Showing papers on "Photoelasticity published in 1985"
TL;DR: In this paper, a new method of photoelastic measurement has been developed, where the light emerging from a polariscope is spectrally separated and projected on a photodiode array.
Abstract: A new method of photoelastic measurement has been developed. The light emerging from a polariscope is spectrally separated and projected on a photodiode array. It is shown that the relative retardation can be retrieved from light intensity measured at several wavelengths. Key parameters affecting the precision of this approach are discussed and evaluated.
76 citations
TL;DR: In this article, the load distribution and normalized stress distribution in the threads of an ISO metric nut and bolt were found by frozen-stress photoelastic analysis employing a fringe-multiplying polariscope in conjunction with a recording microdensitometer.
Abstract: The load distribution and the normalized stress distribution in the threads of an ISO metric nut and bolt were found by frozen-stress photoelastic analysis employing a fringe-multiplying polariscope in conjunction with a recording microdensitometer. Previous investigators assumed that these distributions were identical, whereas the present study shows that this is not the case. It has been further shown that deducing the load distribution from measurements of the nut deformation is unsatisfactory. The results of the reported method correlate closely with Sopwith's theoretical load distribution. Three recent finite-element analyses of nut-bolt systems have been compared indirectly to the experimental load distribution. That of Bretl and Cook was found to give the best comparison.
65 citations
TL;DR: In this paper, the theoretical foundations of a system of new methods which the authors call "isodyne photoelasticity" are presented, and the results are used to assess the reliability of some analytical solutions.
Abstract: The theoretical foundations of a system of new methods which the authors call ‘isodyne photoelasticity’ are presented. It is shown that the plane-elastic isodynes related to two-dimensional stress fields can be obtained experimentally using particular scattered-light techniques. The experimentally obtained photoelastic isodynes allow non-destructive analysis of stresses in structures with local three-dimensional stress states. Isodyne photoelasticity is used to determine stresses in composite structures, in particular the stresses at internal discontinuities and the delaminating stresses. The results are used to assess the reliability of some analytical solutions. The theories of isodynes and of the developed experimental techniques of isodyne photoelasticity are presented in a manner compatible with contemporary concepts of the models of reality—physical models, mathematical models, and experimental models constructed of matter and energy.
26 citations
TL;DR: In this article, the stresses in transparent glass-epoxy plates loaded by a steel pin through a hole were determined experimentally using photoelasticity, and the stresses around the hole edge, across the net section, along the shear-out line, and on the centerline below the hole for quasi-isotropic, unidirectional, and angle-ply plates were shown.
Abstract: The stresses in transparent glass-epoxy plates loaded by a steel pin through a hole were determined experimentally using photoelasticity. The paper presents the stresses around the hole edge, across the net section, along the shear-out line, and on the centerline below the hole for quasi-isotropic, unidirectional, and angle-ply plates. Stresses in an isotropic comparison specimen are also presented. Stress concentration factors for several locations around the plates are tabulated. The paper discusses the experimental approach and the isochromatic and isoclinic fringe patterns for the four plates are shown.
26 citations
TL;DR: Stress intensity factors along the front of semicircular and part-circular surface flaws in bodies under uniform tension and under pure bending have been determined by photoelastic stress freezing and compared to other solutions as discussed by the authors.
Abstract: Stress intensity factors along the front of semicircular and part-circular surface flaws in bodies under uniform tension and under pure bending have been determined by photoelastic stress freezing and compared to other solutions The variation of K1 reflects the change in the stress singularity λ, from 05 at the deepest point to 03 at the surface The importance of the results on the evaluation of crack growth using traditional linear elastic fracture mechanics is discussed
22 citations
TL;DR: Three-dimensional stress distribution in a model of the human ankle joint under static loading has been measured nondestructively in real time by using the scattered-light polarizer photoelastic method with depolarized incident light.
Abstract: Three-dimensional stress distribution in a model of the human ankle joint under static loading has been measured nondestructively in real time by using the scattered-light polarizer photoelastic method with depolarized incident light. The maximum shear stress distribution in the interior of the model is obtained by optical slicing with the incident light sheets. The stress pattern in the interior of the model can be examined visually as contour lines of the maximum shear stress distribution as well as in 2-D plane-light photoelasticity.
11 citations
TL;DR: In this article, the authors dealt with an experimental characterization of cracked lugs, using frozen-stress photoelasticity, and various effects on SIF were assessed, including corner, transitioning and through-the-thickness cracks.
10 citations
TL;DR: In this article, the residual stresses in a model of a plastically encapsulated microelectronic device are determined photoelastically using birefringent transfer-molding compounds.
Abstract: The residual stresses in a model of a plastically encapsulated microelectronic device are determined photoelastically using birefringent transfer-molding compounds. The measured stresses are compared with a laminated-platetheory analysis and then used to guide a two-dimensional finite-element analysis of the device. Photoelasticity was also used to determine the effects of postcure on the residualstress distribution.
10 citations
TL;DR: In this article, the elastodynamic interaction between explosively generated body and surface wave and an edge crack in a quarter-plane was investigated, and the authors employed dynamic photoelasticity to obtain full-field information for data analysis.
Abstract: The elastodynamic interaction between explosively generated body and surface wave and an edge crack in a quarter-plane is investigated. Dynamic photoelasticity was employed to obtain full-field information for data analysis. Measurements of the stress distribution along the free boundaries of the quarter-plane and along the crack walls have been made. Stress intensity distributions at both, the corner and the flaw tip and surface stress distributions for the diffracted and reflected Rayleigh-waves were obtained in the region near the cracked corner.
9 citations
TL;DR: There is an array of full field experimental stress analysis techniques available to aid the designer or the engineer investigating service failures as discussed by the authors, including photoelasticity, moire, laser holography, brittle lacquer and SPATE.
Abstract: There is an array of full field experimental stress analysis techniques available to aid the designer or the engineer investigating service failures. This note reviews currently available methods (i.e. photoelasticity, moire, laser holography, brittle lacquer and SPATE) and assesses their relative merits in practical applications.
TL;DR: In this article, the principal stress distribution in a semi-infinite plate with a rectangular hole during the propagation of a stress wave was solved using a polyester model having a partially reflecting front surface and a double-pulse Ruby laser, each pulse having an energy of 0·5 J.
TL;DR: In this article, the authors used the mixed-mode, elastodynamic state of stress in the neighborhood of a constant-velocity crack tip to generate numerically unsymmetric isochromatics.
Abstract: The mixed-mode, elastodynamic state of stress in the neighborhood of a constant-velocity crack tip is used to generate numerically unsymmetric isochromatics. Unsymmetry associated with the third-order terms of a mixed-mode stress field, with and without the Mode II singular stress term, is also investigated. In extractingK
I
from an unsymmetric isochromatic pattern, errors in the Mode I fracture parameters due to the assumed presence ofK
II
in aK
I
stress field were found to be significant when data are taken more than 4 mm from the crack tip.
TL;DR: In this article, the use of an automatic recording microdensitometer in conjunction with a fringe multiplying polariscope for analysing small portions of slices from frozen stress photoelastic models is described in detail.
Abstract: The use of an automatic recording microdensitometer in conjunction with a fringe multiplying polariscope for analysing small portions of slices from frozen stress photoelastic models is described in detail. The method is used to find the load distribution in the threads of a 30 mm ISO nut and bolt model. The accuracy is discussed and shown to be comparable to that of conventional photoelastic techniques.
TL;DR: Using the three‐dimensional photoelastic method a quantitative analysis was carried out on the tension trends in the proximal third of a normal human femur in a stationary weight‐bearing situation on two legs.
Abstract: Using the three-dimensional photoelastic method a quantitative analysis was carried out on the tension trends in the proximal third of a normal human femur in a stationary weight-bearing situation on two legs. The results obtained show that in this loading situation the maximum stress values (both for tension and compression) are in the area just below the subtrochanteric zone; while going up along the borders of the diaphysis, the tension trends do not vary appreciably. Moreover, the state of the stresses is not constant but varies slightly along the thickness of the bone. The neutral axis is considerably displaced towards the tensile area. A comparison between the stress tension trends in two different static loading situations (one-leg and two-leg support) was carried out. It was found that the maximum tensile stress value in the one-leg position was about 24 times greater than that in the two-leg position and the maximum compression stress value was about 14 times greater than in the two-leg situation.
Book•
01 Jan 1985
TL;DR: In this paper, the authors used a laser-dual-focus velocimetry and flow visualization of 3-D flows to evaluate dynamic photoelasticity of high loading rates.
