Xiao Wang

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Organization: Jiangsu University

Department: School of Mechanical Engineering

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Experimental investigation on: Laser shock micro-forming process using the mask and flexible pad

Co-reporter:Xiao Wang, Liyin Li, Zongbao Shen, Chaofei Sha, Shuai Gao, Cong Li, Xianqing Sun, Youjuan Ma, Huixia Liu

Optics and Lasers in Engineering 2017 Volume 88() pp:102-110

Publication Date(Web):January 2017

DOI:10.1016/j.optlaseng.2016.08.003

•The mask and flexible laser shock forming process were investigated.•The mask and the laser beam were employed as the variable convex mold.•The plasticine was used as the flexible support.•The pulse energy, grain size, and the number of the laser pulse were investigated.•Surface quality and thickness distribution of the workpiece were analyzed.A forming process called the mask and flexible pad laser shock forming was proposed to fabricate the micro-features on the copper foil. In this process, the mask and laser beam were used as rigid punches. Shock waves induced by plasma were used as the source of loading and plasticine was used as a flexible pad. This was a micro scale and high strain rate forming process and the traditional forming method with micro-mold was changed. In the experiment, surface morphology of formed parts was represented and it was found that the mask played a significant role in the forming process. In order to understand the forming process in the experiment, process parameters, including laser pulse energy, numbers of laser pulse and grain size, were analyzed. The experimental results showed that different parameters had different effects on formed parts. The surface quality and the thickness distribution of formed parts were investigated. It was found that formed parts could keep good surface quality after laser shocking and the reasons were explored. The thickness distribution was measured and the thickness thinning rate was calculated. There was no local tightening or rupture in the forming area. In this paper, the micro-features could be obtained on metallic foils and the method of mold-free was proved to be feasible.

Investigation on enhancement of weld strength between PMMA and PBT in laser transmission weldingUsing intermediate material

Co-reporter:Xiao Wang;Xuejiao Zhong;Wei Liu;Baoguang Liu ;Huixia Liu

Journal of Applied Polymer Science 2016 Volume 133( Issue 44) pp:

Publication Date(Web):

DOI:10.1002/app.44167

ABSTRACT

Poly(methyl methacrylate) (PMMA) and poly(butylene terephthalate) (PBT) are widely used in industry; however, poor compatibility between two materials lead to poor weld strength. Polycarbonate (PC) has good compatibility with PMMA and PBT. Therefore, the welding method was that PC film as intermediate material was used to enhance weld strength in laser transmission welding (LTW) of PMMA and PBT. Through the LTW experiment, the weld strength was tested by mechanical testing and it was found that the best weld strength was improved more than four times than the weld strength without intermediate material. By observing the micro morphology of the weld zone, one reason was founded that the bubbles can be used to form micro-mechanical riveting to enhance the weld strength. The reptation time for PMMA, PC, and PBT were investigated to analyze the establishment of the weld strength. When the reptation time is much shorter than time in molten state, the higher weld strength is feasible. It can be concluded that the weld strength of PC/PBT was higher than the weld strength of PMMA/PC. The equilibrium interfacial width was calculated through Helfand's theory to analyze the compatibility of dissimilar materials. The equilibrium interfacial width for PMMA/PC and PC/PBT were similar to tube diameter. That is the reason for weld strength enhancement. And then, the response surface methodology was designed to predict the weld strength.© 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44167.

Experimental and numerical investigation of laser shock synchronous welding and forming of Copper/Aluminum

Co-reporter:Xiao Wang, Hongfeng Zhang, Zongbao Shen, Jianwen Li, Qing Qian, Huixia Liu

