摘要:

This article focuses on the derivation of constitutive equations for creep of polycrystalline materials. According to the suggested analytical model, creep deformation reflects the simultaneous evolution and interaction of two distinctly different (viscous vs brittle) processes on the microscale. The formulated analytical model is valid over the entire range of ductility, from the perfectly brittle to the purely ductile materials.

ISSN:0360-1218    

DOI:10.1080/03601218308907428

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

ISSN:0360-1218    

DOI:10.1080/03601218308907426

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

ISSN:0360-1218    

DOI:10.1080/03601218308907427

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Transient waves propagating parallel to the layers in a linear elastic or viscoelastic layered composite are studied. A step load in time is applied at the boundaryx = 0 and the head-of-the-pulse asymptotic solution is obtained for largexand large timet. For viscoelastic composites the interaction between the dissipation and the dispersion is controlled by a parameter γ that contains the material mismatch of the layers and the distance: propagated by the waves. As the distance increases, so does γ, and the oscillatory response diminishes. For elastic composites, we show how the oscillatory response depends on the mismatch of the material properties and the thicknesses of the layers. We show that there are composites other than the one with zero mismatch for which the oscillatory response is almost nonexistent.

ISSN:0360-1218    

DOI:10.1080/03601218308907429

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Symmetric and nonsymmetric buckling solutions are obtained for an axially compressed half space. The half space is assumed to be made of a general in compressible isotropic elastic material. Solutions are made possible via the use of a direct approach that does not employ conventional Fourier-analysis calculations.

ISSN:0360-1218    

DOI:10.1080/03601218308907430

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Hybrid-stress isoparametric finite elements are developed for the analysis of thin plates utilizing independent interpolations for transverse displacement and cross-section rotations. The formulation is based on earlier hybrid-stress plate elements that utilize Mindlin-type displacement fields and include transverse shear stress and transverse normal stress contributions. By neglecting the contributions of transverse shear and normal stresses to the complementary strain energy, isoparametric thin plate elements are obtained that have the same performance characteristics as the non-reduced element in the thin plate limit. This is illustrated for a two-node beam element. In addition to the ease of formulating isoparametric thin plate elements usingC°displacement interpolations, the primary advantage of this approach over the nonreduced element is the significant savings of computation time for element stiffness generation that is made possible. Computational considerations are illustrated for an 8-node invariant isoparametric plate element.

ISSN:0360-1218    

DOI:10.1080/03601218308907431

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

For a viscoelastic beam or frame structure that undergoes forced vibrations, the conditions for optimal support reaction are derived. Translation or rotation of supports are allowed and a functional expressed in terms of stress or strain amplitudes is minimized. Optimality conditions are derived using the concept of an adjoint structure and an illustrative example is presented for the case of beam vibration.

ISSN:0360-1218    

DOI:10.1080/03601218308907432

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Shallow, linearly elastic arches of unspecified form but with given uniform cross section and material are considered. For given span and length of the arch, two different optimization problems are formulated and solved. In the first, we determine the form of the arch which maximizes the fundamental vibration frequency. The corresponding vibration mode turns out to be either symmetric or antisymmetric. In the second, a static load with given spatial distribution is considered, and the critical value of the load magnitude for snap-through instability is maximized. This instability may occur at a limit point or a bifurcation point. Optimal forms are determined for sinusoidal loading, uniform loading, and a central concentrated load. In both types of problems, arches with simply supported or clamped ends are considered, and the maximum frequencies and critical loads obtained are compared to those for a circular arch with similar end conditions. In all the cases with simply supported ends, it is found that a circular arch is almost optimal. For clamped ends, however, it turns out that the optimal arches have zero slope at the ends and that they are much more efficient than a circular arch.

ISSN:0360-1218    

DOI:10.1080/03601218308907433

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Singular situations in minimum-volume elastic design are analyzed and illustrated as they occur in optimization of a three-bar truss. Relations between minimum-volume design with bounds on stress intensity, assigned load factor at collapse, and assigned elastic compliance are analyzed.

ISSN:0360-1218    

DOI:10.1080/03601218308907434

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

A variational formulation is presented for shape optimal design of two-dimensional elastic bodies. Optimal modification or remodel of a specified shape is determined for reinforcing (addition of material), lightening (removal of material), or redistribution of material by a specified amount. Necessary conditions are obtained in analytical form to provide the basis for an algorithm to solve the optimal remodel design problem computationally. The method is demonstrated for examples in both torsion and plane stress problems, including cases in which the optimal modification calls for introduction of a hole into an original shape.

ISSN:0360-1218    

DOI:10.1080/03601218308907435

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor