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A variety of micro forming processes has been invented, and the size effects have become a research hotspot at home and abroad. Micro bending molds with different feature sizes were designed. Quasi-static tester loading and dynamic laser shock loading with soft punch for micro bending forming was studied by numerical simulation respectively based on ANSYS implicit analysis and LS-DYNA explicit analysis. The constitutive models of workpiece are bilinear kinematic hardening model and Johnson-cook model respectively. The effects of different loading conditions and feature sizes of the die on the forming depth, equivalent plastic strain and equivalent plastic strain rate were studied. The results of numerical simulation show that, with the increasing of feature size of the mold, the forming depth under two kinds of loading conditions shows a tendency to increase. In dynamic laser shock loading, the equivalent plastic strain and equivalent plastic strain rate of the key position of the bent part would decrease with the increasing of the feature size of the die. While in quasi-static loading, the opposite law is shown. The research shows that, the flexible micro-bending processes with different loading models showed similar size effect. However, compared with quasi-static loading, in dynamic loading, the strain of forming parts is more centralized, and there is a high strain rate and better formability of the workpiece.

Based on the laser-driven flyer micro forming and laser high-speed impact welding, this paper put forward the laser high-speed impact synchronous welding and forming new process, and builds the compound welding experiment platform. The three-dimensional deep field digital microscope of KEYENCE VHX-1000C was used to measure the surface morphology and the maximum deformation depth of the welding and formingsamples. By observing the surface morphology of the sample, it was found that strong plastic deformation occurred on the surface of the materials and well reproduced the shape of the mold. When the laser energy was below 4.5J, the maximum deformation depth of the samples increased with the laser energy. However, the maximum deformation depth decreased due to the spring back phenomenon when the laser energy was larger than 4.5J. The Axio CSM 700 confocal microscope was used to measure the morphology of the welding interface. The cross profile of the welding interface showed that most regions had been welded and the welding interface was nearly flat.

Joining between polyamides (PA) and metals has potential applications in the industry. Based on PA66GF and AISI304, the experimental study of laser transmission joining of the dissimilar materials is conducted in this article. Firstly, comprehensive experiments of laser transmission joining between PA66GF and AISI304 are carried out by Nd: YAG pulsed laser source according to the central composite rotatable design method (CCRD). Secondly, the effects of the process parameters like voltage, joining speed and stand-off distance on the joint quality are analyzed by response surface methodology (RSM). Finally, mathematical models between the process parameters and the lap-shear strength and the joint width are established and based on which, the optimization of the joining process is done and the optimized results are predicted. The results show that the process parameters of laser transmission joining play a significant role in determining the joint quality; the predicted data of the models are in good agreement with the experimental results and can be of great help for the optimization of the joining process. As a result, this study could provide an effective instruction about how to choose the reasonable process parameters for enhancing the joining efficiency.

Light scattering of the upper polymer have a great influence on welding quality. Light scattering of high density polyethylene (HDPE) and low density polyethylene (LDPE) are assessed by constructing experiment and numerical computation method. Firstly, the beam quality of semiconductor laser is analyzed, power flux distribution of the laser beam in a defocused plane is measured by knife edge method; Afterwards, the power flux distributions of the laser beam after passing through HDPE/LDPE are measured by line scanning method; Lastly, with the combination of the mathematical model which is used to calculate scattering coefficient and standard deviation of scattering, scattering related parameters and the laser power flux distribution at the welding interface are obtained by writing a program in MATLAB. The results show that the light scattering coefficient of high density polyethylene is up to 0.988, the light scattering coefficient of low density polyethylene is 0.92; Higher crystalline polyethylene leads to more obvious light scattering; the laser beam power flux distribution at the weld interface affected by scattering is determined, which lays a solid foundation on numerical simulation in laser transmission welding.

