The Experts below are selected from a list of 14496 Experts worldwide ranked by ideXlab platform
Linfa Peng - One of the best experts on this subject based on the ideXlab platform.
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Micro/Meso Scale Metallic Sheet Forming Process Analysis Based on the Strain Gradient Plasticity Theory
Materials Science Forum, 2011Co-Authors: Linfa Peng, Xin Min Lai, Wei Gang ZhangAbstract:Increasing demands for miniature metallic parts have driven the application of micro/meso Forming Process in various industries. The present study focuses on the size effect which appears in the micro/meso scale Sheet Forming Process. Micro/meso scale stamping experiments and finite element simulations incorporating the CMSG plasticity theory are conducted, respectively. It is found that the numerical simulation results, with strain gradient and strain gradient path taken into account, match the experimental results better than those of conventional simulation method.
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analysis of micro mesoscale Sheet Forming Process with uniform size dependent material constitutive model
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2009Co-Authors: Linfa Peng, Jung Han Song, Jun NiAbstract:Based on accurate material models, finite element (FE) method becomes a powerful tool in conventional metal Forming Process design. However, conventional material models cannot describe the material behaviors in micro/mesoscale due to size/scale effects. As a result, most know-how obtained in traditional macroForming is not suitable for the microForming Process. In the present study, a uniform size dependent constitutive model, describing the evaluation of the material behaviors from macroscale to microscale, is established by introducing the scale factor. It contains two different terms: size dependent term and size independent term. Moreover, SUS304 Sheet specimens are prepared and uniaxial tension experiments are performed to validate the material model. Based on this uniform size dependent constitutive model, numerical simulation models of micro/mesoSheet Forming Process are established to investigate the influence of the size effects. The results show that there is obvious difference in the punch force and Mises stress distribution between the results with consideration of size effects and that without size effects. Therefore, the size effects should be considered in micro/mesoForming Process design.
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size effects in thin Sheet metal Forming and its elastic plastic constitutive model
Materials & Design, 2007Co-Authors: Linfa Peng, Jun Ni, Fang Liu, Xin Min LaiAbstract:Abstract Size effects make most know-how of traditional macro-Forming not suitable for the micro-Forming Process. Material behaviour greatly varies in micro-Sheet Forming Process with different Sheet thickness. This paper’s purpose is to establish a uniform constitutive model considering size effects in micro-Forming Process. On the basis of the uniaxial tension experiment of the CuZn36 Sheet, a uniform double-linear constitutive equation which is suitable for any thickness of the Sheet metal is put forward. Moreover, an algorithm of the VUMAT-subroutine for this constitutive model is given. By use of the constitutive model and the VUMAT-subroutine, the Forming Process of the micro-U shape is simulated, and the simulation results show that the constitutive model proposed by this paper can precisely describe the flow behaviour of the micro-Sheet metal.
Paul A. Meehan - One of the best experts on this subject based on the ideXlab platform.
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Investigation on wrinkling deformation in multi-pass incremental Sheet Forming Process
Key Engineering Materials, 2016Co-Authors: Zhao Bing Liu, Paul A. MeehanAbstract:Incremental Sheet Forming (ISF) is a promising rapid prototyping technology used to form complex three-dimensional shapes. For Forming a part with severely sloped regions, design of multi-stage deformation passes (intermediate shapes or preforms) before the final part, is widely adopted as a desirable and practical way to control the material flow in order to obtain a more uniform thickness distribution and avoid Forming failure. However, a problem sometimes encountered in multi-pass Forming is wrinkling deformation between two adjacent deformation passes. This may lead to Forming Process instability and even fracture. The overall quality of the final part may also deteriorate even if the part is formed successfully. In this paper, the wrinkling phenomenon in multi-pass incremental Sheet Forming is investigated by means of finite element analysis (FEA) and experimental tests to analyse the wrinkling formation mechanism. This research gives an insight into the optimized design of deformation passes in order to eliminate the unwanted wrinkling deformation in multi-pass incremental Forming Process.
