Haihua Wu, Junfeng Li, Zhengying Wei and Pei Wei
To fabricate a selective laser melting (SLM)-processed AlSi10Mg part with almost full density and free of any apparent pores, this study aims to investigate the effect of ambient…
Abstract
Purpose
To fabricate a selective laser melting (SLM)-processed AlSi10Mg part with almost full density and free of any apparent pores, this study aims to investigate the effect of ambient argon pressure and laser scanning speed on the particles splash during the AlSi10Mg powder bed laser melting.
Design/methodology/approach
Based on the discrete element method (DEM), a 3D model of random distribution of powder particles was established, and the 3D free surface of SLM forming process was dynamically tracked by the volume of fluid, where a Gaussian laser beam acts as the energy source melting the powder bed. Through the numerical simulation and process experimental research, the effect of the applied laser power and scanning speed on the operating laser melting temperature was studied.
Findings
The process stability has a fundamental role in the porosity formation, which is process-dependent. The effect of the processing conditions on the process stability and the resultant forming defects were clarified.
Research limitations/implications
The results shows that the pores were the main defects present in the SLM-processed AlSi10Mg sample, which decreases the densification level of the sample.
Practical implications
The optimal processing parameters (argon pressure of 1,000 Pa, laser power of 180 W, scan speed of 1,000 mm/s, powder layer thickness of 35 µm and hatch spacing of 50 µm ) applied during laser melting can improve the quality of selective laser melting of AlSi10Mg,
Social implications
It can provide a technological support for 3D printing.
Originality/value
Based on the analysis of the pore and balling formation mechanisms, the optimal processing parameters have been obtained, which were argon pressure of 1,000 Pa, laser power of 180 W, scan speed of 1,000 mm/s, powder layer thickness of 35 µm and hatch spacing of 50 µm. Then, a near-fully dense sample free of any apparent pores on the cross-sectional microstructure was produced by SLM, wherein the relative density of the as-built samples is larger than 97.5%.
Details
Keywords
Kun Sun, Dichen Li, Haihua Wu, Minjie Wang and Xiaoyong Tian
The purpose of this paper is to bring up the concept of multi‐material electromagnetic band‐gap structure (EBGs) and develop a method for its fabrication. Meanwhile, its microwave…
Abstract
Purpose
The purpose of this paper is to bring up the concept of multi‐material electromagnetic band‐gap structure (EBGs) and develop a method for its fabrication. Meanwhile, its microwave properties were studied and compared with the traditional EBGs consisting of two kinds of material.
Design/methodology/approach
Stereolithography (SL) and gel casting were used to fabricate 3D multi‐material EBGs. Resin mold was designed and fabricated based on SL process, slurries loaded with 55vol per cent Al2O3 and 55vol per cent TiO2, respectively, were prepared, and using gel casting, multilayer EBGs with diamond structure were fabricated. T/R method was used to obtain the characteristic parameter S21 of the EBGs; meanwhile, characters of their band structure were studied based on plane wave expansion method.
Findings
The fabricated EBGs with a TiO2‐resin‐air structure showed a band gap from 11.7 GHz to 16.0 GHz along <1, 1, 0> direction; the EBGs with a TiO2‐resin‐Al2O3 structure showed a band gap from 11.4 GHz to 11.9 GHz along <1, 1, 0> direction. Both of them agreed well with the simulation result. Also, through the study of multi‐material EBGs' microwave properties, it could be seen that this structure was a good approach to adjust the band gap.
Originality/value
With the concept of multi‐material EBG structure brought up, multilayer 3D EBGs were designed and fabricated based on SL combined with gel casting. It could be seen that multi‐material EBGs was a good approach to adjust the band gap. Also, the fact that the testing result matched the simulation validates the feasibility of the process.
Details
Keywords
Haihua Wu, Dichen Li and Nannan Guo
The purpose of this paper is to develop a novel process of integral ceramic molds for investment casting of hollow turbine blades.
Abstract
Purpose
The purpose of this paper is to develop a novel process of integral ceramic molds for investment casting of hollow turbine blades.