The pyrolysis kinetics parameters of material had an great importance on estimating material degradation during laser transmission welding. The PA66/CB was produced using a twin-screw extruder, and thermogravimetric experiment of PA66/CB was performed at different heating rate of 5, 10, 15 and 20 °C/min, then the pyrolsis behavior and pyrolysis kinetics parameters of material were investigated based on the Kissinger, Starink and Freeman-Carroll three methods. The results showed that the pyrolsis process of PA66/CB was one step reaction. With the increase of heating rate, the initial reaction temperature and final pyrolsis temperature of TG curve and the peak temperature of DTG curve were shift to higher temperature. Temperature hysteresis was appeared but the final pyrolsis rate was not affected by heating rate. The activation energy on the biggest pyrolsis rate was not affected by the addition of carbon black. The activation energy calculated using Starink method was increased by the increase of conversion rate. The activation energy calculated using Freeman-Carroll method was bigger than Kissinger and Starink methods. The activation energy was calculated using Freeman-Carroll method, then using the nthmodel, and the pyrolsis kinetic equation was expressed as:dα/dt=2.053×1019[exp (-245.32×103/RT)](1-α)2.22.

Laser transmission welding (LTW) is a new and efficient technology. During LTW of polymers, the size and morphology of the weld have great influence on the welding quality. In order to better evaluate the welding quality and optimize process parameters, many researches on the morphology and mathematical analytical model of the molten pool have been conducted. This study attempts to build an analytical model for calculating the depth of the molten pool (molten depth), based on the temperature field distribution theory of the moving point heat source acting on the semi-infinite body. The influence of the welding power and welding speed on the molten depth is studied emphatically. The mathematical analytical model is solved through MATLAB mathematical software. Subsequently, the test experiment about LTW of PA66 is conducted to validate the model. During the test experiment, the upper layer contains 30 wt. % glass fibers (GF) and the bottom layer contains 30 wt. % carbon fiber (CF). The result shows that the mathematical analytical model can well predict the trend of the molten depth. However, the error exists indeed. The detailed analysis about the error is also made in this article.

Laser shock micro-adjustment is a precise and noncontact adjustment technique using laser-shock-waves to adjust the curvature of micro-components. The experimental studies have indicated that: when laser shock region is located at the free end of cantilevers, multiple impacts are applied to achieve a large bending degree; meanwhile, different bending directions can be obtained with multiple impacts in the junction position. Efforts should been made to understand the mechanisms of multiple laser shock micro-adjustment. Two mechanisms have been proposed for describing the laser shock micro-adjustment in different laser shock regions, namely shock inertia mechanism and material flow mechanism. The proposed micro-adjustment mechanisms can predict bending angles and directions. To validate the proposed micro-adjustment mechanisms, numerical simulations were carried out based on the FEM method using the ANSYS/LS-DYNA software and the corresponding results demonstrate the proposed mechanisms.

A laser direct joining (LDJ) experiment of titanium alloy (Ti-6Al-4V) and carbon fiber reinforced nylon (PA66CF20) is presented here using diode laser equipment. Experimental design and experiment of LDJ are carried out according to a single process parameters range obtained from the previous experiment. Response surface methodology (RSM) in Design-Expert v7 software is adopted to establish the mathematical model between LDJ process parameters and joint quality. Then the interaction effects of joining process parameters (laser power, scan speed and stand-off distance) on joint quality are investigated using analysis-of-variance (ANOVA), and the result shows that the interaction effect of laser power and scan speed on joint quality is the greatest. Finally, the predicted values from the mathematical model established by RSM are compared with the experimental values, and the process parameters are optimized to obtain the strongest joint strength. The result suggests that the predicted values are in good agreement with the experimental ones. The purpose of predicting and optimizing joint quality based on reasonable process parameters is achieved.

Laser impact welding (LIW) is a novel welding technique which uses laser induced shock waves to obtain the solid-state and metallurgical bonding between flyer and base plates, and can be applied in welding of dissimilar metal plates in micron level. In this paper, experimental study is conducted with titanium as the flyer plate and aluminum as the base plate under different laser energies and laser spot diameters. Besides, the microstructure and mechanical properties of the welding joints are also investigated. The wavy interface is observed by metallographic investigation which is similar to explosive welding and electromagnetic pulse welding. Moreover, the micro-hardness taken from the interface region shows an obvious improvement compared with the base metal. It is also found that laser shock welding results in fine grained structure of titanium on the weld interface. In conclusion, laser shock welding can not only improve the material microstructure of weld interface, but also avoid the heat affected zone and formation of intermetallic phase during dissimilar metal welding. Therefore, it is a promising welding technology in the field of MEMS.