Optics and Lasers in Engineering 2016 Volume 86() pp:291-302

Publication Date(Web):November 2016

DOI:10.1016/j.optlaseng.2016.06.018

•The laser synchronous welding and forming method can complete welding process and forming process of dissimilar metal materials in a single procedure.•The surface roughness under different laser energy and standoff distances were measured to evaluate the quality of the samples.•The Energy Disperse Spectroscopy was conducted in the welding interface to estimate the states of element diffusion.•The shear stress distribution and effective plastic strain in bonded region and unbonded region were analyzed to predict whether the welding process is took place or not.A novel laser shock synchronous welding and forming method is introduced, which utilizes laser-induced shock waves to accelerate the flyer plate towards the base plate to achieve the joining of dissimilar metals and forming in a specific shape of mold. The samples were obtained with different laser energies and standoff distances. The surface morphology and roughness of the samples were greatly affected by the laser energy and standoff distances. Fittability was investigated to examine the forming accuracy. The results showed that the samples replicate the mold features well. Straight and wavy interfaces with un-bonded regions in the center were observed through metallographic analysis. Moreover, Energy Disperse Spectroscopy analysis was conducted on the welding interface, and the results indicated that a short-distance elemental diffusion emerged in the welding interface. The nanoindentation hardness of the welding regions was measured to evaluate the welding interface. In addition, the Smoothed Particle Hydrodynamics method was employed to simulate the welding and forming process. It was shown that different standoff distances significantly affected the size of the welding regions and interface waveform characteristics. The numerical analysis results indicated that the opposite shear stress direction and effective plastic strain above a certain threshold are essential to successfully obtain welding and forming workpiece.

Micro scale laser shock forming of pure copper and titanium sheet with forming/blanking compound die

Co-reporter:Xiao Wang, Di Zhang, Chunxing Gu, Zongbao Shen, Youjuan Ma, Yuxuan Gu, Tangbiao Qiu, Huixia Liu

Optics and Lasers in Engineering 2015 Volume 67() pp:83-93

Publication Date(Web):April 2015

DOI:10.1016/j.optlaseng.2014.09.019

•A novel micro scale laser shock forming for complex and full parts is presented.•The special die can achieve the forming and blanking at the same time.•Good surface quality can be obtained as no tool marks are created with sot punch.•The mechanical properties of the parts would be improved after impact.A new process fabricating micro parts of thin metal foils by laser shock waves with forming/blanking compound die is reported in this article, in which flexible rubber material was used as the soft punch to act on the thin metal sheet. Systematic studies were carried out experimentally on the process with different laser energies and materials. The formed parts were examined in terms of their morphology, surface roughness, forming depth and mechanical properties (including nanohardness, plasticity and elastic modulus) characterized by nanoindentation test. According to the results, the ablation states of confinement medium and the surface roughness of the different regions change with energies. Additionally, the proper energies are necessary to form complex parts and the forming process can be applied to manufacture parts with good surface quality. What׳s more, the nanoindentation test results showed that the nanohardness, plasticity and elastic modulus of material were increased after impact. The increase in nanohardness and plasticity can attribute to higher stiffness of the parts. The enhanced elastic modulus indicates an increased stiffness of the parts, providing an evidence for the reduced spring back of copper during laser shocking.

Investigation of a combined embossing and blanking process using laser shock wave

Co-reporter:Xiao Wang;Di Zhang;Chunxing Gu;Zongbao Shen

International Journal of Material Forming 2015 Volume 8( Issue 2) pp:317-325

Publication Date(Web):2015 April

DOI:10.1007/s12289-014-1171-1

Laser shock forming is a three-dimensional forming technique. It is promising for achieving precise, well-controlled, low-cost, high efficiency 3D metallic microstructures. In this research, a combined process of embossing and blanking is studied by experimental and simulation methods, in which the embossing and blanking of copper sheets are performed at the same time in only one operation. In order to obtain multi-workpieces in one process, overlapping laser spots were applied in the experiment. Moreover, the influence of laser energies on the work pieces were considered, and the results show that the micro features on the boss surface of the mold were successfully replicated on the blanking copper foil surface with the suitable energy. By evaluating the surface roughness data, it can imply that the work piece surface can fit the mold surface. Meanwhile, the process of the combined embossing and blanking was also studied by numerical simulation, the simulation results show that the finite element analysis can predict the final shape of work piece properly, verifying the feasibility of this process.