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investigation and optimization of deformation energy and geometric accuracy in the incremental Sheet Forming Process using response surface methodology
The International Journal of Advanced Manufacturing Technology, 2015Co-Authors: W J T Daniel, Paul A. MeehanAbstract:Incremental Sheet Forming (ISF) is a promising manufacturing Process that features benefits of reduced Forming forces, enhanced formability and greater Process flexibility. It also has a great potential to achieve economic payoff for rapid prototyping applications and for small quantity production in various applications. However, limited research has been conducted from the sustainability point of view, particularly for energy consumption. More consumed energy will generate more heat and affect tool and product wear. Also, geometric accuracy is still one of the dominant limits for the further development and commercialization of the ISF technology. Therefore, the aim of this study is to investigate how different Process parameters affect the consumed energy during the Forming Process and also find the optimal working condition for lower deformation energy with higher geometric accuracy. A Box-Behnken design of 27 tests for pyramid-Forming Processes have been performed for a multi-objective optimisation that considers four factors: step down, Sheet thickness, tool diameter and wall angle at three levels. The deformation energy during the Forming Process was calculated based on the measured Forming forces. It was found that the deformation energy heavily depends on the Sheet thickness because of higher plastic energy required to deform the material. Increasing step-down size within a limited range or decreasing the wall angle is also an effective approach to reduce the deformation energy. Moreover, the effects of various Process parameters on the global geometric accuracy have also been investigated. The geometric error has been empirically predicted by quadratic equations giving the influence of the most influential Forming parameters. It was concluded that the geometric quality is largely determined by the quadratic effect of wall angle, the linear effect of Sheet thickness and the interaction effect of thickness and step down. Finally, the optimal working conditions for both independent and simultaneous minimisation of deformation energy and geometric error during the pyramid-Forming Process are provided.
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tool path strategies and deformation analysis in multi pass incremental Sheet Forming Process
The International Journal of Advanced Manufacturing Technology, 2014Co-Authors: Yanle Li, Paul A. MeehanAbstract:Incremental Sheet Forming (ISF) is a new promising manufacturing technology with high potential to shape complex three-dimensional parts by using a relative small tool. However, ISF is presently limited due to non-uniform thickness distribution of formed parts, especially excessive thinning on severely sloped regions. This typically leads to fracture and hence limits Process formability. This paper aims to tackle this issue by developing appropriate tool path strategies for multi-pass deformation design in ISF. More specifically, two more complex shapes are designed to validate the proposed multi-pass deformation design methodology by finite element simulations and experiments. The interactions of different tool path strategies on material thinning of the final part are evaluated in terms of Process formability and thickness strain distribution given the same multi-pass design. Furthermore, the movement of material points is traced to explain the material flow mechanism in multi-pass Forming compared to single-pass Forming. It is concluded that both deformation passes (intermediate shapes) and tool path generation strategies would influence the thickness strain distribution as well as Process formability. Appropriate tool paths should be devised to further reduce material thinning and improve the Process formability by taking the geometrical features of the designed part into account. Additionally, the proposed multi-pass deformation design enables sufficient material to flow into the deformed region from the outside region so as to allow a compressive deformation state to develop and steeper shapes to be formed.
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simulation and experimental observations of effect of different contact interfaces on the incremental Sheet Forming Process
Materials and Manufacturing Processes, 2014Co-Authors: Zhao Bing Liu, W J T Daniel, Paul A. MeehanAbstract:Incremental Sheet Forming (ISF) is a promising Forming Process perfectly suitable for manufacturing customized products with large plastic deformation by using a simple moving tool. Up to now, however, the effects of contact conditions at the Sheet interface are not well understood. The aim of this work is to study the effect of tool type and size on the formability and surface integrity during the Forming Process. Experimental tests were carried out on aluminum Sheets of 7075-O to create a straight groove with four different tools (ϕ 30,ϕ25.4,ϕ20 andϕ10mm). One tool tip was fitted with a roller ball (ϕ 25.4mm) while the other three were sliding tips. The contact force, friction and failure depth were evaluated. A finite element (FE) model of the Process was set up in an explicit code LS-DYNA and the strain behavior and thickness distribution with different tools were evaluated and compared with the experimental results. This study provides important insights into the relatively high formability observed ...
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Study on Step Depth for Part Accuracy Improvement in Incremental Sheet Forming Process
Advanced Materials Research, 2014Co-Authors: Zhao Bing Liu, Sheng Liu, Paul A. MeehanAbstract:Incremental Sheet Forming (ISF) is a new-emerging Sheet Forming Process well suited for small batch production or prototyping because it does not need any dedicated dies or punches. In this Forming Process, Sheet metal parts are formed by a smooth-end tool in a stepwise way, during which plastic deformation is highly localized around the tool end. The part geometric accuracy obtained in the current ISF Process, however, has not met the industry specification for precise part fabrication. This paper deals with a study on step depth, a critical parameter in ISF, for improving the geometric accuracy, surface quality and formability. Two sets of experiments were conducted to investigate the influence of step depth on part quality. Dimensional accuracy, surface morphology and material fracture of deformed parts were compared and analysed. An optimum value of step depth was suggested for Forming a truncated cone. The present work provided significant fundamental information for the development of an advanced ISF control system on tool path control and optimization.