White body in the design process needs to meet the needs of a wide range of performance requirement. Adequate stiffness and modal are the basis to ensure the vehicle’s performance of vibration noise. Simultaneously, in order to reduce energy consumption and cost, the lightweight design of the white body has become the mainstream. In this paper, the optimization design is conducted for stiffness and modal of a commercial vehicle’s white body based on the theory of the finite element size sensitivity optimization design. Firstly, build the finite element model of a vehicle’s white body and analyze its stiffness and modal. Some changes were made to the car-body’s partial structure according to the distributing of strain energy achieved from above analysis, which improved the car-body’s dynamic and static performance initially. Secondly, choose panels needed to be optimized by reference to the density of strain energy and panels’ mass. Then, the car-body’s structure was optimized using panels’ thickness as design variables, stiffness and modal frequencies as constrains and minimizing weight of white car-body as objective. After the analysis of the result, modal separation was put forward to improve the quality of this finite element optimization design model. Finally, the car-body’s stiffness and mode nature entirely satisfied the requirements with car-body’s weight decreased.

This paper presents an experimental study to evaluate the feasibility, characteristics and mechanism of laser direct joining between metal and carbon fiber reinforced plastic (PA66CF20). This study presents a method to improve the joint strength of the metal-polymer hybrid joint. The investigation study effects of process parameters (laser power and travelling speed) on the quality of joining joint. Macroscopic morphology of joint and PA66CF20 melting region closed to the interface were observed in this study. XPS analysis shows that Ti-C and Ti-O chemical bonding were produced between titanium alloy and plastic. Cross-sectional photo showed the melted polymer flowed into micro-cavity of metal surface caused by roughness of metal and thus formed mechanical bonding. Finally, the titanium alloy surface was structured in four different surface textures using a pulsed laser. Then the metal was joined with the plastic. The result shows that the joint strength of metal after laser-structured joining with plastic had been improved greatly.

With the demand of high-quality and aesthetical products in the domain of medical microbiology, it’s more and more important to join micro weld. Due to traditional joining methods’ difficulty in meeting the demands, laser transmission micro-joining is of great significance. The materials used to laser transmission micro-joining based on the mask are PET, and the experiments are conducted on diode laser. The weld geometry with different gap widths on the mask is demonstrated at the same process parameters. In addition, the causes of forming different morphologies are analyzed. The formation mechanism of weld is analyzed as well. Moreover, process parameters’ effects on joint strength and joint width are deeply explored when gap width on the mask is 0.3mm. The results show that100 um micro weld joint is realized. At the same time, the range of process parameters is determined.

This article uses semiconductor laser for mask assisted laser transmission micro joining PET and PET with clear weld absorbents, the mask slit width is 0.3mm, using CCD to plan experimental design. The mathematical model of joining process parameters with joint strength and joint width was established using response surface methodology. Experimental verification was also done. The actual joint width was compared to mask slit width and the process parameters were optimized. The results show that the mathematical model can response the relationship between process parameters and joining quality, the mask can effectively control the joint width, reasonable process parameters can obtain high-precision, high-intensity joining quality.

Laser-driven flyer micro forming process is a promising microforming technology with the advantage of high efficiency, low cost, high flexibility. A series of experiments are conducted to investigate forming ability of aluminum foil with the thickness of 50μm. The effect of forming temperature and laser energy on forming ability characterized by forming depth, forming accuracy and surface quality is quantitatively analyzed. It is found that forming depth observed through three dimensional topography increases with the enhancement of forming temperature and laser energy. By elevating the forming temperature, the preheated workpiece suffers more homogenous deformation, presenting better forming accuracy. However, a certain degree of deterioration of surface integrity at the forming temperature of 200°C can be attributed to the earlier appearance of micro cracks caused by excessive thinning even at low laser energy. Overall, it is concluded that the optimal forming temperature is appropriately 150°C as the forming depth and forming accuracy is improved with no deterioration of the surface integrity.

