Papers by Author: Bao Zong Huang

Abstract: Aiming at Pbfree solder Sn4.0Ag0.5Cu (in short, SAC405), the uniaxial tensile tests are accomplished with constant strain-rate under different temperature and strain-rate load conditions. The elastic-viscoplastic behaviors of SAC405 solders are studied. The rate-dependent material main properties are analyzed, such ad yield limit, tensile strength, saturation stress, etc. Partitioned constitutive model is accepted to describe the constitutive behavior of SAC405 solder. The seven parameters in partitioned model are determined by experiment data. The results of numerical simulation are fitted with the experimental values.

Abstract: The postbuckling behavior and progressive failure of thin-walled box-shape composite beams (BSCBs) have been studied using a simplified composite panel model. It is shown that the carrying capacity of BSCBs under bending and torsion mainly depends on the postbuckling and progressive failure of panels. It is often necessary to identify and follow secondary buckling of tailored panels for correct estimation of carrying capacity. The failure process of stiffened composite panels is simulated in following path. The criterion of local failure in flange of stiffeners is applied to predict the ultimate failure of stiffened composite panels and thin-walled BSCBs. The comparison of the modeling and test shows that the prediction of BSCBs failure is satisfactory.

Abstract: A micro-mechanical model and simulation for the damage behavior of short fiber interleaves (SFIs) were developed based on Mori-Tanaka method and an equivalent approach to interface debonding (Fitoussi etc 1990). The damage evolution and the stress-strain relation of SFIs have been predicted in the cases of interlaminar shear, out-of and in-plane tension, respectively. The simulation indicates that the damage always starts from the interface debonding of fibers perpendicular to load and the matrix cracking in the direction parallel to fibers, and then rapidly spreads to more fibers during loading. The strength and the ultimate strain in out-of-plane tension are much lower than that in interlaminar shear and in-pane tension. The strength and failure probability of interface bonding are the most considerable factors to affect the damage and failure of SFIs. The comparison of the simulation with the interlaminar shear test shows a good agreement.

Abstract: A special test setup was designed and used in compression shear test of unidirectional carbon fiber composites to study the effect of short fiber interleaves (SFIs) on the interlaminar shear behavior. The comparative tests for two kinds of double-notched compression specimens, with and without SFIs, were carried out to determine the interlaminar shear strength and modulus (ILSS and ILSM) and to examine the failure characteristics. To determine ILSM of the specimens with SFIs an inversion analysis method was proposed based on comparing compression displacement of specimens with and without SFIs. The experimental results show that SFIs makes ILSS decreasing due to lower interface strength, and the complex damage process of SFIs leads to a considerable increase of interlaminar shear compliance.

Abstract: This paper proposes an improved damage model and derives the shear correction factors for the model based on the Whitney[1] method. As the model is mainly used in the delamination front, the overly strong assumptions for geometric deformation in this region may be relaxed so that more realistic displacement fields can be established.