are usually negligibly small. Earlier popular notions that all “polar” groups can interact with each other are shown untenable; donor-donor and acceptor-acceptor interactions are negligibly small compared to donor-acceptor interactions. Supporting data include surface and interfacial tensions, contact angles, and adsorption of polymers from organic solvents onto inorganic powders.
119 citations
TL;DR: In this paper, the fatigue behavior of polycrystalline alumina was investigated and cyclic fatigue effect characterized by a frequency and amplitude dependence was also observed; possible mechanisms of cyclic fatigues in brittle materials are discussed.
Abstract: The fatigue behavior of a polycrystalline alumina was investigated. Stress conditions consisted of a static tensile stress and a static tensile stress with superposed sinusoidal cyclic stress. The alumina exhibited the expected static fatigue behavior; a cyclic fatigue effect characterized by a frequency and amplitude dependence was also observed. Possible mechanisms of cyclic fatigue in brittle materials are discussed.
TL;DR: In this paper, the martensite to austenite (α′ → γ) transformation was studied as a function of heating rate in a series of Fe-Ni-C alloys with carbon contents of 0.004, 0.05 and 0.6 wt.
TL;DR: In this paper, the Kubelka-Munk hyperbolic equation for reflectance and transmittance of a turbid, isotropically scattering medium has been found formally identical with the solution for reflected and transmitted fluxes of Chandrasekhar's radiative-transfer equation for highly scattering media.
Abstract: The Kubelka–Munk hyperbolic equations for reflectance and transmittance of a turbid, isotropically scattering medium have been found formally identical with the solution for reflected and transmitted fluxes of Chandrasekhar’s radiative-transfer equation for isotropically highly scattering media. The absorption and scattering coefficients of the two theories have been related through numerical coefficients. The Kubelka–Munk absorption coefficient is nearly proportional to the true absorption coefficient in the range of reflectance values between 0.6 and 1 but deviations from proportionality up to a factor of 2 occur for lower reflectance values.
01 Jan 1972
TL;DR: A review of the current state-of-the-art in fracture mechanics, particularly in relation to the study of problems in environment-enhanced fatigue crack growth, can be found in this article.
Abstract: Review of the current state-of-the-art in fracture mechanics, particularly in relation to the study of problems in environment-enhanced fatigue crack growth. The usefulness of this approach in developing understanding of the mechanisms for environmental embrittlement and its engineering utility are discussed. After a brief review of the evolution of the fracture mechanics approach and the study of environmental effects on the fatigue behavior of materials, a study is made of the response of materials to fatigue and corrosion fatigue, the modeling of the mechanisms of the fatigue process is considered, and the application of knowledge of fatigue crack growth to the prediction of the high cycle life of unnotched specimens is illustrated.
TL;DR: In this article, a constitutive theory for thermodynamic fluxes in terms of variational derivatives of a convex functional was proposed, which assumes its absolute minimum at Xa = 0, and it is shown that 0 ⩽ P ⩾ Φ [W;2X]−Φ[W;X] for all Xa and for all additional parameters Wα, and hence we have identical satisfaction of the Second Law of Thermodynamics.
TL;DR: In this paper, the authors used the flash desorption technique to study adsorption of hydrogen on very clean, reproducible surfaces of polycrystalline iron and showed that the initial rates of adsorment of hydrogen are consistent with an activated complex that requires about 0.5 kcal mole−1 for its formation, and this energy remains nearly constant up to a surface coverage of 0.2 × 1015 H-atoms cm−2.
01 Apr 1972-Metallurgical and Materials Transactions B-process Metallurgy and Materials Processing Science
TL;DR: In this paper, the freezing process in AISI type M2 high speed tool steel (6 pct W, 5 pct Mo, 4 pct Cr, 2 pct V, 8 pct C) was studied by metallographic and thermal analysis techniques.
Abstract: The freezing process in AISI type M2 high speed tool steel (6 pct W, 5 pct Mo, 4 pct Cr, 2 pct V, 08 pct C) was studied by metallographic and thermal analysis techniques Unidirectional solidification of small laboratory melts in a modified crystal growing apparatus was employed to provide metallographic sections of known macroscopic growth direction Also cooling curves were obtained on 40 g specimens solidified in thimble crucibles X-ray microradiography, electron probe scanning techniques, and quantitative microanalysis of dendrites and interdendritic carbides were extensively used to supplement conventional metallography Carbon and vanadium contents of M2 were varied in order to observe the effect of an austenite and ferrite stabilizer on the thermal analysis curves and microstructure The nonequilibrium freezing process in M2 includes three major liquid-solid reactions: 1) Liquid → Ferrite, 1435°C; 2) Liquid + Ferrite → Austenite, 1330°C; 3) Liquid → Austenite + M6C + MC, 1240°C These reactions account for the as-cast structure of the commercial alloy The addition of carbon depresses the liquidus (1) and solidus temperatures (3) and narrows the gap between the liquidus (1) and peritectic transformation (2) This gap is eliminated at > 139 wt pct C, where the initial freezing reaction is the crystallization of austenite The accompanying microstructural change is the elimination of σ eutectoid dendrite cores The addition of vanadium promotes ferrite formation by strongly depressing the peritectic reaction and thus widening the gap between the liquidus and the peritectic
TL;DR: The total protein concentrations in the hemolymph of noninfected Biomphalaria glabrata and those parasitized by Schistosoma mansoni have been compared and it has been ascertained that both the total protein and hemoglobin concentrations in snails of different sizes vary; specimens measuring between 10 and 16 mm in diameter tend to include more hemoglobin than larger ones.
