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A non-dimensional, axisymmetric, thermal-stress model for a three-layer cylinder with internal heating has been developed. Such a geometry is encountered in an annular target for isotope production. The middle cylinder is the heat generating source with an assumed thermal expansion coefficient that is smaller than that of the other two cylinders enclosing it. Hence, the development of the solution is based on the assumption that interfacial separation occurs at the interface of the middle cylinder and the outer cylinder, while contact is reinforced between the middle cylinder and the inner cylinder. The commercial finite element code Abaqus FEA is used to obtain a numerical model which is validated using the developed analytical solution. The non-dimensional analytical solution has been presented in a simplified, generalized form, and can be applied to either of the cylinders by adjusting a few parameters. The non-dimensional variable groupings allow physical insight into how the stresses and temperature distributions evolve. A detailed solution procedure along with a discussion of the results has been provided.

This study delves with the reflection phenomenon of plane-waves due to incidence of quasi-longitudinal (QL) wave at a semi-infinite structure comprising of pre-stressed piezoelectric-orthotropic su...

Residual stress is generally evaluated using indentation by comparing the indentation curves of stressed and stress-free states. Here, we suggest a new method that can evaluate surface residual stress without indentation testing on stress-free specimen using stress-independent indentation parameters and an analysis of indentation contact morphology for the stress-free state. We found that several indentation parameters are independent of the stress by Vickers indentation testing on various stress states. The indentation contact morphology can be represented by indentation parameters including stress-independent ones, and by applying the stress-independent parameters obtained from the stressed state to the indentation contact depth function, we can estimate an indentation curve for stress-free state. The estimated curve matches well with the experimental stress-free indentation curve, and it was also confirmed that the applied stress values evaluated by comparing the estimated curve with the stressed indentation curve agree well with the reference values obtained from strain gauge.

Steady two-dimensional Rayleigh--B\'enard convection between stress-free isothermal boundaries is studied via numerical computations. We explore properties of steady convective rolls with aspect ratios $\pi/5\le\Gamma\le4\pi$, where $\Gamma$ is the width-to-height ratio for a pair of counter-rotating rolls, over eight orders of magnitude in the Rayleigh number, $10^3\le Ra\le10^{11}$, and four orders of magnitude in the Prandtl number, $10^{-2}\le Pr\le10^2$. At large $Ra$ where steady rolls are dynamically unstable, the computed rolls display $Ra \rightarrow \infty$ asymptotic scaling. In this regime, the Nusselt number $Nu$ that measures heat transport scales as $Ra^{1/3}$ uniformly in $Pr$. The prefactor of this scaling depends on $\Gamma$ and is largest at $\Gamma \approx 1.9$. The Reynolds number $Re$ for large-$Ra$ rolls scales as $Pr^{-1} Ra^{2/3}$ with a prefactor that is largest at $\Gamma \approx 4.5$. All of these large-$Ra$ features agree quantitatively with the semi-analytical asymptotic solutions constructed by Chini \& Cox (2009). Convergence of $Nu$ and $Re$ to their asymptotic scalings occurs more slowly when $Pr$ is larger and when $\Gamma$ is smaller.

The multiplicative decomposition model is widely employed for predicting residual stresses and morphologies of biological tissues due to growth. However, it relies on the assumption that the tissue is initially in a stress-free state, which conflicts with the observations that any growth state of a biological tissue is under a significant level of residual stresses that helps to maintain its ideal mechanical conditions. Here, we propose a modified multiplicative decomposition model in which the initial state (or reference configuration) of a biological tissue is endowed with a residual stress instead of being stress-free.Releasing theoretically the initial residual stress, the initially stressed state is first transmitted into a virtual stress-free state, thus resulting in an initial elastic deformation. The initial virtual stress-free state subsequently grows to another counterpart with a growth deformation, and the latter is further integrated into its natural configuration of a real tissue with an excessive elastic deformation that ensures tissue compatibility. With this decomposition, the total deformation arising during growth may be expressed as the product of elastic deformation, growth deformation and initial elastic deformation, while the corresponding free energy density should depend on the initial residual stress and the total deformation. Three key issues including the explicit expression of the free energy density, the predetermination of the initial elastic deformation, and the initial residual stress are addressed.Finally, we consider a tubular organ as a representative example to demonstrate the effects of the proposed initial residual stress on stress distribution and on shape formation through an incremental stability analysis. Our results suggest that the initial residual stress exerts a major influence on the growth stress and the morphology of biological tissues. The model bridges the gap between any two growth states of a biological tissue that is endowed with a certain level of residual stresses. (C) 2018 Elsevier Ltd. All rights reserved. This work was supported by the National Natural Science Foundation of China through grant Nos. 11621062 and 11772295, and was also partly supported by the Fundamental Research Funds for the Central Universities 2016XZZX001-05. peer-reviewed 2020-05-19

