Incorporation of Sheet-Forming Effects in Crash Simulations Using Ideal Forming Theory and Hybrid Membrane and Shell Method

2005 ◽  
Vol 127 (1) ◽  
pp. 182-192 ◽  
Author(s):  
Hansun Ryou ◽  
Kwansoo Chung ◽  
Jeong-Whan Yoon ◽  
Chung-Souk Han ◽  
Jae Ryoun Youn ◽  
...  
Keyword(s):  
Kinematic Hardening ◽  
Three Dimensional ◽  
Computation Time ◽  
Cost Effective ◽  
Sheet Forming ◽  
Hybrid Membrane ◽  
Forming Process ◽  
Explicit Finite Element ◽  
Hardening Law ◽  
Process Effects

In order to achieve reliable but cost-effective crash simulations of stamped parts, sheet-forming process effects were incorporated in simulations using the ideal forming theory mixed with the three-dimensional hybrid membrane and shell method, while the subsequent crash simulations were carried out using a dynamic explicit finite element code. Example solutions performed for forming and crash simulations of I- and S-shaped rails verified that the proposed approach is cost effective without sacrificing accuracy. The method required a significantly small amount of additional computation time, less than 3% for the specific examples, to incorporate sheet-forming effects into crash simulations. As for the constitutive equation, the combined isotropic-kinematic hardening law and the nonquadratic anisotropic yield stress potential as well as its conjugate strain-rate potential were used to describe the anisotropy of AA6111-T4 aluminum alloy sheets.

Concurrent Engineering Design of Sheet Stamping by Using an Inverse FE Approach

1997 ◽  
Author(s):  
Shiyong Yang ◽  
Kikuo Nezu
Keyword(s):  
Finite Element ◽  
Concurrent Engineering ◽  
Process Simulation ◽  
Three Dimensional ◽  
Sheet Forming ◽  
Design Stage ◽  
Forming Process ◽  
Element Analysis ◽  
Preliminary Design Stage ◽  
Product And Process

Abstract An inverse finite element (FE) algorithm is proposed for sheet forming process simulation. With the inverse finite element analysis (FEA) program developed, a new method for concurrent engineering (CE) design for sheet metal forming product and process is proposed. After the product geometry is defined by using parametric patches, the input models for process simulation can be created without the necessity to define the initial blank and the geometry of tools, thus simplifying the design process and facilitating the designer to look into the formability and quality of the product being designed at preliminary design stage. With resort to a commercially available software, P3/PATRAN, arbitrarily three-dimensional product can be designed for manufacturability for sheet forming process by following the procedures given.

scholarly journals Thickness control in a new flexible hybrid incremental sheet forming process

2017 ◽  
Vol 231 (5) ◽  
pp. 779-791 ◽  
Author(s):  
Huan Zhang ◽  
Bin Lu ◽  
Jun Chen ◽  
Sule Feng ◽  
Zongquan Li ◽  
...  
Keyword(s):  
Production Efficiency ◽  
Thickness Distribution ◽  
Sheet Thickness ◽  
Cost Effective ◽  
Sheet Forming ◽  
Incremental Sheet Forming ◽  
Optimization Approach ◽  
Forming Process ◽  
Thickness Prediction ◽  
Flexible Forming Process

Incremental sheet forming is a cost-effective process for rapid manufacturing of sheet metal products. However, incremental sheet forming also has some limitations such as severe sheet thinning and long processing time. These limitations hamper the forming part quality and production efficiency, thus restricting the incremental sheet forming application in industrial practice. To overcome the problem of sheet thinning, a variety of processes, such as multi-step incremental sheet forming, have been proposed to improve the material flow and thickness distribution. In this work, a new process has been developed by introducing multi-point forming as preforming step before conducting incremental sheet forming processing. Employing an established hybrid sheet forming system and the corresponding thickness prediction model, the preform shape can be optimized by employing a two-step optimization approach to improve the sheet thickness distribution. In total, two case study examples, including a hemisphere part and an aerospace cowling part, are fabricated using the developed hybrid flexible process in this study. The experimental results show that the hybrid flexible forming process with the optimal preform design could achieve sheet parts with more uniform thickness distribution and reduced forming time.

Numerical Simulation and Experiment Research on Surface Defects for Thick Plate Multi-Point Forming Process

2013 ◽  
Vol 385-386 ◽  
pp. 59-62
Author(s):  
Le Li ◽  
Li Yong Wang
Keyword(s):  
Flexible Manufacturing ◽  
Surface Defects ◽  
Three Dimensional ◽  
Metal Plate ◽  
Curvature Radius ◽  
Forming Process ◽  
Explicit Finite Element ◽  
Deformation Features ◽  
Simulation And Experiment ◽  
Forming Defects

Multi-point forming (MPF) is an advanced flexible manufacturing technology for three-dimensional sheet metal forming. The substance of MPF is replacing the conventional solid dies by a set of discrete punches called punch group. Due to the discrete contacts between the workpiece and punches, the dimple defects occurred, which are inevitable and particular for MPF. In this study, the analysis of the deformation features of the dimple defects was implemented. The dynamic explicit finite element method was chosen to implement the simulation of MPF process. The influencing factors of the surface defects were researched. The relevant experiment was implemented, and it verified that the forming defects decreased with the increasing of the thickness of metal plate and the objective surface curvature radius.