Size effects on formability in microscale laser dynamic forming of copper foil

Co-reporter:Xiao Wang, Youjuan Ma, Zongbao Shen, Yuxuan Gu, Di Zhang, Tangbiao Qiu, Huixia Liu

Journal of Materials Processing Technology 2015 220() pp: 173-183

Publication Date(Web):

DOI:10.1016/j.jmatprotec.2015.01.020

Numerical-simulation-driven optimization of a laser transmission welding process under consideration of scattering

Co-reporter:Xiao Wang;Hao Chen ;Huixia Liu

Journal of Applied Polymer Science 2014 Volume 131( Issue 12) pp:

Publication Date(Web):

DOI:10.1002/app.40396

ABSTRACT

In this study, because the use of semicrystalline polypropylene (upper material) leads to the scattering of laser radiation, an integrated method for a numerical-simulation-driven optimization of the laser transmission welding (LTW) process was investigated through the finite element method (FEM), response surface methodology (RSM), and experiments (EX). First, EX for measuring the actual laser power and spot diameter within the weld interface were conducted; these were used to simulate the temperature field and molten pool geometric characteristic parameters of the LTW process. Then, central composite design was used to design the EX, and RSM was used to establish mathematical models. Finally, the desirability function was used to determine the optimal process parameters. The experimental results nearly agreed with the simulated and predicted values. The results illustrate that the integrated (FEM–RSM–EX) approach was an effective optimization method and could play a significant guiding role in LTW EX and in quickly optimizing the process parameters. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40396.

Laser indirect shock micro-embossing of commercially pure copper and titanium sheet

Co-reporter:Xiao Wang, Zongbao Shen, Chunxing Gu, Di Zhang, Yuxuan Gu, Huixia Liu

Optics and Lasers in Engineering 2014 Volume 56() pp:74-82

Publication Date(Web):May 2014

DOI:10.1016/j.optlaseng.2013.12.012

•Laser-driven flyer is used to load the workpiece in micro-embossing.•Strain states are used to interpret the variation in thickness distribution.•Increasing laser energy will increase forming depth if fracture is not detected.•Too high laser energy will induce fracture on 8 μm copper and 13 μm titanium.•With further development, the new technique can realize the blanking forming.Laser indirect shock micro-embossing is a novel micro-high velocity forming technique, which uses laser-driven flyer to load the workpiece. In this paper, laser indirect shock micro-embossing of commercially pure copper and titanium sheet are investigated using both experimental and numerical methods. A fully 3-D finite element mode is proposed to simulate the transient deformation behaviors. The effects of material and laser energy on the deformations are investigated experimentally. Thickness distribution at the cross-section of the micro-channel is analyzed experimentally. Strain states during micro-embossing are used to interpret the variation in thickness distribution. Fracture along the inner edges of the micro-mould occurs for 8 μm copper when the pulse energy is 1200 mJ, 1380 mJ and 1550 mJ. Moreover, the 13 μm titanium is completely sheared off along the inner edge of the micromould when the pulse energy is 1550 mJ. With further development, the laser-driven flyer technique can realize the blanking forming. And experimental data obtained are then used to validate the corresponding simulation model. The results show that the finite element analysis can predict the final shape of the work piece properly.

Laser shock welding of aluminum/aluminum and aluminum/copper plates

Co-reporter:Xiao Wang, Chunxing Gu, Yuanyuan Zheng, Zongbao Shen, Huixia Liu

Materials & Design 2014 56() pp: 26-30

Publication Date(Web):April 2014

DOI:10.1016/j.matdes.2013.10.091

•Laser shock welding have been investigated experimentally for small scales parts.•The wavy interface and flat wave were observed for same and different metals.•The micro-hardness of the welding interface zone increased after laser shock welding.This work describes an advanced technique for metal welding and composite production, namely laser shock welding. A series of laser shock welding experiments were conducted to verify the welding ability of aluminum/aluminum and aluminum/copper plates. Two kinds of interface morphologies were observed by metallographic investigation on cross-sections of the joint areas, including the linear and wavy interfaces. Besides, micro-hardness testing results show the welded interface has a much greater hardness than the base metals. The lap shearing test was used to characterize the joint. According to the experimental results, it can be imply that this kind of technique shares the same bonding mechanism with explosive welding and magnetic welding.