Micro-machining techniques are generating considerable interest in manufacturing industries. Photochemical machining (PCM) is one of such techniques in which the material is etched with the help of etchant in the controlled corrosion process. Machining area is defined by application of photoresist layer over the material, which ensures the removal of desired area. This process is regarded as stress free machining in which no mechanical stress is imposed on the workpiece while machining. Achieving accuracy in the PCM process is one of the prime challenges to overcome. Material removal and accuracy of PCM process can be enhanced by selecting proper positioning of workpiece inside the etching tank and preparing accurate photo-tool. This paper investigates various modes of workpiece positioning and their effect on material removal mechanism and determines most suitable positioning of workpiece to enhance performance of PCM process. An attempt to attain accurate photo-tool has also been presented in this paper.

In this investigation, general approximate solutions for the stress intensity factor (SIF) and configuration force (CF) are derived, respectively, based on the Eshelby theory for the interaction between an inhomogeneous inclusion of arbitrary shape undergoing a stress-free transformation strain and plane stress mode II crack. For common inclusion shapes, some simplified approximate formulae are also developed. Then, the relationship between the normalized CF and SIF is discussed, as well as the effects of inclusion shape, location, and size on the CF and SIF of a plane stress mode II crack. To give deep insight into the complex three-dimensional interaction between an inclusion undergoing a stress-free transformation strain and a crack, two typical cases of the triaxial stress state are analyzed, and no significant difference occurs among most engineering materials.

In this paper, case wise studies have been made to investigate the possibility of propagation of Rayleigh-type wave in a composite structure comprised of two transversely-isotropic material layers with viscoelastic effect. The common interface between the layers is considered to be rigid whereas the base has been considered as rigid, stress-free and yielding in three different cases (Case-I, II and III). Closed-form of frequency equation and damped velocity equation has been established analytically for propagation of Rayleigh-type wave in a composite structure for all three cases. In special cases, frequency equations and damped velocity equations for the case of composite structure with rigid, stress-free and yielding base have been found in well-agreement to the established standard results pre-existing in the literature. Numerical and graphical computation of phase and damped velocity of Rayleigh-type wave propagating in the composite structure comprised of double transversely-isotropic viscoelastic Taylor sandstone material layers (Model-I) and double isotropic viscoelastic material layers (Model-II) have been carried out. Significant effect of anisotropy and width ratio of layers, dilatational and volume viscoelasticity associated with viscoelasticity of layer medium and yielding parameter associated with yielding base of composite structure on phase and damped velocities of Rayleigh-type wave for the considered models have been traced out. The comparative study has been performed to unravel the effect of viscoelasticity over elasticity and anisotropy over isotropy in the present problem.

Stress-free InN nanowires (NWs) have been grown on Au/graphene/GaN/sapphire substrate by atmospheric pressure metal-In sublimation method. The phonon E2(high) and A1(LO) mode in Raman spectra of InN grown on graphene is observed at 490.8 and 585 cm−1 respectively, which is similar to that of bulk InN. The high resolution TEM (HRTEM) image of InN NWs shows that the interplanar spacing of (0 0 0 2) and (1 1 −2 0) are 2.85 A and 1.77 A, which is according with the XRD result. All the results confirm that Au-catalyst assists the growth of InN NWs, and the stress is released by the aid of the graphene inter-layer.