TL;DR: The characterization of the types of cells present in C. virginica hemolymph, it is now possible to study the constituents and roles of each in their reactions to foreign substances.
TL;DR: In this article, the growth of planar jets is studied using the hydrogen bubble technique of flow visualization and the generation of streaklines and timelines permit characterization of the process of vortex formation and coalescence.
Abstract: : The growth of planar jets is studied using the hydrogen bubble technique of flow visualization. Flows which are initially laminar and initially turbulent at the nozzle exit are considered. Generation of streaklines and timelines permit characterization of the process of vortex formation and coalescence. Both symmetrical and asymmetrical modes of vortex growth and coalescence, along with the resultant deformation of the jet core flow, are examined. Nascent and mature stage coalescence are defined and portrayed. Vortex axial transport velocity and frequency of formation of the vortices are evaluated for selected Reynolds numbers. (Author)
TL;DR: In this article, the authors considered the stress analysis of a metal base plate stiffened by a fiber-reinforced composite layer and reduced the problem to a pair of integral equations of the second kind with Fredholm-type kernels.
TL;DR: In this article, a wide range of polybutadiene (PB) and polystyrene (PS) compositions were synthesized and electron microscopy studies revealed an irregular cellular structure of a few hundred Angstrom diameter with the first component, PB, making up the cell walls.
Abstract: Interpenetrating polymer networks (IPN's) of polybutadiene (PB) and polystyrene (PS) were prepared using both random (containing 36% cis, 55% trans, and 9% 1,2 vinyl) PB and high-cis PB. For both series, a wide range of PB/PS compositions were synthesized. Using samples stained with osmium tetroxide, electron microscope studies revealed an irregular cellular structure of a few hundred Angstrom diameter with the first component, PB, making up the cell walls. The size of the cells was found to depend on the PB crosslink density for the random materials. Modulus-temperature data revealed two distinct glass transitions, confirming the microscopy finding of two phases. However, the transition temperature and transition slope varied with composition, and with the microstructure of the polybutadiene, giving evidence of significant molecular mixing. Stress-strain data on the IPN's showed that materials rich in PB behave like self-reinforced elastomers. Charpy impact resistance experiments on materials rich in PS indicated values of 5 ft-lb/in. of notch, which compares well with graft-type polyblends of similar PB/PS composition. The results were interpreted in the light of the recent theoretical work of Bragaw, who considered the importance of the distances between domain boundaries with respect to crack acceleration mechanics. Although the IPN's considered herein exhibited somewhat less than the predicted optimum phase dimensions, the arrangement of the domains is different from ordinary impact resistant plastics.
TL;DR: In this article, the steady-state, continuous couter current contacting of SO 2 -bearing air with water in a column packed with carbon was modeled by combining the classical treatment for gas absorption with expressions for the rate of transport through the liquid and for the catalytic oxidation within the porous carbon.
TL;DR: In this paper, the plane elastostatic problem for bonded materials containing a flat inclusion is considered and the stress intensity factors are presented as functions of the ratio of the distance from the interface to the length of the inclusion.
TL;DR: The distribution and abundance of surface zooplankton in the Sandy Hook Bay area were studied biweekly from May 1969 through May 1970, where planktonic harpacticoid copepods atypically comprised over 50% of the population.
Abstract: The distribution and abundance of surface zooplankton in the Sandy Hook Bay area were studied biweekly from May 1969 through May 1970 This embayment is located within the commercially valuable New York Bight The volumetric mean of the plankton ranged from 02-53 cc/m3, with a survey mean of 18 cc/m3 A maximum crop of 52,002 organisms/m3 was collected in May 1970 Calanoid copepods were the dominant forms recovered in this survey; however, in May, planktonic harpacticoid copepods atypically comprised over 50% of the population A general salinity classification of the copepods is presented
TL;DR: In this article, the axially symmetric elastostatic problem for a layer bonded to a half space with different material properties is considered and the solution of the problem is reduced to that of a system of singular integral equations of the second kind.
TL;DR: In this paper, the fracture criterion of critical COD was verified by using the results of the burst tests in titanium and aluminum alloy cryogenic pressure vessels, and the model was applied to the analysis of experimental data obtained from flat plates and cylindrical shells under axial tension, internal pressure, and torsion.