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This paper presents a review concerning the analytical and inverse methods of small punch creep test (SPCT) in order to evaluate the mechanical property of component material at elevated temperature.

In this work, the effects of temperature, specimen size and shape on material properties are mainly discussed using the finite element (FE) method. The analytical approaches including membrane stretching, empirical or semi-empirical solutions that are currently used for data interpretation have been presented.

The state-of-the-art research progress on the inverse method, such as non-linear optimization program and neutral network, is critically reviewed. The capabilities of the inverse technique, the uniqueness of the solution and future development are discussed.

The state-of-the-art research progress on the inverse method such as non-linear optimization program and neutral network is critically reviewed. The capabilities of the inverse technique, the uniqueness of the solution and future development are discussed.

The aim of the presented research is to apply the method of punch deformation for the simulation of textile systems behaviour in serve conditions and on the basis of it create original method and find new criteria for shape stability evaluation. The research was done with the help of three devices of punch loading originally created at Kaunas University of Technology (Lithuania), which were attached to the standard tensile testing machine. Creep tests were performed by a special device, clamping radius of which was R=56.5 mm. Creep process was controlled up to the stabilisation of shells height, i.e. after t=48 h. Tests were carried out in wet and dry states of the specimen. Two different types of textile systems (I+K and K+I) composed of two layers were investigated (where K – outer material; I – interlining).

This paper aims to develop the methodology for the imitation of exploitation conditions of textile products as well as to determine the exploitation peculiarities of high‐performance fabrics for outdoor clothing producible in Lithuania.

Static‐ and dynamic‐cyclic loading was applied for the imitation of exploitation conditions as well as for the investigation of the changes in specimen geometrical parameters.

The differences in the parameters of textile material stability determined under dry and wet cyclic specimen deformation were determined. The investigation results presented show that the parameters of air permeability can be used for the determination of changes in textile product shapes due to their cyclic washing as well as to the other kinds of wet technological treatment, especially in these cases when the small areas of product material are deformed.

The problems concerned with the methodology for the evaluation of exploitation stability of high‐performance fabrics (woven and knitted) for outdoor clothing are analyzed in this research.

In most cases, the exploitation behaviour of textile materials is investigated under uniaxial or static biaxial deformation. For better imitation of real exploitation conditions of textiles the new testing methodology based on two testing methods was established (original device for punch deformation working in creep mode as well as using wet and dry specimens; device ARRV for cyclic fatigue).

The goal of this research work was experimental investigation and evaluation of biaxial punch deformation processes of anisotropic textile materials. The investigation was aimed to solving the following problems: tofind a new criterion for textile behaviour evaluation in punch loading; to evaluate theeffect of material anisotropy for the geometry offormed shell; to determine the straindistribution in anisotropic shell. The experimental data of X‐ray diffraction analysis showed that friction at specimen/punch contact, which earlier was ignored, has a significant effect upon the parameters of the punching process.

The objective of this paper is to construct a continuous model for the thermo‐visco‐elastic contact of a nominal flat, non‐smooth, punch and a smooth surface of a rigid half‐space. The considered model aims at studying the normal approach as a function of the applied loads and temperatures. The proposed model assumes the punch surface material to behave according to the linear Kelvin‐Voigt visco‐elastic material. The punch surface, which is known to be fractal in nature, is modeled in this work using a deterministic Cantor structure. An asymptotic power low, deduced using approximate iterative relations, is used to express the punch surface approach as a function of the remote forces and bulk temperatures when the approach of the punch surface and the half space is in the order of the size of the surface roughness. The results obtained using this model, which admits closed form solution, are displayed graphically for selected values of the system parameters; the fractal surface roughness and various material properties. The obtained results showed good agreement with published experimental results.

The purpose of this paper is to derive the exact analytical expressions for torsion and bending creep of rods with the Norton-Bailey, Garofalo and Naumenko-Altenbach-Gorash constitutive models. These simple constitutive models, for example, the time- and strain-hardening constitutive equations, were based on adaptations for time-varying stress of equally simple models for the secondary creep stage from constant load/stress uniaxial tests where minimum creep rate is constant. The analytical solution is studied for Norton-Bailey and Garofalo laws in uniaxial states of stress.

The creep component of strain rate is defined by material-specific creep law. In this paper the authors adopt, following the common procedure Betten, an isotropic stress function. The paper derives the expressions for strain rate for uniaxial and shear stress states for the definite representations of stress function. First, in this paper the authors investigate the creep for the total deformation that remains constant in time.

The exact analytical expressions giving the torque and bending moment as a function of the time were derived.

The material isotropy and homogeneity preimposed. The secondary creep phase is considered.

The results of creep simulation are applied to practically important problem of engineering, namely for simulation of creep and relaxation of helical and disk springs.

The new, closed form solutions with commonly accepted creep models allow a deeper understanding of such a constitutive model's effect on stress and deformation and the implications for high temperature design. The application of the original solutions allows accurate analytic description of creep and relaxation of practically important problems in mechanical engineering. Following the procedure the paper establishes closed form solutions for creep and relaxation in helical, leaf and disk springs.

This work aims at constructing a continuous mathematical, linear elastic, model for the thermal contact conductance (TCC) of two rough surfaces in contact.

The rough surfaces, known to be physical fractal, are modelled using a deterministic Cantor structure. Such structure shows several levels of imperfections and including, therefore, several scales in the constriction of the flux lines. The proposed model will study the effect of the deformation (approach) of the two rough surfaces on the TCC as a function of the remotely applied load.

An asymptotic power law, derived using approximate iterative relations, is used to express the area of contact and, consequently, the thermal conductance as a function of the applied load. The model is valid only when the approach of the two surface in contact is of the order of the surface roughness. The results obtained using this model, which admits closed form solution, are displayed graphically for selected values of the system parameters; the fractal surface roughness and various material properties. The obtained results showed good agreement with published experimental results both in trend and the numerical values.

The model obtained provides further insight into the effect that surface texture has on the heat conductance process. The proposed model could be used to conduct an analytical investigation of the thermal conductance of rough surfaces in contact. This model, although simple (composed of springs), nevertheless works well.

WORK STUDY still suffers from the unenviable reputation it gained in its early days when it was regarded as little more than a device, tinged with a touch of duress, for getting a greater output from the manual worker on the shop floor. This legacy of dislike still erupts occasionally in unexpected ways.

THE Greater London Council's conference hall, which can hold several hundred people, was packed to capacity in the evening of March 3. The suspicion that it was a mass gathering to hear a party leader expound national issues was only dispelled by a realization that it was a trifle easy.

This work addresses the computational aspects of a model for elastoplastic damage at finite strains. The model is a modification of a previously established model for large strain elastoplasticity described by Perić et al. which is here extended to include isotropic damage and kinematic hardening. Within the computational scheme, the constitutive equations are numerically integrated by an algorithm based on operator split methodology (elastic predictor—plastic corrector). The Newton—Raphson method is used to solve the discretized evolution equations in the plastic corrector stage. A numerical assessment of accuracy and stability of the integration algorithm is carried out based on iso‐error maps. To improve the stability of the local N—R scheme, the standard elastic predictor is replaced by improvedinitial estimates ensuring convergence for large increments. Several possibilities are explored and their effect on the stability of the N—R scheme is investigated. The finite element method is used in the approximation of the incremental equilibrium problem and the resulting equations are solved by the standard Newton—Raphson procedure. Two numerical examples are presented. The results are compared with those obtained by the original elastoplastic model.