Aiming at the serious deformation problem of composite after curing, a new curing technology based on tool-part thermal expansion matching and stress-free temperature theory is presented to reduce the deformation. The thermal expansions of composite tool are designed to match with the composite part in parallel and perpendicular to the fiber direction. The stress-free temperature theory is introduced to reduce chemical shrinkage of resin by modifying the curing parameters. To verify the accuracy of this technology, the deformation of composite samples manufactured by traditional and the new curing technologies are compared. The experiment results indicate that the deformation of composites cured by the new curing technology is reduced to 8.3 % of traditional curing process.

Nematic liquid crystals combined with long molecular chains to form liquid crystal elastomers are capable of large extension. When such liquid crystal elastomers contain azo dyes to constitute photoelastomers, illumination can trigger large contraction. Beams made from such photoelastomers possess a non-uniform illumination and hence photostrain across their cross-section, resulting in bending and highly non-linear stress distribution. Due to the non-linear stress distribution, there can be more than one stress-free layers within the beam. In this paper, we present a dimensionless parametric study of nematic photoelastomer beams under the combined effects of light and mechanical loads. We show how the number of stress-free layers depends on three dimensionless parameters. The paths traced out by the system in the space of dimensionless parameters by varying the different real parameters are investigated, showing how the number of stress-free layers changes when e.g. the thickness or the mechanical load of the elastomer beam is varied. These results are important if the strain induced director rotation is not negligible.

Continuous welded rail (CWR) is a fundamental component of any modern track structure and has several advantages over former types of rail joining processes. The reduction in maintenance and related costs has become the most attractive property of CWR although careful monitoring and maintenance of CWR is essential to ensure safe train operations. Management of the stress-free temperature (SFT) of any section of CWR in order to prevent rail breaks and lateral buckling that could lead to derailments is a vital duty of the track maintenance team. Variations in the SFT are influenced by a number of external factors. This paper describes experimental field and laboratory tests carried out to investigate to what extent the fastening strength influences the variation in SFT in CWR track on Fist fastenings and two types of pads. The research established a nonlinear relationship between clamping force and rail movement through the fasteners as well as a strongly linear relationship between clamping force and the variation in SFT. It is also demonstrated that although the friction coefficient of the pad has an influence on rail movement through the fastener, the primary factor influencing SFT variations is the clip force. This paper concludes by quantifying the relationship between clamping force and the expected variation in SFT with clear guidelines on the management of the SFT in CWR.

Thermal neutrons are very useful probe in a nondestructive determination of internal stress/strains, due to their high penetration into most materials. In comparison with conventional X-ray techniques, real bulk information on both macro-and micro-strains in materials can be obtained by neutron diffraction (ND) techniques. Knowledge of the spatial and directional distribution of internal residual stresses (RS) is increasingly considered fundamental to determine their influence on properties of engineering materials and a consequent material behaviour. As the assesment of stresses is always related to the stress free material state, an accurate evaluation of the unstressed lattice parameters (e.g., the interplanar distance), in order to determine RS by ND is one of the key tasks. It helps to avoid inacceptable errors in the course of the real material strain and stress evaluation. The availability of carefully measured zero-strain standards is also essential to confirm the absence of systematic instrumental effects determining the diffraction profile at a chosen scattering angle. In this paper, the state of the art of the main analytical and experimental procedures currently established or adoptable to determine these critical parameters, particularly regarding industrial applications, is presented.

A study is undertaken to investigate the fatigue crack growth rate properties of polycrystalline IN100 through the identification of crack growth mechanisms as a function of temperature, frequency and ΔK. An additional goal is to determine the stress free activation energy of IN100. Constant amplitude, load controlled tests are performed at room temperature (22 °C), 316 °C, 482 °C and 649 °C under two different loading frequencies of 20 and 0.33 Hz. These specimens are then analysed via scanning electron microscopy (SEM) to determine failure mechanisms. SEM shows that, as temperature increased from room temperature to 649 °C, the fracture mechanism transitions from transgranular to intergranular. The fracture mechanism is shown to transition from intergranular to transgranular at elevated temperatures as da/dN increases as a result of growing ΔK. Scanning electron microscopy shows that, as frequency decreases from 20 to 0.33 Hz at 649 °C, the fracture mechanism transitions from transgranular to intergranular.

