Combined Tension Bending Research Articles

Elasto-plastic bending behavior of Ti–6Al–4V alloy under coupling conditions of elevated temperature and combined tension-bending

Overload failure under coupling conditions of elevated temperature and combined tension-bending (CTB) is one of the typical failure modes of aero-engine low-pressure compressor blade materials, which is commonly occurring in fighter engines performing low-altitude high-speed penetration missions. In this study, the elasto-plastic deformation behavior and fracture mechanism of Ti–6Al–4V titanium alloy under coupling conditions of elevated temperature and CTB were investigated by experiments and finite element analysis (FEA). CTB tests were conducted on Ti–6Al–4V alloy in the pre-tension ratio range of 0.60–0.90 and in the temperature range of 298 K–573 K. The results show that the maximum bending load, effective bending modulus, and total energy dissipated for the Ti–6Al–4V alloy at room temperature increase with the increase of the pre-tension ratio. The maximum bending load and the energy dissipated are significantly higher at elevated temperatures compared to that of room temperature, due to the elevated temperature induced deformation mode change from bending-dominated to tensile-dominated. The FEA results are in good agreement with the experimental results. SEM fractography indicated that the Ti–6Al–4V alloy fracture at elevated temperature showed only equiaxed dimples, which exhibited a tensile fracture mode. This study is valuable for the in-depth understanding of the deformation behavior and fracture mechanism of blade materials under elevated temperature and complex loads.

Finite Element Modeling for Steel Cord Analysis in Radial Tires

ABSTRACT: This article focuses on steel cord deformation and force investigation within heavy-duty radial tires. Typical bending deformation and tension force distributions of steel reinforcement within a truck bus radial (TBR) tire have been obtained, and they provide useful input for the local scale modeling of the steel cord. The three-dimensional carpet plots of the cord force distribution within a TBR tire are presented. The carcass-bending curvature is derived from the deformation of the carcass center line. A high-efficiency modeling approach for layered multistrand cord structures has been developed that uses cord design variables such as lay angle, lay length, and radius of the strand center line as input. Several types of steel cord have been modeled using the developed method as an example. The pure tension for two cords and the combined tension bending under various loading conditions relevant to tire deformation have been simulated by a finite element analysis (FEA). Good agreement has been found between experimental and FEA-determined tension force-displacement curves, and the characteristic structural and plastic deformation phases have been revealed by the FE simulation. Furthermore, some interesting local stress and deformation patterns under combined tension and bending are found that have not been previously reported. In addition, an experimental cord force measurement approach is included in this article.