In this paper,the laser transmission joint strength is studied with semiconductor laser based on the surface pitting of 304 stainless steel and PA66.Unevenly distributed pits are formed on the surface of 304 stainless steel with 10% ferric chloride solution for two hours, which have certain morphology, depth and size. Different laser power, welding speed and welding pressure are used in laser transmission joining 304 stainless steel and PA66,which 304 stainless steel contains pitting corrosion before and after. The tensile strength test of joined samples shows that: the joint strength of pitted 304 stainless steel and PA66 with laser transmission joining is improved at least 135%; the riveted structure formed at the joining interface improve the joint strength.

Due to the change of car-body design, the location of exhaust systems hanger is uncertain and always fluctuates around the initial design position. So the Taguchi method is introduced to conduct exhaust systems optimal design. Firstly, the parameterization of hanger location under the grid environment was realized by combining NastranHypermesh and Isight. Then, the Taguchi robust design of the exhaust system is performed taking the hanger location as noise factors and the stiffness of hanger shock absorber as control factors. As a result, modal property and robustness of the exhaust system are improved. At last, the results of Taguchi robust design and traditional sensitivity optimization design based on the finite element method are compared, which reveals the advantage of Taguchi robust design in improving product quality.

Based on the CFD-FSI fluid-solid coupled method, the equivalent elastohydrodynamic lubrication model of the micro-texturing dimple surface on the condition of the medium velocity and medium load, low velocity and heavy load, high velocity and heavy load, low velocity and light load and high velocity and light load is respectively solved by numerical method in this paper. And obtain the oil film pressure distribution curve and the oil the film thickness distribution curve on the conditions of steady state, and analyze the influence of micro-texturing dimples on the bearing capacity of the equivalent elastohydrodynamic lubrication model. Analysis results show that: compared with the corresponding minimum film thickness on the conditions of smooth surface, the minimum film thickness of micro-texturing dimple surface on the conditions of the medium velocity and medium load, low velocity and light load is increased, which indicates the bearing capacity of the equivalent elastohydrodynamic lubrication model of the micro-texturing dimple surface is increased; while the minimum film thickness of the rest conditions is decreased, which shows that the bearing capacity of the equivalent elastohydrodynamic lubrication model of the micro-texturing dimple surface is decreased. The study in this paper lays the foundation for the design and optimization of the micro-texturing dimple.

A FE model is built based on one vehicle door, the thickness of door's main components for absorbing energy is considered as the design variable. Firstly, a screening experiment is implemented by using Plackett-Burman design, and the prominent components for crashworthiness are selected. Then, the Latin hypercube experiment design is performed again. The approximation model of polynomial response surface is built by the Least Squares Regression according to the experimental results. At last, the approximation model, of which the objective function are the maximum internal energyand the minimum mass sum of all variables, and the constrain function is the maximum impact force, is optimized by using multi-objective Genetic Algorithm (MOGA). The results of the optimization show that the mass of all design variables and the max impact force are reduced by 4.12% and 4.43%, respectively, and the maximum internal energy is increased by 2.3%. The crashworthiness of vehicle door is improved, and it provides the technological support for the safety and light weight design of the whole vehicle door.

In this paper, cold-rolled T2 copper foils with the thickness of 50 were chosen. The foils were annealed at different temperatures, namely, 250°C, 350°C, 450°C, 550°C, respectively. Micro deep drawing experiments on cold-rolled foils and annealed foils by laser driven flyer were achieved in order to investigate annealing effects on the formability of T2 copper foil. The forming depth and material flow uniformity of the workpiece at different conditions were compared and analyzed. The test results showed that: (1) The workpiece of cold rolled foil indicates poor neutral, non-uniform material flow, smaller forming depth, it is due to that the microstructures of cold-rolled foil are fiber organizations, which leads to poor plastic deformation capacity.(2)Annealing can significantly improve the formability of the foil. In the first stage : 250-350°C, recovery and recrystallization occurred in succession in the organization of the raw material, fibrous tissue transformed into equiaxed grains, the residual stress is greatly reduced, thus, the plastic deformation capacity is recovered. The forming depth is also significantly improved, increasing by about twice. In the second stage: 350-450°C, the enhanced formability is relative to the surface layer effect, which is also a reflection of micro-scale effect. This study provided a theoretical and experimental guidance for the practical application of micro deep drawing process by laser driven flyer.