Governing equations of thermoelastic diffusion material with voids are modified with the help of Lord and Shulman theory of generalized thermoelasticity. These governing equations are then solved in two-dimension to show the existence of four coupled longitudinal waves and a shear wave. The complex absolute values of the speeds of the coupled longitudinal waves are computed numerically against the frequency for Magnesium material. The reflection of these plane waves from a stress free thermally insulated boundary is also studied, where the dependence of the reflection coefficients on angle of incidence is shown graphically for the incidence of coupled longitudinal wave only. The speeds and reflection coefficients of plane waves are also computed numerically in the absence of voids and diffusion parameters, which are shown graphically to observe the effects of voids and diffusion.

When neutron diffraction is used to measure residual stresses, estimates of the unstressed lattice spacing ( d0) are often required. These are generally measured on a sample that is considered representative of the component. In the case of welded samples, the possibility of variation in weld shape between the d0 sample and the area where stresses are determined must be taken into account. To assess this, d0 values are measured on an area considered representative of the sample, and then are re-measured on a sample cut from the actual strain measurement plane. The residual stresses are re-calculated with these new d0 values and the results compared to those based on the initial d0 measurement. Methods of estimating these errors are discussed. The errors in residual stress that arise from the spatial variation of d0 values are greater than the commonly reported peak fitting errors. These errors can be estimated and should be included in the reported residual stress measurements. Cutting a d0 sample from the measurement plane makes this a destructive technique.

In this paper, the integration of HfO2 onto SiC has been investigated via a number of different test structures. Capacitors consisting of HfO2 on Si, SiC, Si/SiC and SiO2/SiC have been fabricated and electrically tested. The new HfO2/Si/SiC capacitors provide the greatest breakdown electric field of 3.5 MV/cm, whilst leakage currents are minimised through the insertion of the narrow bandgap material. The Si layer, which is wafer bonded to the SiC, is proven to be stress free through Raman spectroscopy, whilst TEM and EDX prove that the interface is free of contaminants.

The propagation of circularly crested thermoelastic diffusive waves in an infinite homogeneous transversely isotropic plate subjected to stress free, isothermal/insulated and chemical potential conditions is investigated in the framework of different thermoelastic diffusion theories. The dispersion equations of thermoelastic diffusive Lamb type waves are derived. Some special cases of the dispersion equations are also deduced.

The influence of the peak determination method on the area detector type neutron stress measurement method was investigated. Two peak determination methods, the half value breadth method and the centroid method, were compared and discussed in this paper. Experiments and simulation studies were carried out respectively. The first experiment was conducted during the tensile stress test with a steel specimen having the thickness of 6mm, and the second experiment was conducted with steel specimens in the stress free state having the thickness between 1 mm to 20 mm. As a result of the experiments, it was found that the peak determination method has an affect on the area detector type neutron stress measurement. A numerical simulation study was also conducted and showed similar result as the experiments.

The bimaterial cantilevers are frequently used in microsensors and microactuators. A bimaterial element consists of two layers of materials with different physical properties and/or deposited under different conditions. For this reason, mechanical stresses of various origins appear along the layers and between them, causing initial deformation of the cantilever. Further, a necessary condition for the optimum response of a bimaterial cantilever to an external stimulus is that Young's moduli of both layers are approximately equal. In thermal cantilever-based actuators commonly met in practice, the first layer is usually made of SiO2, PolySi, or SiNx, whereas the second is made of Al or Au. The Young's moduli of these materials differ significantly and thus the maximum sensitivity is difficult to achieve. To ensure the planarity of the free cantilever, the common goal during fabrication is to obtain low internal stresses within both layers, which sometimes represent a severe technological limitation in high-temperature processes. This work presents a new method of stress compensation between the bimaterial cantilever layers. SiO2, PolySi, or SiNx are still used for the first layer, whereas nickel is used for the second layer. Nickel has many advantages and favourable mechanical properties compared with previously used aluminium and gold.