Investigation of the relationships of process parameters, molten pool geometry and shear strength in laser transmission welding of polyethylene terephthalate and polypropylene

Co-reporter:Xiao Wang, Hao Chen, Huixia Liu

Materials & Design 2014 55() pp: 343-352

Publication Date(Web):March 2014

DOI:10.1016/j.matdes.2013.09.052

•FEM is used to simulate the LTW process and is validated by the experiments.•The molten pool geometry (both width and depth) are studied in detail by FEM.•RSM models are developed between process parameters and responses of interest.•The interaction effects of process parameters on the WW and DTA are investigated.•The influence of molten pool D/W ration on the shear strength is firstly studied.This study concerns the laser transmission welding (LTW) of polyethylene terephthalate (PET) and polypropylene (PP) which are widely used in the automotive, aerospace and medical industries. The relationships of process parameters, molten pool geometry (both width and depth) and shear strength (SS) in LTW process are systematically investigated through finite element method (FEM), response surface methodology (RSM) and experiments. Thereinto, the relationships between the molten pool depths to width (D/W) ratio and SS are firstly investigated. Firstly, a three-dimensional thermal model is developed to simulate the temperature field and molten pool geometry of the LTW process. The simulation results are confirmed by experiments. Then RSM is utilized to design the experiments and establish the mathematical relationships between the process parameters and molten pool geometry based on the simulation results. The interaction effects of the process parameters on the molten pool geometry are analyzed. Finally, the simulation results are further used for searching the relationships between the molten pool D/W ratio and the SS (from tensile experiments). The maximum value of the SS and the corresponding molten pool D/W ratio is found. The result reveals that the molten pool D/W ratio has a significant influence on the SS. Moreover, this finite element model can also play a commendable guiding role in the LTW experiments with acceptable accuracy.

Simulation and optimization of continuous laser transmission welding between PET and titanium through FEM, RSM, GA and experiments

Co-reporter:Xiao Wang, Hao Chen, Huixia Liu, Pin Li, Zhang Yan, Chuang Huang, Zhenuan Zhao, Yuxuan Gu

Optics and Lasers in Engineering 2013 Volume 51(Issue 11) pp:1245-1254

Publication Date(Web):November 2013

DOI:10.1016/j.optlaseng.2013.04.021

•An intelligent method for simulation and optimization of LTW process is studied.•FEM model is constructed to simulate the temperatue field of LTW process.•RSM models are developed between process parameters and welding quality variables.•DF integrated with NSGA-II is used to find out the optimized process parameters.•The integrated approach involves FEM, RSM, GA and experiments (EX).An intelligent method for simulation and optimization of continuous laser transmission welding (LTW) and validated with experiments (EX) is investigated in this paper. Thermal model using finite element method (FEM) has been combined with response surface methodology (RSM) and genetic algorithm (GA) techniques to improve veracity of the model prediction with less time spending on the experiments. A three-dimensional axi-symmetric thermal model has been developed to simulate the continuous LTW process with a moving Super-Gaussian heat source. The model is confirmed with a series of experiments. A statistical technique RSM based mathematical model is proposed to establish relations between input variables (power, welding speed, stand-off-distance) and output variables (maximum temperature at the weld interface-Tmax, maximum temperature at the top surface of the transparent PET-Ttop, weld width-WW, and weld depth in the transparent PET-DT). The RSM models are trained and tested by using the data from the numerical (FEM) models. It turns out that the models are proposed to accurately predict the output variables with the corresponding input variables. Finally, the desirability function (DF) integrated with the developed non-dominating sorting genetic algorithm-II (NSGA-II) is used to find out the optimal variables that enhance the quality and efficiency of the welding. Experiments using the optimum parameters are carried out to verify the FEM and RSM models. Results show that the proposed integrated (FEM–RSM–GA–EX) approach performed very well in optimum performance of the continuous LTW process. In addition, this approach also presents the feasibility of the use of the FE simulation to guide the experiments.

