Traditional thermal stresses analyses consider thermal load as static load or quasi static load. When the temperature field of the structure varies drastically,these analyses can not satisfy the real need. A finite element method is presented for solving the response of structure under dynamic thermal load (including thermal impulse).

Quasi static load, wave moment composing, main methods of linear and nonlinear hydroelasticity,symmetry and unsymmetry response, frequency/time domain solutions, slamming response, random wave load are discussed systematically.

Results and Conclusion The experiment on the pressured pipeline under quasi static load has established a theoretic foundation for the analysis. Reliable analytic method and improtant technical parameters are provided for the evaluation of impact robustness of high pressured pipeline with fluid medium and their safety design.

The experimentally verified quasi-static load sharing is incorporated into a Monte Carlo simulation for tensile strength modeling.

The crashworthiness requirements are sub-divided into static/quasi-static load requirements and CEM requirements.

In order to determine suitable quasi-static load levels, several specimens were subjected to a series of increasing quasi-static loads.

Each of the three spans was tested to failure by applying quasi-static load cycles.

Each of the three decks was tested to failure by applying quasi-static load cycles.

A difficult element of the classical plasticity theory is the concept of the yield surface which leads to experimental and numerical difficulties when attempting to describe and analyze the two or three dimensional response of a material, valanis circumvented this difficulty by developing the theory of endochronic plasticity which does not require the concept of yield for the description of plastic behavior of materials. Recently considerable attention has been paid to the validity, computational capability...

A difficult element of the classical plasticity theory is the concept of the yield surface which leads to experimental and numerical difficulties when attempting to describe and analyze the two or three dimensional response of a material, valanis circumvented this difficulty by developing the theory of endochronic plasticity which does not require the concept of yield for the description of plastic behavior of materials. Recently considerable attention has been paid to the validity, computational capability .and predictive power of the endochronic plasticity, which is caused mainly by the fact that all applications of the theory have, so far, been limited to the homogeneous fields in quasi-static loading. To circumvented the mathematical difficulty for application of the endochronic constitutive equationwhere z is intrinsic time scale and p(z)a kernel function with weak singularity of the origin, an new endochronic elastoplastic constitutive equation has been develot ped. keeping in mind that the derivative of the heaviside step function H(z)is the Dirac delta function δ(z) andThen we can approximately take ρ(z) asThis form of ρ(z) is continuous and differentiable in (0,∞). we, therefore, can obtain the following new elastoplastic endochronic constitutive equationEq. (4) is a three dimensional constitutive equation, which can be specified and expressed as matrix form in. terms of {σ}, {ε} and {h} for particular case. Take plane problem as an example it can be reduced to eq. ( 5 ) by supposing the plastic incompressibility,where{D}is an adequate approximation to the elastic matrix{E}, {H}is a nonlinear part of eq. ( 5 ), which is history dependent and determined by z, ρ(z) and hardening function f(ζ). It was found that three terms in eq. ( 3 )suffice to describe the material response and ct, ai can be determined by the curve fitting in the following region from simple tensile test.over which ρ(z)decays very fast from singularity to a negligible value, while f(ζ)is a well-behaved slowly varying function and can be determined outside the region .A numerical algorithm based on the finite element method of analysis of the boundary value problem in a continuum is presented, in the case where the elastoplastic response of the material is given by the new constitutive equation. It was found that this algorithm is more convenient for calculation than that of classical plasticity, in which the concept of yield surface has taken a very important role.By designing a special experiment and a finite element mesh(the smallest gague and element are equal in size and about 0.2 mm), the validity of the new elastoplastic constitutive eqation of the endochronic plasticity and the algorithm developed in this work are tested in the case of a complex boundary value problem nvolving a highly heterogeneous elastoplasiic strain field in a reclangi lar plate, with notches symmetrically placed with respect to longitudinal axis of symmetry. The plates were loaded cyclically in the direction of this axis .Excellent agreemen between experimental and calculated results is shown along two perpendicular direct i ,r.s in the notch tip for a cyclic history up to three reversals.The present results could have a wide scope of application in different branches of solid mechanics, for instance, elastoplastic structure analysis, fracture and fatigue. The examples of the applicaticn and some predicted and verified new phenomenon will be reported later.The work was finished under the guidance of Professor R. C. valanis, the author would like to express his deepst gratitute to him.

The authors arc quite certain that there do not exist previously published experimental data onthe impact characteristics of aluminium-lithium alloy in China.In this paper, the authors employ split Hopkinson pressure bar technique to do impact testing ofChinese 8090 (nearly the same as ASTM 8090) aluminium-lithium alloy. The specimens are loadedunder impact loading in which the strain rates arc about 103/s and quasi-static loading in which thestrain rates are about 10-3/ s. For comparison,...

The authors arc quite certain that there do not exist previously published experimental data onthe impact characteristics of aluminium-lithium alloy in China.In this paper, the authors employ split Hopkinson pressure bar technique to do impact testing ofChinese 8090 (nearly the same as ASTM 8090) aluminium-lithium alloy. The specimens are loadedunder impact loading in which the strain rates arc about 103/s and quasi-static loading in which thestrain rates are about 10-3/ s. For comparison, the testing of Chinese LY12 (nearly the same asASTM 7075) aluminium alloy arc also done. The stress and strain curves for both materials areshown in Fig.5. It can be seen that the stress-strain curve is always higher under impact loading thanunder quasi-static loading.The increase is greater for Chinese 8090 than for Chinese LY12. In otherwords, Chinese 8090 is more sensitive to strain rate than Chinese LY12. The results also show thatthe Chinese 8090 can withstand higher loading than Chinese LY12 under both impact andquasi-static loading over tested deformation.

The prediction of geometric features of surface crack fatigue growth andfracture growth is one of important projects in the;Leak-Before-Break assessment methodology.In this paper,the law of surface crack fracture growthunder quasi-static loading is experimentally studied with the multiple-specimenmethod.The testing procedure and tested results are presented.