This study investigated the complete history of residual stress evolution in a stress-free titanium alloy, Ti–6Al–4 V under fretting fatigue loading condition. Compressive residual stress developed in the contact region due to the local plastic deformation between contacting bodies. The compressive residual stress then increased initially with increasing number of fretting fatigue cycles reaching to a maximum value, and then it decreased (or relaxed) with further cycling. This relaxation of compressive residual stress was due to the delamination and detachment of flake-like (wear sheet) material in the fretted region.

Stress/strain determination by x-ray or neutron diffraction means always to measure lattice plane distances in different direction and then to solve a system of simultaneous, linear equations. The number of unknowns and equations needed is up to six, but can be smaller if there is already some information about the stress/strain state, e.g. if principal axes are known or if there is a stress free surface. No matter how many equations one has to solve, the accuracies of the calculated unknowns depend not only on the accuracies of the measured lattice plane distance but also very much on the geometrical relationships among the measurement directions. Therefore the whole measurement must be thoroughly planned, it is that the measurement directions must be choosen thoroughly. In the case of a textured or a single crystalline material this is quite difficult and should be done using computer programs. Such programs are introduced together with some examples.

It is shown that, if an elastic material exhibits two stress-free configurations, it is dynamically unstable in a definite sense.

We consider the problem of dynamic cavity formation in isotropic compressible nonlinear elastic media. For the equations of radial elasticity we construct self-similar weak solutions that describe a cavity emanating from a state of uniform deformation. For dimensions $d =2, 3$ we show that cavity formation is necessarily associated with a unique precursor shock. We also study the bifurcation diagram and do a detailed analysis of the singular asymptotics associated to cavity initiation as a function of the cavity speed of the self-similar profiles. We show that for stress free cavities the critical stretching associated with dynamically cavitating solutions coincides with the critical stretching in the bifurcation diagram of equilibrium elasticity. Our analysis treats both stress-free cavities and cavities with contents., Comment: 49 pages

A new ultrasonic evaluation method of axial load is proposed for short and highly stressed bolts used for automobiles. The velocity-ratio method need not require time-of-flight measurement under stress free state, however, a considerable error is caused by the variation of bolt length which is unknown in the practical measurement. The proposed method estimates the bolt length variation and reduces the error of the axial load due to this variation. Based on the measured relations of the axial load with the time-of-flight of longitudinal and transverse waves, the variation of the unknown bolt length is estimated. By this correction, the variation of the axial load can be reduced to a half of those measured.

A new method is introduced to measure the dimensional changes of the polymeric resins while they go through the curing process. The dimensional change of the resin can be detected by implanting two markers into the resin and looking at the relative movement of them under an optical microscope. In the next part of this study, a partially-filled polymer specimen was made with continuous fibers. The measurement of the residual strain in the un-reinforced polymer phase of the specimen and comparison of it to the shrinkage value, indicated that only 3.3% of the resin shrinkage remained as residual strain in the polymer. Furthermore, the reheating of the bi-layer sample revealed that the stress free temperature is much lower than the curing temperature of the composite.

In this paper, the Landau-Ginzburg equation is derived for the two-dimensional deep Benard convection equations with stress free boundaries.

A penny-shaped crack is considered under the action of radial shear in a thick transversely isotropic elastic layer. The external faces of the layer are stress free. Employing the Dugdale hypothesis and Hankel transform theory, the problem of determining the size of the plastic zone is reduced to the numerical solution of a Fredholm integral equation of the second kind. Graphical results showing the effect of transverse isotropy upon the width of the plastic zone are presented and compared with results obtained for isotropic material.

Residual stress measurements using neutron diffraction are inherently triaxial in nature due to the low adsorption, and thus high penetration, of neutrons in samples of interest. This means that stress-free reference standards are required to convert measured changes in peak position to strain and stress tensors. Althogh a number of empirical and analytical approaches have been utilized to obtain accurate stress-free reference cell parameters, they all presume the presence of a single reference value for the material being measured. However, important cases can arise for which the local stress-free cell parameter varies from point to point. One such case, a circumferentially welded cylinder, is presented here. A method of point-to-point correction is employed, involving the sectioning of a companion piece into small cubes corresponding to the positions of stress measurement. The variations in peak position and peak breadth are presented. It is shown that accurate stress tensors can be obtained and that use of a constant value of stress-free reference cell parameter from the unaffected base metal leads to errors of up to 700 MPa in some stress tensor components. Effects on the principal stresses are also presented.