Abstract: Optical methods in fluid and solid dynamics research.- Space resolved probing of gas concentration and temperature structures.- Holographic interferometry studies of the temperature field near a condensing bubble.- Laser raman techniques for gas phase fluid dynamics and combustion research.- Applied holography for drop formation of non-newtonian fluids in centrifugal atomizers.- Holographic mode shape investigation of aircraft engine impellers.- A study of heat transfer from a horizontal vibrating cylinder by means of holographic interferometry.- Study of diffraction of shock waves, at rounded corners by means of schlieren and interferometric methods.- Study of shock wave reflection in rectangular channels by means of Cranz-Schardin system in parallel beams.- Experience with laboratory LDA by measuring flow fields in rotating turbomachinery.- Application of laser-dual-focus velocimetry in a counterflow.- Laser-doppler velocimetry and flow visualization of 3-D flows.- Laser diagnostics of molecular states in non-equilibrium gas flows.- Experimental study of a turbulent boundary layer-shock wave interaction, using a monodimensional laser velocimeter.- Solution of diffuser inlet velocity field of radial impeller centrifugal turbine pumps by means of the LDA method.- Measurement of unstationary size-distribution of submicron droplets in rarefaction-wave condensation by laser scattering.- Investigation of initial stage of cavitation by diffraction optic method.- Optic and x-ray investigation of water fracture in rarefaction wave at later stages.- Experimental studies of stress waves in elastic plates with curved boundary.- Laser-doppler velocimetry applied to the impact testing of polymers.- Speckle photography of a turbulent density field.- Experimentally and theoretically generated isochromatic fringe loops of cracks propagating at a constant velocity.- Stresses and deformation pattern investigated by the Moire optical method in gears.- Photoelasticity studies of a new method of fracture toughness evaluation of high loading rates.- A new approach to evaluation of measurement in dynamic photoelasticity.- Optimization of a stiffener to stop a propagating crack.- Holographic interferometric study on propagation and focusing of underwater shock waves by microexplosions.- Flow visualization in the wake of three-dimensional bodies undergoing self-sustained oscillations.- Flow visualization of a shock wave by simple refraction of a background grid.- Flow visualization in steel casting.- Behaviour of the vortex layer generated in the flow by an impulse change of circulation around a profile.- Flow visualization of turbulent boundary layer on flat and cylindrical heated walls.- Investigation of transient phenomena in heat transfer.- Flow visualization in a steam turbine profile cascade using a colour schlieren method.- Colour schlieren method.- Photoelastic analysis of a seismoactive crack.- Study of flow of metal and stress conditions at rolling by means of optical methods.- Using interferometric measurements in caicuiation of aerodynamic forces.- Holographic interferometer to investigate deformations of mechanical and thermal stressed motorcar-cylinders.- A new application of differential interferometry for dynamic stress analysis.- Laser beam monitoring of shock waves.- Tomography of transient events.- Application of new photo-electric method to the measurement of dynamic stress intensity factor.- Experimental study of optical features of shock-heated jets.- An investigation of impulse jet outflowing from multi-nozzle blocks by means of the schlieren installation.- Karman vortex street in the supersonic wake a rough flat plate.- Migration of droplets under reduced gravity.- The methods for diagnosing velocity and temperature in the high-temperature gas flow.
Patent•
19 Apr 1985
TL;DR: In this paper, the authors proposed a transparence conductive film on the synthetic polymer substrate having ≤15 Brewster absolute value of a photoelasticity constant in a temp. less than a glass transition temp.
Abstract: PURPOSE: To obtain the titled substrate having a small optical strain and a high transparency by forming a transparence conductive film on the synthetic polymer substrate having ≤15 Brewster absolute value of a photoelasticity constant in a temp. less than a glass transition temp. of the synthetic resin. CONSTITUTION: The reason why the synthetic resin having ≤15 Brewster absolute value of the photoelasticity constant is used to the substrate, lies in generating various stress-strains in a molding of the substrate whereby a distribution of the optical birefringence index generates, when said value is more than 15. When the optical birefringence index is large, a slipping of a transmission light generates in the thick substrate, and the tremble of the visible image becomes a problem. The surface resistance value of the substrate is necessary to satisfy 10 -1 Ω/mm 2 W10 9 Ω/mm 2 . So that, as said conditions are fully satisfied, the conductive layer provided on the synthetic resin substrate is most preferable to be an acrylic resin plate. When the acrylic resin plate is used as the substrate, the surface of the substrate is performed a curing treatment, and then is vacuum-deposited a thin film of an oxide semiconductor on the surface of the substrate at a temp. of less than 100°C, thereby obtaining a transparent conductive film 2. COPYRIGHT: (C)1986,JPO&Japio
01 Jan 1985
TL;DR: In this paper, the critical analysis of Hopkinson Split Pressure Bar (HSPB) technique modified for dynamic fracture toughness KId measurement is performed by photoelasticity investigation of the model made from briefriegent material.
Abstract: The critical analysis of Hopkinson Split Pressure Bar (HSPB) technique modified for dynamic fracture toughness KId measurement is presented. The analysis is performed by photoelasticity investigation of the model made from briefriegent material. The obtained results together with numerical analysis enable to design of criteria which make possible to use the quasistatic approach to KId evaluation
TL;DR: In this article, the inner and outer boundaries of circular rings under internal diametral tension using two dimensional photoelasticity were optimized to reduce the stress concentration factor and weight.
