Applied Mechanics and Materials Vol. 620

Abstract: In the study, the strengthening effect of aluminium foam in thin-walled aluminium tubes subject to bending load in investigated experimentally and numerically. Bending tests are conducted on foam filler, hollow tube and foam-filled tube. The finite element method is used as well to get deeper insight into the crush failure modes via focusing on the influence from wall thickness of the tube. The obtained information is useful to optimally design foam-filled tubes as energy absorbing devices in automotive engineering. The optimisation results can be implemented to find an optimum foam-filled tube that absorbs the same energy as the optimal hollow tube but with much less weight.

Abstract: Understand the impact of new materials on the study of modern sculpture, stainless steel sculpture and its understanding, awareness and stainless steel sculpture to the current problems that exist through observation, induction and summary, stainless steel sculpture by recognizing the problems at the same time, given a reasonable solution. Such as the use of welding techniques, and how to be colored stainless steel polishing process.

Abstract: A single-ball RCF testing machine was used in order to investigate crack initiation of SUJ2 material at early stage of fatigue. This machine enables observation of a full cross section by sectioning the specimen only once. The RCF tests were carried out under a Hertzian stress of 5.3 GPa, at 3000 rpm. All of the cracks initiated from non-metallic inclusions on 300 mm² sized area were counted, and the relation between the number of cracks and their initiation depths was drawn. Furthermore subsurface shear stress distribution was calculated. Empirical data of the crack distributions and subsurface stress distribution was compared. It was found that the crack starts growing during 3.3×10⁴ - 1.0×10⁵ cycles by the subsurface shear stress.

Abstract: A failure analysis of a single-lap single-bolt composite joint with a countersunk fastener was carried out using a progressive damage model. The FE model considering the distributions of fine and coarse meshes, appropriate contact pairs and the bolt preload was established. Based on the analysis, the five stages in the load-displacement curve and the changes of tilt angle were discussed in detail as well as failure contours of hole laminates at typical events during the damage propagation are illustrated. The inherent development tendency of the tilt angle accompanying with the damage propagation in the single-lap joint vividly depict its failure process.

Abstract: The failure of an adhesive-bonded and bolted composite joint under axial tensile loading is investigated. A progressive damage model consisting of a three dimensional FEM accompanying with a three dimensional maximum stress failure criterion and corresponding material degradation model is established to predict the failure behavior of the joint. The predicted failure load and load-displacement curve are validated by the experimental results is obtained. Moreover, the result shows that the discontinuity between two L-shaped laminates is the weak spot and required to be strengthened.

Abstract: This article uses the finite element method for a particular steel - concrete composite box girder structures were linear buckling analysis and design optimization of web longitudinal stiffeners. By exploring the effects of longitudinal stiffeners geometry and bending stiffness of the composite box girder stability, drawn steel - concrete composite box girder factor of stability of this structure plays a key role. Meanwhile, the optimization of web stiffeners, stiffeners come to a reasonable arrangement for improving the overall stability of the structure, excellent performance play materials and construction economy plays an important role for the stability of the bridge structure similar to the design of future work provide a reference point.

Abstract: Aspect ratio is a key factor to calculate stress intensity factor (SIF) K using fracture mechanics. Cracks are approximated to be semi-circle or semi-ellipse in simple calculation, however, their empirical shapes are changed by stress concentration. In this study, in order to calculate K simply and precisely, a new method to predict fatigue crack initiation stress, σ_w1 of austenitic stainless steel with modified aspect ratio is discussed. The new method succeeded to predict σ_w1 within 20% error from empirical values using average austenite grain sizes.

Abstract: Martensitic high-carbon high-strength SUJ2 bearing steel has been widely used as a main alloy for rolling contact applications, and also in components under bending and tension-compression. In order to enhance the material’s strength, refining the prior austenite grain size through repeated-heating was investigated in our previous work. In this work, we observed the microstructure of twice quenched N-rich SUJ2 steel and performed their rotating bending fatigue tests. It was found that most of cracks on the fracture surface originated from Al₂O₃ inclusions.

Abstract: A new kind of humic acid acetamide compoud was synthesized by chemical modification of humic acid with octadecylamine, and the effect of humic acid acetamide on the rheological properties of oil-based drilling fluids was investigated. The results indicated that the humic acid acetamide had excellent dispersing property, and good capacity of depressing fluid loss. Moreover, the humic acid acetamide had better property of depressing fluid loss than oxidated asphalt. As a result, this humic acid acetamide is an excellent fluid loss agent for diesel oil-based drilling fluids, and is an good alternative to oxidated asphalt.

Abstract: Stainless steel materials (FeCr and FeCrNi-based alloys) are employed in a wide range of modern applications due to their ability to withstand corrosive environments while maintaining good mechanical properties. Their corrosion resistance originates from Cr-rich oxide layer which serves as a barrier against ion diffusion between the alloy and the ambient phase. Custom steel grades can be designed for specific applications by optimizing their properties throughout alloy composition [1].