Part III of this work is concerned with the interaction of two penny-shaped cracks in the mid-plane of an elastic layer. Two cases, namely the stress free boundary case and the fixed boundary case, are considered. It is shown that these two cases are mathematically equivalent. As in Part I (G.A.C. Graham and Q. Lan, J. Theor. Appl. Fract. Mech. 20, 207–225 (1994) [1])_for the problems of an infinite solid and Part II (G.A.C. Graham and Q. Lan, J. Theor. Appl. Fract. Mech. 20, 227–237 (1994) [2]) of a semi-infinite solid, the problem is reduced to a system of Fredholm integral equations of the second kind. These integral equations are then solved when the crack size is small compared to the distance between them and the cracks are far away from the boundaries. It is also shown that the problem decouples when the cracks are subjected to normal loading and shear loading. Asymptotic solutions are presented for these two loadings.

The wave propagation in an infinite poroelastic cylindrical bone with cavity is studied. The frequency equation for poroelastic bone is obtained when the boundaries are stress free and is examined numerically. The dimensionless wave numbers are calculated for poroelastic bone for various values of non-dimensional frequencies and are given in a table and graphs. The dispersion curves are plotted for poroelastic and purely elastic behavior of the bones.

The equilibrium shapes of stress free inclusions with a small mismatch and possibly a small rotation from the matrix phase are studied. The model used includes both bond-breaking and elastic contributions to the interface energy. The unrotated shape contains only facets. Rotated inclusions sometimes contain smoothly curved parts as well. Interface phase diagrams are used to characterize the stable phase behavior of flat interfaces of fixed orientation.

Considered in this work is the stress solution of a finite length crack near a traction free parabolic notch. Uses are made from the solution of a crack subjected to arbirary surface tractions and that of concentrated forces in a plane with a parabolic notch. Superposition of the two problems corresponding to stress free conditions on the crack and notch leads to a singular integral equation that can be solved numerically for the crack tip stress intensity factors. Two specific examples are discussed. The first pertains to a pair of concentrated forces in the region across the crack and the second case involves isolated forces applied to the boundary of the parabolic notch. The distances between the crack and notch and location of the load are changed to exhibit the corresponding variations in the stress intensity factors. Discussed are the failure behavior of a notch with a line crack defect ahead.

The transformation of δ ferrite in type 316 stainless steel weld metal during creep deformation at 823, 873, and 923 K has been investigated. The extent of transformation, as measured using a Magne-gauge, has been found to be greater under the influence of applied stress. The rate of transformation follows the Johnson–Mehl equation both for stress assisted and for stress free conditions.MST/1274

There are several problems wherein it would be convenient to have representations for the stress from a stressed configuration as reference. We assume that the body undergoes finite elastic deformations (i.e., non-dissipative processes) from a stressed reference configuration but it is possible that a dissipative (inelastic) process could be the cause for the origin of the stresses in the reference configuration. We restrict ourselves to determining the representation for the stress in a body, from a stressed reference configuration, whose symmetry group in the stress free configuration (that is accessible from the stressed reference configuration) coincides with the full orthogonal group. We also find restrictions on the constitutive relation so that we have a model that exhibits physically acceptable response characteristics. � 2008 Elsevier Ltd. All rights reserved.

