AN INTEGRATED MICROMECHANICS MODELLING APPROACH FOR MICRO-FORMING SIMULATION

2008 ◽  
Vol 22 (31n32) ◽  
pp. 5907-5912 ◽  
Author(s):  
W. ZHUANG ◽  
J. LIN
Keyword(s):  
Voronoi Tessellation ◽  
Control Variable ◽  
Integrated System ◽  
Physical Parameters ◽  
Micro Forming ◽  
Forming Process ◽  
Forming Simulation ◽  
Localized Necking ◽  
Micro Parts ◽  
Microstructure Of The Material

An effort has been made to create an integrated Crystal Plasticity FE (CPFE) system. This enables micro-forming process simulation to be carried out easily and the important features in forming micro-parts can be captured. Firstly, based on Voronoi tessellation and the probability theory, a VGRAIN system is created for the generation of grains and grain boundaries for micro-materials. Numerical procedures have been established to link the physical parameters of a material to the control variable in a gamma distribution equation. An interface has been created, so that the generated virtual microstructure of the material can be inputted in the commercial FE code, ABAQUS, for mesh generation. Secondly, FE analyses have been carried out to demonstrate the effectiveness of the integrated system for the investigation of uncontrollable curvature and localized necking in extrusion of micro-pins and hydro-forming of micro-tubes.

An Integrated Approach for Virtual Microstructure Generation and Micro-Mechanics Modelling for Micro-Forming Simulation

2007 ◽  
Author(s):  
Kar Cheong Ho ◽  
Nan Zhang ◽  
Jianguo Lin ◽  
Trevor Anthony Dean
Keyword(s):  
Probability Theory ◽  
Crystal Plasticity ◽  
Voronoi Tessellation ◽  
Control Variable ◽  
Integrated Approach ◽  
Physical Parameters ◽  
Micro Forming ◽  
Forming Simulation ◽  
Grain Structures ◽  
Fcc Materials

To aid FE simulation for forming micro-components, an integrated approach is proposed to generate virtual microstructure for micro-mechanics modelling. Based on Voronoi tessellation and the probability theory, a VGRAIN system is created for the generation of grains and grain boundaries for micro-materials. The input data of the system are physical parameters of a material, including average, minimum and maximum grain sizes. Numerical procedures have been established to link the physical parameters of a material to the control variable in a gamma distribution equation and a method has been developed to solve the probability equation. These are the basis for the development of the VGRAIN system, which can be used to generate different grain structures and shapes that follow a certain pattern according to the probability theory. Statistical analyses have been carried out to investigate the distribution of generated virtual grains. The generated virtual microstructure is then implemented in the commercial FE code, ABAQUS, for mesh generation and micro-mechanics analysis using crystal plasticity equations for FCC materials. The crystal plasticity model is implemented in the commercial FE code, ABAQUS, through the used-defined subroutine, UMAT. FE analyses have been carried out to investigate size effects and localised necking encountered in micro-forming processes.

AN INTEGRATED CRYSTAL PLASTICITY FE SYSTEM FOR MICROFORMING SIMULATION

2009 ◽  
Vol 01 (01) ◽  
pp. 107-124 ◽  
Author(s):  
J. CAO ◽  
W. ZHUANG ◽  
S. WANG ◽  
K. C. HO ◽  
N. ZHANG ◽  
...  
Keyword(s):  
Probability Theory ◽  
Crystal Plasticity ◽  
Voronoi Tessellation ◽  
Control Variable ◽  
Integrated System ◽  
Physical Parameters ◽  
Face Centered Cubic ◽  
Grain Structures ◽  
Face Centered ◽  
Fcc Materials

Based on Voronoi tessellation and the probability theory, a VGRAIN system is created for the generation of grains and grain boundaries for micromaterials. This system requires physical parameters obtained from microstructures of materials, such as the average, minimum and maximum grain sizes. Numerical procedures have been established to link the physical parameters of a material to the control variable in a gamma distribution equation and a method has been developed to solve the probability equation. These are the basis for the development of the VGRAIN system, which can be used to generate different grain structures and shapes that follow a certain pattern according to the probability theory. Statistical analyses have been carried out to investigate the distribution of generated virtual grains. The generated virtual microstructure is then implemented in the commercial FE code, ABAQUS, for mesh generation and micromechanics analysis using crystal plasticity (CP) equations for face-centered cubic (FCC) materials, which are implemented in the commercial FE solver, ABAQUS, through the user-defined subroutines, VUMAT/UMAT. FE analyses have been carried out to demonstrate the effectiveness of the integrated system for the investigation of localized straining and necking, encountered in microforming processes, such as extrusion of micropins, deformation of microfilms and hydroforming of microtubes.

Process and Material Property Effects in the Progressive Forming of Micro-Pins

2010 ◽  
Vol 447-448 ◽  
pp. 432-436
Author(s):  
Samuel C.V. Lim ◽  
Yingyot Aue-U-Lan ◽  
Danno Atsushi ◽  
Mei Qian Chew ◽  
Chow Cher Wong
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Mechanical Property ◽  
Material Property ◽  
Significant Role ◽  
Forming Process ◽  
Forming Load ◽  
Micro Parts ◽  
Progressive Forming ◽  
Microstructure Of The Material

A progressive forming process for micro-components was developed to circumvent the issue of handling of small micro-parts while keeping in mind the need for high manufacturing through-put. The mechanical properties and microstructure of the material have been found to play a significant role in the forming of micro-components. In this work, the effect of mechanical property on the forming of copper micro-pins by the progressive forming process is highlighted. Empirical results show that the forming load decreases for forming micro-pin with 0.3mm diameter after annealing but the pin height obtainable decreases as well compared to that prior to the heat treatment.