Abstract: Optimisation of inner and outer boundaries of circular rings under internal diametral tension using two dimensional photoelasticity is presented. It is shown that, when shape optimisation of only one of the two boundaries in the field is carried out, there is an increase in the stresses on the other boundary. However, optimisation of both the boundaries is found to be beneficial with significant reduction in stress concentration factor and weight.
01 Jan 1985
TL;DR: In this paper, photoelastic and caustic experiments were conducted to obtain stress intensity factor, K, for both stationary and moving cracks, and the results showed that the accuracy varies with the location of the crack tip for both the methods.
Abstract: Photoelastic and caustic experiments are conducted to obtain stress intensity factor, K, for both stationary and moving cracks. For the stationary crack the values of K are compared with the available theoretical and numerical solutions. Results show that the accuracy varies with the location of the crack tip for both the methods. Six parameter analysis of the photoelastic data gives better values as compared to the caustic results which in turn are better than the values obtained by three parameter photoelastic analysis. Dynamic photoelastic experiments are conducted with SEN, DCB and DCB/SEN specimens. The data obtained from these experiments namely the stress intensity factor and crack velocity, is compared with existing results and also with the values obtained from dynamic caustic experiment with SEN specimen. significantly lower. of crack velocity Values from caustic analysis are Stress intensity factor as a function is plotted and the results show a dependence on specimen geometry for cracks moving at high velocities.
TL;DR: In this article, the effects of fiber-end geometries on the propagating stress waves in composite models were investigated by the dynamic photoelastic method by casting aluminum fibers with rectangular, semicircular, v- and wedgeshape ends simulating such materials as reinforced concrete and fiber-bundle-reinforced composites.
Abstract: The stress-concentration effect of fiber-end geometries on the propagating stress waves in composite models was investigated by the dynamic photoelastic method. Aluminum fibers with rectangular, semicircular, v- and wedgeshape ends simulating such materials as reinforced concrete and fiber-bundle-reinforced composites were cast in epoxy resin to form the models. Impact was applied by the bullet of a rilfe. The effects of the reinforced rod or fiber-bundle ends on the dynamic birefringent patterns were analyzed by comparing the fringe patterns at the same locations in a plain model of identical contour under the same loading conditions.
TL;DR: In this article, the three-dimensional axisymmetric boundary value problem of pressure vessels with torispherical drumheads is analyzed easily and accurately by the use of the indirect fictitious boundary integral method.
Abstract: The three-dimensional axisymmetric boundary value problem of pressure vessels with torispherical drumheads is analysed easily and accurately by the use of the ‘indirect fictitious-boundary integral method’. The analysed configurations are similar to each other but have different thicknesses. The comparison of the resent results with photoelasticity and shell theory solutions makes it clear that the shell theory based on Love's first approximation is very reasonable. Additionally, a vessel with hemispherical drumheads with varying thickness from cylinder to head, which is noteworthy for reducing the maximum stresses in the vessel, is studied.
TL;DR: In this paper, photoelasticity is one of the oldest methods (19th century) of Experimental Stress Analysis and it has been used from the beginning of its practical applications in the field of orthopaedics.
TL;DR: In this article, the singular stress distributions near crack-tips were analyzed for stress intensity factors (SIFs) under live-load and stress-frozen conditions using scattered-light photoelasticity.
01 Mar 1985
TL;DR: In this article, the results show that stress concentration in the elastoplastic state is lower than that in the elastic state and decreases continuously as yielding progresses, and a good agreement exists between results from both methods.
Abstract: : Photoplasticity and photoelastic coating techniques have been successfully employed to study stress concentration in the elastoplastic state and residual stress after unloading. Principles are described herein, and examples of the application of both methods are given. The results show that stress concentration in the elastoplastic state is lower than that in the elastic state and decreases continuously as yielding progresses. A good agreement exists between results from both methods.
01 Jan 1985
TL;DR: In this article, an application of dynamic photoelasticity to crack-arrestor effects on a brittle fracture propagation in order to extend the life of a precracked plate is presented.
Abstract: The purpose of this paper is to demonstrate an application of dynamic photoelasticity to crack-arrestor effects on a brittle fracture propagation in order to extend the life of a precracked plate.
15 Apr 1985
TL;DR: In this paper, an experimental method which integrates the methods of frozeg stress photoelasticity and high density moire interferometry together with appropriate algorithms for estimating three dimensional distributions of fracture parameters is presented.
Abstract: After briefly reviewing an experimental method which integrates the methods of frozeg stress photoelasticity and high density moire interferometry together with appropriate algorithms for estimating three dimensional distributions of fracture parameters, this paper f ocuses upon results obtained by the method pertaining to boundary effects and their possible interpretation within the mechanics
TL;DR: In this article, half fringe photoelasticity (HFP) was used to automate the data collection, analysis and display of full-field normal stresses in adhesively bonded single lap joint models under uniaxial tension.