Papers by Author: Sheng Wu Wang

Paper TitlePage

Authors: Huai Rui Zhao, Qiang Li, Sheng Wu Wang
Abstract: A method for combining the FEA softwares, I-DEAS and MSC.Marc, with the iSIGHT design platform is presented to optimize die –pressing (DP) process. In the optimization design, two kinds of optimization algorithms, genetic algorithm (GA) and sequential quadratic programming (SQP), are employed. The result reveals that the residual stress is minimum under conditions that die rake angel equals to 48.50, dieing depth1.9, and friction factor 0.065. The above results give preference to design dieing form tools and process parameters.
2576
Authors: Sheng Wu Wang, Hisatoshi Hirai, Tatsuo Tabaru, A. Kitahara, Hideto Ueno
Abstract: Nb base in-situ composites with the base composition of Nb-5Mo-2W-18Si were prepared by conventional arc-melting and induction heating floating zone melting followed by directional solidification. To investigate the effect of HfC addition, Nb was replaced with 0, 1 and 2 mol% HfC. The in-situ composites predominantly have an eutectic microstructure consisting of Nb solid solution (NbSS) and (Nb,Mo,W))5Si3 (5-3 silicide). The strength at 1470 K and 1670 K increases without fracture toughness decreasing, with increasing the HfC content. Directional solidification also improves the strength at the high temperature. The slip band under the shearing stress occurs in the NbSS during plastic deformation, which contributes to suppress microcrack propagation. It seems that HfC addition reinforces the bonding strength at grain boundary or NbSS/5-3 silicide interface.
1439
Authors: Ai Ling Wen, Rui Ming Ren, Sheng Wu Wang, Jun Yong Yang
Abstract: The enhancement of the fatigue strength is significant for the engineering applications of commercial pure titanium and its alloys. The paper investigated improvement of fatigue strength for commercial pure titanium by combined high-energy shot peening. Firstly, nano-crystallization in surface layer of pure titanium was carried out by high-energy shot peening, and then the shot peening with small diameter shots was introduced to degrade the surface roughness, enhancing the quality of the nano-grained surface. The fatigue limit of pure titanium by high-energy shot peening turns out to be increased by 34%, and the fatigue limit of pure titanium by compound high-energy shot peening turns out to be increased by 52.3%, according to the results. Effective factors such as surface states etc. to fatigue life, the fatigue crack initiation and propagation behaviors were also discussed in this paper.
545
Authors: Ai Ling Wen, R.M. Ren, Sheng Wu Wang, Shinichi Nishida
Abstract: The paper investigated nano-crystallization on surface layer of commercial pure titanium by using high-energy shot peening. The grain size and the microstructure in deformed surface layer by high-energy shot peening are analyzed with X-ray diffraction and TEM etc. In addition, the variations of surface microhardness are examined after high-energy shot peening. The results described that the nano-crystalline surface layer have been formed in commercial pure titanium with a structure of hexagonal closet packet, by high-energy shot peening. The surface microhardness increases and the grain size in nano-crystalline surface layer diminishes, with increasing the time in high-energy shot peening. The minimum nano-crystalline grain size is approximately 40 nm.
1605
Authors: Sheng Wu Wang, Tatsuo Tabaru, Hisatoshi Hirai, Hideto Ueno
Abstract: Nb-base in-situ composites with the base composition of Nb-18Si-2HfC were prepared by conventional arc-melting. Their microstructures and mechanical properties, such as high-temperature strength and room temperature fracture toughness, were investigated to elucidate the effects of Re alloying. The in-situ composites predominantly have eutectic microstructures consisting of an Nb solid solution (NbSS) and Nb5Si3. The compressive strength increased with the increasing Re contents at 1470K and not at 1670 K. The strengthening effect observed at 1470 K is higher than that by W and Mo. Re alloying of about 2 % is valuable for improving both the high temperature strength and room temperature fracture toughness of Nb-18Si-2HfC base materials.
