Analysis, evaluation and interpretation of measured signals become important components in engineering research and practice, especially for material characteristic parameters which can not be obtained directly by experimental measurements. The present paper proposes a hybrid-inverse analysis method for the identification of the nonlinear material parameters of any individual component from the mechanical responses of a global composite. The method couples experimental approach, numerical simulation with inverse search method. The experimental approach is used to provide basic data. Then parameter identification and numerical simulation are utilized to identify elasto-plastic material properties by the experimental data obtained and inverse searching algorithm. A numerical example of a stainless steel clad copper sheet is consid- ered to verify and show the applicability of the proposed hybrid-inverse method. In this example, a set of material parameters in an elasto-plastic constitutive model have been identified by using the obtained experimental data.
Honglei ZhangXuehui LinYanqun WangQian ZhangYilan Kang
We propose a substrate-free focal plane array （FPA） and the microcantilevers extend from a supporting frame. in this paper. The solid substrate is completely removed, Using finite element analysis, the thermal and mechanical characterizations of the substrate-free FPA are presented. Because of the large decrease in thermal conductance, the supporting frame is temperature dependent, which brings out a unique feature： the lower the thermal conductance of the supporting frame is, the higher the energy conversion efficiency in the substrate-free FPA will be. The results from the finite element analyses are consistent with our measurements： two types of substrate-free FPAs with pixel sizes of 200×200 and 60×60 um^2 are implemented in the proposed infrared detector. The noise equivalent temperature difference （NETD） values are experimentally measured to be 520 and 300 mK respectively. Further refinements are considered in various aspects, and the substrate-free FPA with a pixel size of 30×30 um^2 has a potential of achieving an NETD value of 10 mK.
An experimental investigation of the influence of temperature on the Portevin-Le Chatelier(PLC) effect in Al-Mg alloy is conducted.Under a certain strain rate,the PLC effect is present in the temperature range of 223-328 K.The serration amplitude increases monotonically with increasing temperature,whereas the behaviors of the serration period and the critical strain with temperature include a descending branch under corresponding low temperature range and an ascending branch under corresponding high temperature range.The analysis in relation with dynamic strain aging(DSA) indicates that the temperature plays an important role in the PLC effect by dictating the solubility and the diffusibility of solute atoms.Both the concentration and the diffusibility of solute atoms contribute to increasing the serration amplitude.Under the descending branch temperature range,the serration period mainly depends on the preparation phase and the dominant factor of critical strain is the velocity of dislocations.However,under the ascending branch temperature range,the serration period mainly depends on the pinning phase and the dominant factor of critical strain is the applied stress required for unpinning.
FU ShiHuaZHANG QingChuanHU QiGONG MingCAO PengTaoLIU HaoWen
