查看更多>>摘要：The present article describes experimental research on the impact resistance of protective rubber panels. The investigation was carried out with three different types of panels made of a rubber granulate, with polypropylene glue as the binder. Thus, all three types of rubber panels were subjected to a determination and analyses of their Shore hardness. The third type of tested rubber panel was found to exhibit a higher hardness due to the higher content of glue. It was observed that the novel double-layer protective rubber panel with a higher content of glue and a lower content of granulate was able to absorb, without any visible damage, approximately 6.5-times more impact energy than the single-layer rubber panel with a higher content of granulate and a lower content of glue.
查看更多>>摘要：Weld joints necessary for various structures are heterogeneous and anisotropic which are known to be high-risk due to inevitable defects. The location dependence of material properties in the weld joint means Linear Elastic Fracture Mechanics (LEFM) limited to homogeneous and isotropic materials may not be appropriate. In this paper, the weld metal of Q235 steel butt weld joint was taken as an object, and Boundary Effect Model (BEM) was introduced to deduce the fracture toughness KIC of weld metal from the yield load Py, which bypassed the stringent LEFM requirements on material homogeneity, specimen size, and initial crack/notch length. 68 threepoint bending (3-p-b) specimens with different initial notches were tested, and consistent fracture toughness KIC and yield strength sigma y of the weld metal were determined through curve-fitting based on BEM. Furthermore, these results were verified via specification-compliant tensile and Charpy impact tests respectively, demonstrating that the boundary effect model can be applied to determine the location-dependent material properties in welded sections of steel structures.
查看更多>>摘要：Solar receivers are an integral part of a concentrated solar power plant and commonly utilise tubular structures to absorb solar energy and transfer the heat into a heat transfer fluid. These systems often contain dissimilar materials joined through welds which are exposed to cyclic temperatures, which can be a locus of failure. A systematic forensic analysis was carried out on a low-pressure CO2 receiver that had developed extensive cracking. Microstructural characterisation using micro-computed tomography was performed to understand the failure mechanism in an area adjacent to a welded section of the two dissimilar alloys Haynes 230 and 253 MA. An electrolytical oxalic acid etch showed grain boundary damage from oxidation. Grain boundary damage through oxidation was confirmed with SEM and energy dispersive X-ray spectroscopy (EDX) analysis as the likely metallurgical degradation mechanism which, combined with thermally induced stress cycles led to the failure of the weaker stainless-steel tube adjacent to the weld.
查看更多>>摘要：A systematic investigation on gear scuffing capacity under oil jet lubrication was presented numerically and experimentally. A sequence coupling numerical methodology was proposed for the effective establishment of the gear temperature model. A gear scuffing test under jet lubrication was designed and conducted, in which the gear temperature was measured via a developed wireless measuring system. The proposed testing method enables a quick evaluation of gear scuffing failure without frequently dismantling the gearbox. The simulated gear bulk temperature is compared with experimental results and shows consistency, the largest deviation between which during the whole gear scuffing test is 5.4%. The simulation model provides an efficient and reliable method for the evaluation of gear scuffing capacity.
查看更多>>摘要：The purpose of this study is to investigate the size effect on reinforcement concrete (RC) shear walls having different shear span ratios and vertical reinforcement ratios by the two-dimensional (2D) meso-scale simulation method. Firstly, the meso-scale simulation method was verified by the existing test data. Then, the effects of shear span ratio and vertical reinforcement ratio on the mechanical properties of RC shear walls with different structure sizes were studied by using this method. The results show that: 1) The failure mode of shear walls changes from shear failure to bending failure with the increase of the shear span ratio. 2) With the increase of the shear span ratio, the shear capacity of the shear wall decreases and the ductility increases, which leads to the weakening of the size effect. 3) The increase of the vertical reinforcement ratio has a slight increase in the shear capacity of the shear wall, but has almost no effect on the ductility and size effect. In addition, based on the established size effect law which can reflect the quantitative effect of horizontal reinforcement ratio and axial compression ratio, a new size effect law for RC shear wall was proposed considering the quantitative effect of shear span ratio.
NSTL
Elsevier