Flow-Channel Shape Design of Stamped Bipolar Plate for PEM Fuel Cell by Micro-Forming Simulation

2006 ◽  
Author(s):  
Linfa Peng ◽  
Xinmin Lai ◽  
Jun Ni ◽  
Z. Q. Lin
Keyword(s):  
Fuel Cell ◽  
Pem Fuel Cell ◽  
Bipolar Plate ◽  
Pem Fuel Cells ◽  
Flow Channel ◽  
Micro Forming ◽  
Channel Depth ◽  
Forming Process ◽  
Forming Simulation ◽  
Punch Radius

PEM fuel cells are promising candidate as most environmentally friendly power source for transport and stationary cogeneration applications due to its high efficiency, high power density, fast startup and system robustness. But the PEM fuel cell is still too expensive for widespread commercialization. Bipolar plate is one of the most important and costliest components of PEM fuel cells and accounts to more than 80% of the weight and 30% of the total cost in a fuel cell stack. To reduce the cost and weight of fuel cell stacks and at the same time meeting several technical requirements for mass production, a prototype of low-cost stamped bipolar plates made of stainless steel 316 sheets has been introduced in this paper. Base on micro sheet forming process simulation experiments, the influence of some key dimensions of the flow channel to the formability of the stamped polar plate is also detailedly studied. Micro-forming simulation results show that relative punch radius r/t (punch radius r, sheet thickness t) and the ration of the width of coolant channel to channel depth w/h (width of coolant channel w, channel depth h) are import factors that decide the final formability of the whole polar plate. Large r/t is recommended for compact flow channel design and larger w/t is recommended for safer forming process.

Topology Optimization of Blank Geometry for the Sheet Forming Process

2012 ◽  
Author(s):  
Saber DorMohammadi ◽  
Mohammad Rouhi ◽  
Masoud Rais-Rohani
Keyword(s):  
Topology Optimization ◽  
Volume Fraction ◽  
Structural Response ◽  
Sheet Forming ◽  
Forming Process ◽  
Exchange Method ◽  
Forming Simulation ◽  
Blank Shape Optimization ◽  
Blank Shape ◽  
Consistent Subset

The newly developed element exchange method (EEM) for topology optimization is applied to the problem of blank shape optimization for the sheet-forming process. EEM uses a series of stochastic operations guided by the structural response of the model to switch solid and void elements in a given domain to minimize the objective function while maintaining the specified volume fraction. In application of EEM to blank optimization, a sheet forming simulation model is developed using Abaqus/Explicit. With the goal of minimizing the variability in wall thickness of the formed component, a subset of solid (i.e., high density) elements with the highest increase in thickness is exchanged with a consistent subset of void (i.e., low density) elements having the highest decrease in thickness so that the volume fraction remains constant. The EEM operations coupled with finite element simulations are repeated until the optimum blank geometry (i.e., boundary and initial thickness) is found. The developed numerical framework is applied to blank optimization of a benchmark problem. The results show that EEM is successful in generating the optimum blank geometry efficiently and accurately.

Dieless Water Jet Incremental Micro-Forming

2018 ◽  
Author(s):  
Yi Shi ◽  
Jian Cao ◽  
Kornel F. Ehmann
Keyword(s):  
Process Parameters ◽  
Thin Shell ◽  
High Speed ◽  
Single Point ◽  
Sheet Thickness ◽  
Water Jet ◽  
Micro Forming ◽  
Forming Process ◽  
Thin Foils ◽  
High Pressure Water Jet

Compared to the conventional single-point incremental forming (SPIF) processes, water jet incremental micro-forming (WJIMF) utilizes a high-speed and high-pressure water jet as a tool instead of a rigid round-tipped tool to fabricate thin shell micro objects. Thin foils were incrementally formed with micro-scale water jets on a specially designed testbed. In this paper, the effects on the water jet incremental micro-forming process with respect to several key process parameters, including water jet pressure, relative water jet diameter, sheet thickness, and feed rate, were experimentally studied using stainless steel foils. Experimental results indicate that feature geometry, especially depth, can be controlled by adjusting the processes parameters. The presented results and conclusions provide a foundation for future modeling work and the selection of process parameters to achieve high quality thin shell micro products.

scholarly journals High productivity micro rotary swaging

2018 ◽  
Vol 190 ◽  
pp. 15002 ◽  
Author(s):  
Eric Moumi ◽  
Marius Herrmann ◽  
Christian Schenck ◽  
Bernd Kuhfuss
Keyword(s):  
Material Flow ◽  
Process Variations ◽  
Main Process ◽  
Forming Process ◽  
Workpiece Material ◽  
High Productivity ◽  
Rotary Swaging ◽  
Micro Parts ◽  
Intensive Investigation ◽  
Clamping Device

Rotary swaging is an incremental forming process with two main process variations plunge and infeed rotary swaging. With plunge rotary swaging, the diameter is reduced within a limited section whereas the infeed rotary swaging enables a diameter reduction over the entire workpiece length. The process is now subject to intensive investigation for manufacturing of micro parts. By increasing the process speed, failures occur particularly due to inappropriate material flow. In plunge rotary swaging, the workpiece material can flow radially into the gap between the dies and thus the workpiece quality suffers. In infeed rotary swaging the workpiece material flows against the feeding direction and can provoke bending or braking of the workpiece. Therefore, additional measures to control both the radial and the axial material flow to enable high productivity micro rotary swaging are investigated. The radial material flow during plunge rotary swaging can be controlled by elastic intermediate elements that enable an increase of productivity by factor three. A spring-loaded clamping device that enables an increase of the productivity by factor four can temporarily buffer the axial material flow in infeed rotary swaging against the feeding direction.

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