Spring-Back Evaluation of Stretch Bending Process Based on Chaboche Combined Isotropic-Kinematic Hardening Laws

2011 ◽  
Vol 204-210 ◽  
pp. 1745-1750 ◽  
Author(s):  
Jing Hu ◽  
Xiao Xing Li ◽  
Kwan Soo Chung ◽  
Rao Yao
Keyword(s):  
Kinematic Hardening ◽  
Spring Back ◽  
Stretch Forming ◽  
Forming Process ◽  
Hardening Law ◽  
Stretch Bending ◽  
User Subroutine ◽  
Bending Process ◽  
Chaboche Model ◽  
Simulation Results

We present a study on spring-back prediction in the stretching bending process using the Chaboche model combined isotropic-kinematic hardening law and Mises yielding criterion, and a material user subroutine (VUMAT, UMAT) program was developed base on the ABAQUS interface for the model. The effects of different hardening law on the spring-back in the stretch forming process was also analyzed and compared. The simulation results show that the combined isotropic-kinematic hardening law has the better spring-back prediction compared with the pure isotropic and kinematic hardening law in the stretch forming process, which is verified by the experimental results.

Investigation on Wrinkling Deformation in Multi-Pass Incremental Sheet Forming Process

2016 ◽  
Vol 725 ◽  
pp. 578-585 ◽  
Author(s):  
Zhao Bing Liu ◽  
Paul Anthony Meehan
Keyword(s):  
Thickness Distribution ◽  
Three Dimensional ◽  
Experimental Tests ◽  
Sheet Forming ◽  
Incremental Sheet Forming ◽  
Final Part ◽  
Optimized Design ◽  
Forming Process ◽  
Element Analysis ◽  
Form Complex

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.

Choice of Objective Rate for Non-Proportional Loading Applications

2004 ◽  
Author(s):  
R. G. Sauve´
Keyword(s):  
Finite Deformation ◽  
Kinematic Hardening ◽  
Three Dimensional ◽  
Large Strains ◽  
Biaxial Testing ◽  
Proportional Loading ◽  
Hardening Law ◽  
Thin Tube ◽  
Deformation Plasticity ◽  
Objective Rate

Traditionally, the validation of three dimensional constitutive formulations (i.e. theories of plasticity) has been carried out using biaxial testing. The most widely used method for biaxial testing is the combined tension-torsion loading of thin-walled cylindrical specimens. Unfortunately, the results obtained in the past, using the incremental theory to model tension-torsion experiments involving large strains and non-proportional loading paths, are not always in agreement with observations. Two possible sources of error lie in: (i) the particular objective rate chosen for the constitutive equation, and (ii) the kinematic hardening model used to account for material anisotropy. In this study, it is demonstrated that an appropriate choice of objective stress rate can lead to improved correlation between analytical and experimental results even with the use of a simple kinematic hardening law. The evaluation is carried out using non-proportional tension-torsion loading of a thin tube. The purpose of this paper is to review the objective E-rate formulation against alternative rate formulations and demonstrate its advantage in problems involving elastic-plastic and non-proportional loading, through the finite deformation solution of tension followed by torsional loading of a thin tube. Details of the analytical thin tube solution of non-proportional tension torsion loading generalized to finite deformation plasticity is presented along with comparison of results to experiments.

Analysis of Forming Process of Automotive Aluminum Alloys Considering Formability and Springback

2007 ◽  
Vol 345-346 ◽  
pp. 857-860 ◽  
Author(s):  
Won Oh Lee ◽  
Dae Yong Kim ◽  
June Hyung Kim ◽  
Kwan Soo Chung ◽  
Seung Hyun Hong
Keyword(s):  
Kinematic Hardening ◽  
Transient Behavior ◽  
Alloy Sheet ◽  
Forming Limit ◽  
Plastic Behavior ◽  
Compression Tests ◽  
Forming Process ◽  
Hardening Law ◽  
Axial Tension ◽  
Tension Tests

Formability and springback of the automotive aluminum alloy sheet, 6K21-T4, in the sheet forming process were numerically investigated utilizing the combined isotropic-kinematic hardening law based on the modified Chaboche model. To account for the anisotropic plastic behavior, the non-quadratic anisotropic yield stress potential, Yld2004-18p was considered. In order to characterize the mechanical properties, uni-axial tension tests were performed for the anisotropic yielding and hardening behavior, while uni-axial tension/compression tests were performed for the Bauschinger and transient behavior. The Erichsen test was carried out to partially obtain forming limit strains and FLD was also calculated based on the M-K theory to complete the FLD. The failure location during simulation was determined by comparing strains with FLD strains. For verification purposes, the automotive hood outer panel was stamped in real. After forming, the amount of draw-in, thinning and springback were measured and compared with numerical simulation results.