Design/methodology/approach
At first, a resin pattern of a hollow turbine blade prototype is fabricated by stereolithography (SL). And then aqueous gelcasting process is utilized to fill the resin pattern with ceramic slurry of low viscosity and low shrinkage, through in situ polymerization of the slurry a ceramic mold is formed. At last, the ceramic mold for investment casting of hollow turbine blade is obtained by vacuum drying, pyrolyzing and sintering.
Findings
An integral ceramic mold is successfully fabricated by combining SL and gelcasting process, cores and shell are connected with each other and thus high relative position accuracy is guaranteed. Properties of integral ceramic mold at room temperature and high temperature satisfy the requirements of directional casting for complex‐shaped thin‐walled blades.
Research limitations/implications
Because the integral ceramic mold is a close body, it is very difficult to directly measure its inner dimensions and the relative position accuracy of cores and shell, and the further research is needed.
Originality/value
This method enhanced the versatility of using SL prototype in the fabrication of integral ceramic mold for investment castings. Although this paper took a hollow turbine blade as an example, this method is also capable of fabricating integral ceramic molds for other complex investment castings.
Details
Keywords
Zhongyi Wang, Haihua Chen, Chengzhi Zhang, Wei Lu and Jian Wu
Wen Wu, Haihua (Jason) Wang and Lu Lu
The purpose of this paper is to fill important gaps by using the belongingness theory and examining the effects of individual-level workplace ostracism on members’ voice behavior…
Abstract
Purpose
The purpose of this paper is to fill important gaps by using the belongingness theory and examining the effects of individual-level workplace ostracism on members’ voice behavior and the effects of group-level workplace ostracism.
Design/methodology/approach
The authors used samples of 77 groups from a high-technological company.
Findings
Individual-level workplace ostracism is detrimental to group members’ promotive and prohibitive voice behavior, and group members’ belongingness mediates such effect; and group-level workplace ostracism is negatively related to group cohesion. The influence of group members’ perception of ostracism on their voice behavior is contingent on overall level of ostracism.
Originality/value
Despite of a growing body of studies on workplace ostracism “the extent to which an individual perceives that he or she is ignored or excluded by others at workplace”, the effects of workplace ostracism on individual’s voice behavior in group settings have received scant attention.
Details
Keywords
Mengying Wu, Rongsong Wang, Haihua Wang and Christophe Estay
The purpose of this paper is to examine the effect of psychological contract breach on destructive by developing a moderated mediation model. The model focuses on the mediating…
Abstract
Purpose
The purpose of this paper is to examine the effect of psychological contract breach on destructive by developing a moderated mediation model. The model focuses on the mediating role of moral identity and moral disengagement and the moderating role of moral belief.
Design/methodology/approach
This study conducted a three-wave questionnaire survey and used 377 matched-sample data to test the hypotheses. PROCESS bootstrapping program in SPSS and confirmatory factor analysis in AMOS software were adopted in this study.
Findings
Results reveal that psychological contract breach has a positive effect on destructive leadership behavior, and the relationship is mediated by moral identity and moral disengagement; moral belief not only moderates the relationship between psychological contract breach and destructive leadership behavior, but also moderates the mediation effect of moral identity and moral disengagement.
Originality/value
First, this study enriches the destructive leadership behavior literature by verifying psychological contract breach as an antecedent. Second, this study discusses the role of morality in the formation mechanism of destructive leadership behavior by testing the mediating effect of moral identity and moral disengagement and the moderating effect of moral belief.
Details
Keywords
Zhongyi Wang, Xueyao Qiao, Jing Chen, Lina Li, Haoxuan Zhang, Junhua Ding and Haihua Chen
This study aims to establish a reliable index to identify interdisciplinary breakthrough innovation effectively. We constructed a new index, the DDiv index, for this purpose.
Abstract
Purpose
This study aims to establish a reliable index to identify interdisciplinary breakthrough innovation effectively. We constructed a new index, the DDiv index, for this purpose.
Design/methodology/approach
The DDiv index incorporates the degree of interdisciplinarity in the breakthrough index. To validate the index, a data set combining the publication records and citations of Nobel Prize laureates was divided into experimental and control groups. The validation methods included sensitivity analysis, correlation analysis and effectiveness analysis.