941
Authors: Sheng Wu Wang, Ai Ling Wen, Shinichi Nishida, Nobusuke Hattori
Abstract: Nearly 90% of failures of machines and mechanical parts are caused at the area of stress concentrated in the structural components [1]. Hence, it is important to investigate the method of improving fatigue strength for notched parts, and method of evaluation the fatigue strength of notched parts for mechanical engineering. In this paper, the tests were carried out for improving the fatigue strength of specimens, with the hole notches that have been chamfered by die-pressing. The fatigue strength of notched part is enhanced to around 100% by die-pressing, comparing with notched specimen without die-pressing. Based on the above results, the new method for evaluation the fatigue strength with both the effects of work hardening and residual stress caused by the cold working. The estimated results by the method revealed good agreement with the tested results.
145
Authors: Sheng Wu Wang, Ai Ling Wen, Shinichi Nishida, Wei Da Wang
Abstract: The rotating bending fatigue tests have been carried out to investigate the fatigue limit of specimen with double-notch which is constructed by the step and the blind hole, and the effect of stress concentrations at the double-notched bottoms on the fatigue limits are analyzed using three-dimensional elastic finite element method (3D-EFEM). There are fatigue limits of 17 groups on the single-notched specimen and double-notched specimen obtained in the fatigue tests. The stress field interactions are discussed between the stress field by the blind hole notch and the stress field by step using 3D-EFEM. The results obtained in this study are as follows: The fatigue limit of the double-notch specimen is insensitive to the distance between the blind hole and step for the low carbon structure steel with better ductility; while, for the high-strength steel, superposition and intensification of the stress concentration by the blind hole and step mutually may be avoided, and their adverse effects on the fatigue strength may be become to minimal, when taken appropriate distance between the blind hole and step. The results are significant for engineering design of the multi-notched parts, and studying fatigue strength theory.
965
Authors: Min Liu, Sheng Wu Wang, Jian Zhang, Li Qiong An, Li Dong Chen
Abstract: Y2.85Er0.15Al5O3 was prepared by combustion process. Phase evolution of the synthesized powders was determined by XRD. Single-phase cubic YAG: Er3+ crystalline powders were obtained by calcining the combusted product at 1000°C and no intermidiate phase was observed. SEM morphology showed that the resultant YAG: Er3+ powders were porous. Upconversion emission spectra were measured on the powder compact pumped by a 980nm continuous wave diode laser. The relationship between pump power and luminescence intensity suggested that a two-photon process is active in this sample. The upconversion machanism of YAG: Er3+ system was also discussed.
517
Authors: Sheng Wu Wang, Shu Juan Sun, Ai Ling Wen, Wei Da Wang, Shinichi Nishida
Abstract: The fatigue limit of parts and components that have the multi-notches is important data for the design and manufacture of machinery and traffic equipment which are operated under the high speed or pressure. In this paper the rotating bending fatigue tests have been carried out to investigate the fatigue limit of specimen with double-notch that is constructed of step and blind hole, and analyzed the effect of stress concentrations at the double-notched bottoms on the fatigue limits, using three-dimensional elastic finite element method. Firstly, the fatigue tests of 8 group specimens have been performed for examining the of fatigue limits of the single-notched specimen and double-notched specimen, respectively. Additionally, the stress field interactions between two stress fields by the blind hole notch and step are discussed using three-dimensional elastic finite element method. The main results obtained in this study are as follows: The fatigue limit of the double-notched specimen are down comparison with the fatigue limit of the single-notched specimen; the fatigue limit of the double-notch specimen is insensitive to distance between the blind hole and step for the low carbon structure steel with better ductility; for the high-strength steel, superposition and intensification of the stress concentration by the blind hole and step mutually may be avoided so that their adverse effects on the fatigue strength may be become to minimize, as take appropriate distance between the blind hole and step. The results are significant for the design of engineering design of the multi-notched parts, and the study of fatigue strength.
849
Authors: Sheng Wu Wang, Wei Da Wang, Dian Mai Zhou
Abstract: The main factor of rubber fatigue was stress field. But the way is not sensitive in many cases. To clarify which factors were the main for predict the locations of fatigue crack, we analyzed the factors of stress field and strain field of rubber joint, and relations between the factors and the locations of fatigue crack, using 3D FE simulation. The result showed stress concentration was not sensitive to predict the locations of fatigue crack. The locations are close to strain concentration of rubber joint. In this paper we propose the approach of using strain concentration to predict the fatigue crack locations for rubber joint. This result is significant for the rubber joint design and the study of fatigue strength theoretic.
1505
Showing 1 to 10 of 12 Paper Titles