Studies on the Springback Mechanism of Incremental Sheet Forming Based on FEM Simulation

2010 ◽  
Vol 102-104 ◽  
pp. 242-246 ◽  
Author(s):  
Fei Han ◽  
Jian Hua Mo ◽  
Xiao Hui Cui ◽  
Zai Lin Wang
Keyword(s):  
Metal Forming ◽  
Three Dimensional ◽  
Fem Simulation ◽  
Element Model ◽  
Sheet Forming ◽  
Incremental Sheet Forming ◽  
Strain History ◽  
Forming Process ◽  
Metal Forming Process

Incremental sheet forming (ISF) is an innovative and highly flexible sheet metal forming process for small batch production and prototyping, but springback is a very important factor to influence the quality of incremental sheet forming. This paper investigates the springback mechanism of incremental sheet forming using numerical method. A three-dimensional elasto-plastic finite element model was established for the simulation of the incremental sheet forming process. In this model, the combination of dynamic explicit algorithm and the static implicit algorithm was proposed to calculate the whole forming process including springback. The results of numerical simulation, such as, the strain history and distribution, the stress state and distribution, etc., are discussed in details. Moreover, the results confirm that residual stress has been releasing during forming process, which reveal the peculiar springback characteristic of incremental sheet forming process.

Three Dimensional Simulation of Air Bleed Duct under Deep Drawing of Ti 6Al-6V-2SN

2015 ◽  
Vol 766-767 ◽  
pp. 1050-1054
Author(s):  
P. Gunasekar
Keyword(s):  
High Pressure ◽  
Deep Drawing ◽  
Three Dimensional ◽  
Extreme Temperature ◽  
Cost Effective ◽  
Maintenance Cost ◽  
Climate Control ◽  
Forming Process ◽  
Long Time ◽  
Dimensional Simulation

Deep drawing is the compression-tension forming process which has been around for a long time. This is a cheap and cost effective process. This paper investigates the manufacturing of the air bleed duct under deep drawing with the velocity of 7 inches/second. Bleed air is compressed air taken from aircraft turbine engines for cabin climate control and systems such as de-icing equipment and also used in after burners. Bleed air duct used to operate the control of air flow to the cabin and powerplant. Bleed air possesses high temperature and high pressure, hence the quality of the duct should be strong enough to withstand them. In general air bleed duct made of titanium alloys under forming process with low strength, which causes the failure and replacement of air bleed duct when they expose to extreme temperature cases. The deep forming process will increase the strength of the bleed duct which reduces the replacement of air duct periodically and reduces the maintenance cost of the aircraft. In addition this paper provides the stress and strain energy data in order to understand the mechanical behavior of titanium alloy when they undergo high pressure blank process.

scholarly journals Practical Cross-Layer Radio Frequency-Based Authentication Scheme for Internet of Things

Sensors ◽  
2021 ◽  
Vol 21 (12) ◽  
pp. 4034
Author(s):  
Arie Haenel ◽  
Yoram Haddad ◽  
Maryline Laurent ◽  
Zonghua Zhang
Keyword(s):  
Internet Of Things ◽  
Radio Frequency ◽  
Real Life ◽  
Computation Time ◽  
Cost Effective ◽  
Battery Life ◽  
Cross Layer ◽  
Security Level ◽  
Cost Of Energy ◽  
Iot Devices

The Internet of Things world is in need of practical solutions for its security. Existing security mechanisms for IoT are mostly not implemented due to complexity, budget, and energy-saving issues. This is especially true for IoT devices that are battery powered, and they should be cost effective to be deployed extensively in the field. In this work, we propose a new cross-layer approach combining existing authentication protocols and existing Physical Layer Radio Frequency Fingerprinting technologies to provide hybrid authentication mechanisms that are practically proved efficient in the field. Even though several Radio Frequency Fingerprinting methods have been proposed so far, as a support for multi-factor authentication or even on their own, practical solutions are still a challenge. The accuracy results achieved with even the best systems using expensive equipment are still not sufficient on real-life systems. Our approach proposes a hybrid protocol that can save energy and computation time on the IoT devices side, proportionally to the accuracy of the Radio Frequency Fingerprinting used, which has a measurable benefit while keeping an acceptable security level. We implemented a full system operating in real time and achieved an accuracy of 99.8% for the additional cost of energy, leading to a decrease of only ~20% in battery life.

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