Modeling and optimization of joint quality for laser transmission joint of thermoplastic using an artificial neural network and a genetic algorithm

Co-reporter:Xiao Wang, Cheng Zhang, Pin Li, Kai Wang, Yang Hu, Peng Zhang, Huixia Liu

Optics and Lasers in Engineering 2012 Volume 50(Issue 11) pp:1522-1532

Publication Date(Web):November 2012

DOI:10.1016/j.optlaseng.2012.06.008

A central composite rotatable experimental design(CCRD) is conducted to design experiments for laser transmission joining of thermoplastic-Polycarbonate (PC). The artificial neural network was used to establish the relationships between laser transmission joining process parameters (the laser power, velocity, clamp pressure, scanning number) and joint strength and joint seam width. The developed mathematical models are tested by analysis of variance (ANOVA) method to check their adequacy and the effects of process parameters on the responses and the interaction effects of key process parameters on the quality are analyzed and discussed. Finally, the desirability function coupled with genetic algorithm is used to carry out the optimization of the joint strength and joint width. The results show that the predicted results of the optimization are in good agreement with the experimental results, so this study provides an effective method to enhance the joint quality.Highlights► This paper is made to study the optimization of joint quality for laser transmission joining. ► ANN was used to establish the model between the process parameters and the joint quality. ► The effects of process parameters on the joint quality are analyzed and discussed. ► Finally, GA is used to conduct the optimization of the joint quality. ► This study provides an instruction to enhance the joint quality.

Multi-objective optimization of laser transmission joining of thermoplastics

Co-reporter:Xiao Wang, Cheng Zhang, Kai Wang, Pin Li, Yang Hu, Kai Wang, Huixia Liu

Optics & Laser Technology 2012 Volume 44(Issue 8) pp:2393-2402

Publication Date(Web):November 2012

DOI:10.1016/j.optlastec.2012.04.009

A central composite rotatable experimental design (CCRD) was used to plan the experiment of laser transmission joining of thermoplastic. Response surface methodology (RSM) was employed to establish the mathematical relationships between the joining process parameters (laser power, joining velocity, clamp pressure, scanning number) and the three responses (the joint strength, joint width and joint cost) and then the optimization capabilities in design-expert software were used to carry out the multi-objective optimization of the joining process. In this paper, the models were tested for adequacy using analysis of variance, the predicted errors were calculated, the effects of joining process parameters were determined, and the optimal conditions were identified. It is demonstrated that the predicted results of the optimization are in good agreement with the experimental results, so this study provides an effective instruction to enhance the joint quality and minimize the joint cost.Highlights► The multi-objective optimization of laser transmission joining of thermoplastic is researched. ► RSM was used to establish the model between the process parameters and the joint quality and cost. ► This study provides an instruction to enhance the joint quality and minimize the joint cost.

Modeling and optimization of laser transmission joining process between PET and 316L stainless steel using response surface methodology

Co-reporter:Xiao Wang, Xinhua Song, Minfeng Jiang, Pin Li, Yang Hu, Kai Wang, Huixia Liu

Optics & Laser Technology 2012 Volume 44(Issue 3) pp:656-663

Publication Date(Web):April 2012

DOI:10.1016/j.optlastec.2011.09.018

Laser joining parameters play a very significant role in determining the quality of laser transmission joining between PET films and 316L stainless steel plates. In the present work, Laser power, joining speed and stand-off-distance were considered as joining parameters. The parameters that influence the quality of laser transmission joining were optimized using response methodology for achieving good joint strength and minimal joint width. The central composite second-order Rotational Design (CCRD) has been utilized to plan the experiments and response surface methodology (RSM) is employed to develop mathematical relationships between joining parameters and desired responses. Based on the developed mathematical models, the interaction effects of the process parameters on laser transmission joining were investigated and optimum joining parameters were achieved. The experimental values nearly agree with the predicted values from mathematical models, indicates that the models can predict the responses adequately and optimize the key process parameters quickly.Highlights► PET and 316L stainless steel were joined by laser transmission joining technology. ► RSM was used to develop models between joining parameters and desired variables. ► Effects of parameters were investigated and optimum parameters were achieved. ► A theoretical foundation was laid for the promotion of laser transmission joining.

Numerical study of the mechanism of explosive/impact welding using Smoothed Particle Hydrodynamics method

Co-reporter:Xiao Wang, Yuanyuan Zheng, Huixia Liu, Zongbao Shen, Yang Hu, Wei Li, Yangyang Gao, Chao Guo

Materials & Design 2012 35() pp: 210-219

Publication Date(Web):

DOI:10.1016/j.matdes.2011.09.047