The corrosion behaviour of the austenitic 32Ni-20Cr steel Alloy 800H was investigated in several S-O-C bearing gas mixtures simulating coal gasification environments at 700°C for up to 5000 h. It is shown that relatively small changes in oxygen and sulphur activities can cause a significant change in corrosion behaviour. Moreover creep deformation leads to a marked enhancement of the corrosive attack which takes place particularly along grain boundaries lying perpendicular to the stress axis. Korrosions- und Kriechverhalten der Leigierung Alloy 800H in sulfidierend/oxidierend/aufkohlenden Atmospharen bei 700°C – Teil I: Korrosionsverhalten im spannungsfreien Zustand und unter Spannung Das Korrosionsverhalten des austenitischen Stahls 32Ni-20Cr (Alloy 800H) wurde in verschiedenen S-O-C-haltigen Gasgemischen untersucht, welche die bei der Kohlevergasung auftretenden Atmospharen simulierten; die Versuchtemperatur betrug 700°C, die Versuchsdauer bis 5000 h. Es wurde gezeigt, das schon verhaltnismasig geringe Veranderungen der Sauerstoff- und Schwefelaktivitat das Korrosionsverhalten betrachtlich verandern konnen. Daruber hinaus fuhrt Kriechverformung zu einer ausgepragten Verstarkung des Korrosionsangriffs, vor allem an den zur Spannungsachse senkrechten Korngrenzen.

Previous measurements by other investigators of the purely viscous properties of viscoelastic fluids using the falling ball viscometer have been shown to yield anomalous results. These occur because the ball falling through the viscoelastic fluid creates a stress field which requires up to one hour to relax to its stress free state before another ball can be dropped. This is experimentally inconvenient. To further investigate this effect for a variety of viscometers, time interval measurements were made on a viscoelastic fluid (AP-273 Separan) using falling ball, falling needle and rotating cylinder viscometers. Although the falling ball measurements showed considerable time interval effects, the falling needle and rotating cylinder measurements did not. Thus the falling needle and rotating cylinder viscometers can be used to conveniently measure the steady shear viscosity of viscoelastic fluids.

Thin composite films containing inclusions are commonly being developed as corrosion resistant, wear resistant coatings and so forth. For systems where the composite film is under residual stresses properly designed, a controlled debonding process of the inclusions can be used to reduce the stress levels in the film lowering the risk of through cracks in the film as well as the risk for the film's delamination from the substrate. In this paper, on the basis of the Eshelby equivalent inclusion theory, a general solution is derived by treating an inhomogeneous inclusion as a homogeneous one with transformation strain for the configuration force (CF) and stress intensity factor (SIF) between mode I crack and an inhomogeneous inclusion of arbitrary shape which undergoes some degree of stress-free transformation strain under plane stress loading conditions. Then the CF associated with the transformation is calculated from the work done during the transformation, from which some simplified approximate formulae are also presented for common inclusion shapes in order to provide a quick estimate for the effects of inclusion shape, location and size on the CF of plane stress model I crack. In comparison to conventional numerical approaches, the present solution provides a novel approach to explain the behavior of crack deflection/penetration and can be used for the optimization design of the composite films.

In a recent communication, James and Zhang proposed four criteria for hysteresis width minimization for alloys exhibiting a first order solid–solid phase transformation. In the present work, four different phase transformations are investigated through four different alloys: cubic → trigonal R-phase for NiTi, cubic → monoclinic II for Cu–Zn–Al, cubic → monoclinic I for NiTi and cubic → tetragonal for Ni–Mn–Ga. The first aim of this paper is to validate the efficiency of these four criteria of reversibility. The second aim of the paper is to show how the crystallographic theory of martensite, built to predict microstructure under stress free state or dead loads, can be used for continuous loadings. Except for Ni–Mn–Ga, the criteria predictions are in good agreement with the experimental observations and with the choice of the Helmholtz free energy function expression.

This program enabled a comparison of the electromechanical measurements on high strain piezoelectric single crystal materials between groups at Alfred University, TRS Ceramics, the Royal Military College of Canada, the Naval Undersea Warfare Center, and Penn State University. This work focused on the measurement of field-induced polarization and strain in single crystal PZN-PT and PMN-PT under nominally stress free conditions. The objective of this work was to assess the effect of measurement technique on the observed behavior of these two single crystals. The research enabled a test of the applicability of a protocol for the derivation of small and large signal dielectric constants from the polarization versus field curves and the small and large signal piezoelectric coefficients from the strain versus field curves. Two PZN-PT compositions (4.5% PT and 8% PT), and two PMN-PT compositions (30% PT and 25-28% PT) were characterized. It was found that the different groups showed generally very good agreement in the measured properties.