This paper presents a laser transmission joining (LTJ) experiment between thermoplastic Polycarbonate (PC) and glass reinforced nylon (PA66GF) using diode laser equipment. Laser transmission joining experimental design and experiment are carried out according to a single process parameters window. Response surface methodology (RSM) in Design-Expert v7 software is employed to develop mathematical models between LTJ process parameters and joint strength. The interaction effects of joining process parameters (line energy, spot diameter, clamp pressure) on the joint strength are investigated using analysis-of-variance (ANOVA), the result shows that the interaction effect of line energy and spot diameter has maximum influence on the joint quality. Finally, the predicted values from mathematical models developed by RSM are compared with the experimental values and it is found that they are nearly agreed with each other. The purpose of predicting joint strength based on reasonable process parameters is achieved.

In this paper, the process of laser transmission joining (LTJ) of polycarbonate (PC) and polyformaldehyde (POM) which are thermoplastic plastics is investigated through a finite element (FE) simulation. Firstly, a 3D thermal model is developed with a moving Super-Gaussian heat source based on the ANSYS parametric design language APDL and the distribution of the temperature field is obtained. Then the effect of process parameters namely laser power, scanning speed and spot diameter on the joint width is analyzed. At the same time, the calculated joint width is achieved. Finally, the curves of calculated results are compared with the curves of experimental results. The comparison shows a good agreement between them which shows that the FE model is reliable. This lays the foundation for reducing experimental times, designing of experiments based on FE simulation and optimizing process parameters.

We prepared the polyaniline@polypyrrole (PAn@PPy) conductive composite by a novel method. The struction like Pre-prepared PAn as the core and PPy as the shell for the composite has been prepared by in-situ polymerization. The PAn@PPy conductive composite presents an electrical conductivity of 12.5 S/cm, which is much higher than pure PAn. The synthesized polymer composites are characterized by Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and Thermogravimetric analysis (TG). The results indicated that PPy successfully grafted on PAn and the heat resistance of nanocomposite is remarkably increased.

Two different methods, heat fusion process and solution infusion process had been used to synthesize a kind of phase change material (PCM) for latent heat thermal energy storage (LHTES). The composite was composed by steraric acid (SA) and montmorillonite (MMT). The morphology of the SA/MMT was characterized by scanning electron microscope (SEM) and FT-IR. The thermal performance and stability of the composite was characterized by differential thermal scanners (DSC) and heating store/release experiment. The FT-IR results demonstrated the PCMs and MMT combined by only physical bonds, SEM results showed that SA was intercalated in to MMT, and heat fusion process was contribute to the combination better than the other. The heating store/release experiment indicated that the stability of M-SA/MMT is better than S-SA/MMT.

Fe2O3/attapulgite(ATP) catalyst was successfully prepared for Fenton reaction to degrade an anion surfactant, sodium dodecyl benzene sulfonate(SDBS)，in an aqueous solution. BET, SEM, FT-IR were performed to characterize Fe2O3/ ATP catalyst. Comparative studies indicated that the SDBS degradation ratios were much higher in presence of Fe2O3/ATP and H2O2 than those in presence of Fe2O3/ATP or H2O2 only, which suggested that the Fe2O3/ATP-catalyzed Fenton-like reaction governed the SDBS removal process. It also can be seen that Fe2O3/ATP-catalyzed Fenton-like reaction almost has the same efficiency as homogeneous Fenton reaction, while the former can be reused and has no secondary pollutants.

The film spallation, a typical film / substrate failure style, could be caused by many reasons. The strong impact on the film/substrate can also lead to this failure phenomenon. So the film spallation induced by the strong impact is explored in this paper. Here the strong impact comes from the laser-driven flyer loading. In the numerical simulating process, the Finite Element Method (FEM) and Johnson-Cook material constitutive model have been used, moreover, some ideal film spallation results were got, which are helpful for us to understand this failure phenomenon.

The existing studies based on 2-dimension cutting model are partial investigations on tool wear. In order to get close to the true cutting conditions, the Lagrangian thermo-viscoplastic cutting simulations were conducted and the tool wears were predicted under different cutting speeds using 3-dimension finite element models. The simulation results indicate that when the cutting speed increases the cutting forces will reduce accordingly while the wear depth will be deeper. As a result, different factors should be considered at the same time when the speed range is selected. This study has shown that the finite element method is a valuable approach to understand the tool wear mechanism in machining and the influences of different cutting speeds.

