Xushan Zhao, Yuanxun Wang, Guilan Wang, Runsheng Li and Haiou Zhang
This paper aims to summarize the influence law of hybrid deposited and micro-rolling (HDMR) technology on the shaping strain and residual stress. And the rolling parameters…
Abstract
Purpose
This paper aims to summarize the influence law of hybrid deposited and micro-rolling (HDMR) technology on the shaping strain and residual stress. And the rolling parameters combination was further optimized to guide the actual production.
Design/methodology/approach
This paper proposed a three-dimensional coupled thermo-mechanical model of the HDMR process. The validated model is used to investigate the influences of rolling parameters on stress and plastic strain (the distance between the energy source and roller [De–r], the rolling compression [cr] and the friction coefficient [fr]). The orthogonal optimization of three factors and three levels was carried out. The influence of rolling parameters on the plastic strain and residual stress is analyzed.
Findings
The simulation results show that HDMR technology can effectively increase the shaping strain of the weld bead and reduce the residual tensile stress on the weld bead surface. Furthermore, the influence of rolling parameters on stress and strain is obtained by orthogonal analysis, and the corresponding optimal combination is proposed. Also, the rolling temperature significantly affects the residual stress, and the rolling reduction has a substantial effect on the plastic deformation.
Research limitations/implications
Owing to the choice of research methods, this paper failed to study microstructure evolution.
Originality/value
This paper provides a reference principle for the optimal selection of rolling parameters in HDMR.
Details
Keywords
Rui Wang, Haiou Zhang, Wang Gui-Lan and Xushan Zhao
The wire and arc additive manufacturing (WAAM) is a promising technology, but the parts are mostly manufactured on the plane and along the vertical direction. The purpose of this…
Abstract
Purpose
The wire and arc additive manufacturing (WAAM) is a promising technology, but the parts are mostly manufactured on the plane and along the vertical direction. The purpose of this paper is to propose a cylindrical slicing and manufacturing method.
Design/methodology/approach
For revolved parts, e.g. blades of a propeller, instead of planes, a series of cylindrical surfaces intersect with the STL model of the part. The generated slicing layers lie on the cylindrical surface, and then these spatial contours are unfolded onto the plane by the use of the cylindrical coordinate system. A deposition system based on an NC machine is established to examine deposition paths. The temperature and stress of part of two deposition orders are analyzed using the finite element method.
Findings
The scan parallel path and contour offset path are not suitable to fabricate blades directly. The hybrid of two types of paths and the hybrid of skeleton and contour offset paths are capable of forming blades without gaps. Deposition symmetrically can decrease the deformation of the propeller.
Originality/value
The slicing algorithm is simply implemented and practicable for any parts. The recognition of gaps and supplementary skeleton path can guarantee the full deposition of contour offset paths.
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Xushan Zhao, Yuanxun Wang, Haiou Zhang, Runsheng Li, Xi Chen and Youheng Fu
This paper aims to summarize the influence law of hybrid deposited and micro-rolling (HDMR) technology on the bead morphology and overlapping coefficient. A better bead topology…
Abstract
Purpose
This paper aims to summarize the influence law of hybrid deposited and micro-rolling (HDMR) technology on the bead morphology and overlapping coefficient. A better bead topology positively supports the overlapping deposited in multi-beads between layers while actively assisting the subsequent layer's deposition in the wire and arc additive manufacturing (WAAM). Hybrid-deposited and micro-rolling (HDMR) additive manufacturing (AM) technology can smooth the weld bead for improved surface quality. However, the micro-rolling process will change the weld bead profile fitting curve to affect the overlapping coefficient.
Design/methodology/approach
Weld bead contours for WAAM and HDMR were extracted using line lasers. A comparison of bead profile curves was conducted to determine the influence law of micro-zone rolling on the welding bead contour and fitting curve. Aiming at the optimized overlapping coefficient of weld bead in HDMR AM, the optimal HDMR overlapping coefficient curve was proposed which varies with the reduction based on the best surface flatness. The mathematical model for overlapping in HDMR was checked by comparing the HDMR weld bead contours under different rolling reductions.
Findings
A fitting function of the bead forming by HDMR AM was proposed based on the law of conservation of mass. The change rule of the HDMR weld bead overlapping spacing with the degree of weld bead rolling reduction was generated using the flat-top transition calculation for this model. Considering the damming-up impact of the first bead, the overlapping coefficient was examined for its effect on layer surface flatness.
Originality/value
Using the predicted overlapping model, the optimal overlapping coefficients for different rolling reductions can be achieved without experiments. These conclusions can encourage the development of HDMR technology.
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Shan Xu, Yanling Wang and Jiafei Jin
The main purpose of present study is to investigate how familial collectivism and gender affect the psychological contract violation–turnover intention relationship by comparing…
Abstract
Purpose
The main purpose of present study is to investigate how familial collectivism and gender affect the psychological contract violation–turnover intention relationship by comparing Chinese with American samples.
Design/methodology/approach
In total, 688 and 892 full-time workers were recruited, respectively, from China and the USA to form the two samples. Then, three-way interaction regression models were used to test the hypotheses.
Findings
The results indicate that familial collectivism will negatively moderate the psychological contract violation–turnover intention relationship in the Chinese sample and positively moderate their relationship in the American sample. Moreover, the moderating effect of familial collectivism on the relationship between psychological contract violation and turnover intention is significant among the male employees and insignificant among the female employees for Chinese sample. Whereas for the American sample, the moderating effects are significant among both the male and the female employees.
Originality/value
This study improves the theoretical model of Turnley and Feldman (1999) by examining the moderating effect of familial collectivism and gender differences on the relationship between psychological contract violation and turnover intention. And two samples (China vs the USA) are used in the study, which helps to explain the possible difference in influencing the relationship between psychological contract violation and turnover intention between two nations. The main practical implication for managers is that organizations should recognize the importance of the gender role and individuals’ culture orientation when implementing different human resource management policies.