Rui Jie Gu - One of the best experts on this subject based on the ideXlab platform.
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a new method to accurately obtain wrinkling limit diagram in nc bending Process of thin walled tube with large diameter under different loading paths
Journal of Materials Processing Technology, 2006Co-Authors: H Li, He Yang, Mei Zhan, Rui Jie GuAbstract:Abstract To obtain the wrinkling limit of thin-walled tube by the NC bending Process analytically, a new method has been proposed. Firstly, an FE model using ABAQUS/Explicit is employed to simulate the complex Forming Process. Thus, the plastic deForming behavior and wrinkling mechanism for thin-walled tube with large diameter under different loading paths (with or without boosting device) has been investigated and the reasonable assumptions for analytical analysis have been obtained. Secondly, according to the above simulation, an analytical wrinkling prediction model based on an energy criterion is established to calculate the wrinkling limit. Thirdly, an exponential function has been used to compensate for the effects of boundary conditions on onset of wrinkling by comparing the analytical results with corresponding numerical results to make the final results closer to reality. Thus the winkling limit diagrams with band distribution features are calculated. The method proposed is more suitable to the evaluation of formability for complex Sheet Forming Process concerning wrinkling.
Zhong Zhi Hua - One of the best experts on this subject based on the ideXlab platform.
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optimization of Sheet metal Forming Processes by adaptive response surface based on intelligent sampling method
Journal of Materials Processing Technology, 2008Co-Authors: Wang Hu, Li Guang Yao, Zhong Zhi HuaAbstract:Abstract In this study, the previously developed adaptive response surface method (ARSM) is suggested for construction of metamodel for highly non-linear responses. In order to develop the accuracy and efficiency of metamodel, the particle swarm optimization intelligent sampling (PSOIS) scheme is developed. This kind of intelligent method can guarantee the sampling search in right direction and constraint the bounds of design variables in feasible region. For validation of developed method, the Rosenbrock function is successfully approximated by proposed method; corresponding metamodel appropriateness can be well predicted by analysis of variance (ANOVA). Metamodel by ARSM with PSOIS are employed for optimization of initial blank shape and blank hold force (BHF) in Sheet Forming Process, with validations by finite element simulations using LSDYNA970 commercial code. The results show that developed method is able to produce remarkable metamodels for highly non-linear problems with multi-parameter.
Xin Min Lai - One of the best experts on this subject based on the ideXlab platform.
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Micro/Meso Scale Metallic Sheet Forming Process Analysis Based on the Strain Gradient Plasticity Theory
Materials Science Forum, 2011Co-Authors: Linfa Peng, Xin Min Lai, Wei Gang ZhangAbstract:Increasing demands for miniature metallic parts have driven the application of micro/meso Forming Process in various industries. The present study focuses on the size effect which appears in the micro/meso scale Sheet Forming Process. Micro/meso scale stamping experiments and finite element simulations incorporating the CMSG plasticity theory are conducted, respectively. It is found that the numerical simulation results, with strain gradient and strain gradient path taken into account, match the experimental results better than those of conventional simulation method.
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size effects in thin Sheet metal Forming and its elastic plastic constitutive model
Materials & Design, 2007Co-Authors: Linfa Peng, Jun Ni, Fang Liu, Xin Min LaiAbstract:Abstract Size effects make most know-how of traditional macro-Forming not suitable for the micro-Forming Process. Material behaviour greatly varies in micro-Sheet Forming Process with different Sheet thickness. This paper’s purpose is to establish a uniform constitutive model considering size effects in micro-Forming Process. On the basis of the uniaxial tension experiment of the CuZn36 Sheet, a uniform double-linear constitutive equation which is suitable for any thickness of the Sheet metal is put forward. Moreover, an algorithm of the VUMAT-subroutine for this constitutive model is given. By use of the constitutive model and the VUMAT-subroutine, the Forming Process of the micro-U shape is simulated, and the simulation results show that the constitutive model proposed by this paper can precisely describe the flow behaviour of the micro-Sheet metal.