Based on premixed high pressure water jet cutting, five kinds of nozzle models were established, and the control equations and closed equtions of liquid-solid two-phase were given. The inside-outside liquid-solid two-phase flow characteristics of the nozzles were simulated by Hybrid Finite Analytic Method (HFAM). The results indicate that the taper-beeline nozzle has better convergence characteristic, good hydraulic characteristic and lower radical velocity, thus it is more suitable for premixed high pressure water jet cutting nozzle.

To prevent or reduce the formation of burr efficiently in metal cutting, it is necessary to reveal the burr formation mechanism. A finite element model of cutting-direction burr formation in orthogonal machining was presented in this paper. The simulation of the burr formation process was conducted. Undeformed chip thickness, rake angle, rounded cutting edge radius and workpiece material were included in cutting conditions, whose influences on burr formation were investigated, according to the simulation results. By comparing the results of the simulation and the experiment, good consistency is achieved which proves that the finite element model of burr formation in this paper is significant and effective to predict burr formation.

Two 3-D finite element models of coated tool and uncoated tool were established using the finite element code DEFORM-2D based on the updated Lagrangian formula. And their machinability on high speed orthogonal machining was simulated and compared. The investigation results indicate that the coated tool has higher surface temperature and lower inside temperature compared with the uncoated tool. Moreover, the cutting forces of the model using coated tool are lower than that using uncoated tool.

Both micro- and meso-scale structures are involved in the analyses of many composite materials such as filament-wound tubes. In this paper, a unified approach for applying periodic boundary conditions to micro/meso-scale repeated unit cell models in the finite element analysis is presented. As an application example, a two-scale analysis of a ±θ helical filament-wound tube is provided.

The high specific strength of the magnesium alloy makes it a valuable choice for automotive, aerospace and sporting industries, where the weight reduction is a critical consideration in design. However, wrought magnesium alloys offer a poor formability at room temperature and a hot working condition is required for the forming process. This paper studies the application of finite element methods for the simulation of the forging of magnesium alloys. Numerical analysis of the forging process of an automotive magnesium wheel is conducted based on the tested flow curve of AZ80. The effect of friction on the final deformation of the upsetting of magnesium billets is also discussed.

Traditional forming process of sheet metal is realized with Die and Mould, this technique lacks flexibility and used in the Volume production. The forming process of sheet metal based on laser shock waves is a novel and developing technique. Laser shock forming (LSF) and Laser peen forming (LPF) are two different forming process of sheet metal, both of them are based on a mechanical effect of shock waves induced by laser. In this paper, after introducing the mechanism of laser shock wave generating, these two forming process and technique feature are analyzed and compared, some research progresses are presented. It is indicated that forming technique based on laser shock waves are of high-flexible and great potential application in the fields of plastic forming of sheet metal.

Laser peen forming of sheet metal is a new plastic forming technique based on laser shock waves, which derives from the combination of laser shock processing and conventional shot peening technique, it uses high-power pulsed laser replacing the tiny balls to peen the surface of sheet metal, when the laser induced peak pressure of shock waves exceeds the dynamic yield strength of the materials, the sheet metal yields, resulting in an inhomogeneous residual stresses distribution in depth. The sheet metal responds to this residual stress by elongating at the peened surface and effectively bending the overall shape. On the basis of analyzing the mechanism of laser peen forming, the line-track-peening experiments of 45 steel sheets with 2 mm thickness were carried out; a curved sheet metal with deep layer of residual compressive stress was obtained. The preliminary experiment result shows that laser peen forming can offer desirable characteristics in shaped metals and is a valuable technique for producing components for a range of industries.

A new type of limiting current oxygen sensor which uses yttria (8%mol) stabilized zirconia (YSZ) as oxygen ion conducting solid electrolytes and dense La0.8Sr0.2FeO3 (LSF) as diffusion barrier was developed successfully. The oxygen sensor shows excellent performance at oxygen concentrations range of from 0 to 21%. The advantages of the sensor are simple construction, low cost and potential long term stability.