Findings
The sensitivity analysis demonstrated the DDiv index’s ability to differentiate interdisciplinary breakthrough papers from various categories of papers. This index not only retains the strengths of the existing index in identifying breakthrough innovation but also captures interdisciplinary characteristics. The correlation analysis revealed a significant correlation (correlation coefficient = 0.555) between the interdisciplinary attributes of scientific research and the occurrence of breakthrough innovation. The effectiveness analysis showed that the DDiv index reached the highest prediction accuracy of 0.8. Furthermore, the DDiv index outperforms the traditional DI index in terms of accuracy when it comes to identifying interdisciplinary breakthrough innovation.
Originality/value
This study proposed a practical and effective index that combines interdisciplinary and disruptive dimensions for detecting interdisciplinary breakthrough innovation. The identification and measurement of interdisciplinary breakthrough innovation play a crucial role in facilitating the integration of multidisciplinary knowledge, thereby accelerating the scientific breakthrough process.
Details
Keywords
Haihua Wang, Shujie Li, Yanyan Gong and Ying Wang
This study aims to investigate the impact of corporate social responsibility (CSR) on green innovation by considering the three dimensions of green innovation cognition, behavior…
Abstract
Purpose
This study aims to investigate the impact of corporate social responsibility (CSR) on green innovation by considering the three dimensions of green innovation cognition, behavior and outcomes and to explore the role of situational and measurement factors in this relationship.
Design/methodology/approach
This study adopts a meta-analysis method to integrate 208,997 observations from 48 independent empirical studies on CSR and green innovation.
Findings
CSR positively affects green innovation cognition, behavior and outcomes. Additionally, the relationship between CSR and green innovation is stronger in Western cultural background than in Eastern ones. The impact of CSR on green innovation is also more significant in small and medium-sized enterprises (SMEs). Moreover, this study shows that the correlation between CSR and green innovation is stronger when the source of data is primary data and when green innovation is measured by non-patent methodologies.
Originality/value
This study elucidates the impact of CSR on green innovation and further clarifies the potential reasons for the divergent findings in existing related studies. The article enriches the theoretical results related to CSR and green innovation and provides valuable insights and references for corporate decision-makers.
Details
Keywords
Yi Zhang, Haihua Zhu and Dunbing Tang
With the continuous upgrading of the production mode of the manufacturing system, the characteristics of multi-variety, small batch and mixed fluidization are presented, and the…
Abstract
Purpose
With the continuous upgrading of the production mode of the manufacturing system, the characteristics of multi-variety, small batch and mixed fluidization are presented, and the production environment becomes more and more complex. To improve the efficiency of solving multi-objective flexible job shop scheduling problem (FJSP), an improved hybrid particle swarm optimization algorithm (IH-PSO) is proposed.
Design/methodology/approach
After reviewing literatures on FJSP, an IH-PSO algorithm for solving FJSP is developed. First, IH-PSO algorithm draws on the crossover and mutation operations of genetic algorithm (GA) algorithm and proposes a new method for updating particles, which makes the offspring particles inherit the superior characteristics of the parent particles. Second, based on the improved simulated annealing (SA) algorithm, the method of updating the individual best particles expands the search scope of the domain and solves the problem of being easily trapped in local optimum. Finally, analytic hierarchy process (AHP) is used in this paper to solve the optimal solution satisfying multi-objective optimization.
Findings
Through the benchmark experiment and the production example experiment, it is verified that the proposed algorithm has the advantages of high quality of solution and fast speed of convergence.
Research limitations/implications
This method does not consider the unforeseen events that occur during the process of scheduling and cause the disruption of normal production scheduling activities, such as machine breakdown.
Practical implications
IH-PSO algorithm combines PSO algorithm with GA and SA algorithms. This algorithm retains the advantage of fast convergence speed of traditional PSO algorithm and has the characteristic of inheriting excellent genes. In addition, the improved SA algorithm is used to solve the problem of falling into local optimum.
Social implications
This research provides an efficient scheduling method for solving the FJSP problem.
Originality/value
This research proposes an IH-PSO algorithm to solve the FJSP more efficiently and meet the needs of multi-objective optimization.