Papers by Keyword: Ultimate Stress

Abstract: Plastics is very important in our lives; they used in all sectors from the high-performance industry to the mass-market industry. In this article, we will interest on the thermoplastic Acrylonitrile Butadiene Styrene (ABS) polymer; this choice is justified by the compatibility of ABS with a wide range of materials. The aim of this work is to evaluate the damage and the reliability of ABS for predict its residual lifetime.To do this, we used notched specimens of ABS prepared according to the ASTM standard, these last one are subject to tensile test at different ray of notch, The experimental results obtained have allowed us to follow the evolution the ultimate stress and then to calculate the damage. Thereafter, it was possible to identify three stages of damage that can predict at first initiation of the damage and the critical damage. Therefore, be able to intervene in time for predictive maintenance. This study also includes a correlation between two methods of calculating the damage namely static damage and damage by unified theory and this by analogy to cyclical behavior. The comparison showed good agreement.

Abstract: According to the microstructures of small grain shellproof ceramic composite, the effective self-consistent method is used to determine the effective stress field of the shellproof ceramic composite. Based on the effective stress field and fracture feature of small grain shellproof ceramic composite, considering the mechanism of growth and coalescence of microvoids, crack nucleation model of the shellproof ceramic composite is built. Under the effect of shearing stress, dislocations slip along slip plane and pile up in matrix grain boundary. Owing to the stress concentration before leading dislocation, there is a stress field around the stress concentration. Letting the maximum tensile stress equal to the theoretic fracture strength of composite matrix, the ultimate stress of small grain shellproof ceramic composite is obtained.

Abstract: Axial compression experiments of eighteen concrete-filled GFRP tube (CFFT) and concrete-filled GFRP reinforced steel tube (CFFST) specimens in total have been carried out to study their mechanical behaviors. Experimental results show that, GFRP tubes with different filament-wound angles could enhance the strength and ductility of core concrete at different levels. Fibers with hoop directions provide the best confinement and enhance the ultimate strength up to 266% comparing with unconfined concrete columns. Fibers with ±45° winding angles have minor effects on bearing capacity, but greatly improve the ductility of concrete columns. Compared with CFST columns, GFRP reinforced CFST columns with hoop direction fibers increase the bearing capacity of 35.0%, and the fibers along 45° winding angles could enhance by 17.5%. The mechanical behavior and the failure modes of the six experimental group specimens are also discussed in this paper.

Abstract: Bone mechanical function is given as a result of the material and structural parameters of bone tissue. We previously reported that the material parameter of regenerated bone can be evaluated dominantly using two indices of the density and the preferred orientation degree of biological apatite (BAp). In addition, bone morphology remarkably changes during bone regeneration, which may lead to a dynamic change in the mechanical function of whole bone. In this study, therefore, material and structural parameters of regenerated bone are analyzed separately. A 5-mm-long defect was introduced in rabbit ulna and spontaneously regenerated, and then a three-point bending test was conducted at the regenerated portion. The important parameter which dominantly controls the whole bone mechanical function shifts from a structural to material parameter during bone regeneration. Moreover, it was statistically demonstrated that the increase in the material parameter is strongly determined by recovery of the orientation degree of the BAp c-axis.