Investigation on the Numerical Simulation of Hot Stamping of Advanced High Strength Steels

2011 ◽  
Vol 189-193 ◽  
pp. 2144-2147 ◽  
Author(s):  
Li Min Wang ◽  
Tian Rui Zhou ◽  
Li Juan Wang ◽  
Xiao Ling Yang

Hot stamping represents an innovative manufacturing process for forming of advanced high strength steels, implying a sheet at austenite temperature being rapidly cooled down and formed into a die at the same time (quenching). This affords the opportunity to manufacture components with complex geometric shapes, high strength and a minimum of springback which currently find applications as crash relevant components in the automotive industry. With regard to the numerical modeling of the process, the knowledge of thermal and thermo-mechanical properties of the material is required. The material model under hot stamping condition of advanced high strength steel should be set up. The Finite Element Analysis is an essential precondition for a good process design including all process parameters. This paper presents the finite element simulation of a hot stamping process and describes a number of procedures for the simulation of hot stamping. In addition, the development direction is pointed out at the end of this paper.

Author(s):  
Suleyman Kilic ◽  
Fahrettin Ozturk

Automotive manufacturers always seek high strength and high formability materials for automotive bodies. Advanced high strength steels (AHSS) are excellent candidates for this purpose. These steels generally show a reasonable degree of formability, in addition to their high strength. One particular type is the twinning-induced plasticity (TWIP) steel, which is a high manganese austenite steel, and represents a second generation in AHSS. In this study, comprehensive deformation analysis of TWIP900CR steel including tensile, bending, Erichsen, and deep drawing of cylindrical cups tests is made. Finite element simulation of U and V shaped bending processes is also performed. Results indicate that the TWIP steel has good mechanical properties and high formability. However, springback is quite significant. The coining force should be considered in order to reduce the amount of springback. For springback prediction, it is found that the Yld2000-2d material model has better prediction capability than the Hill48 model.


2020 ◽  
Vol 1009 ◽  
pp. 95-100
Author(s):  
Siam Thongnak ◽  
Tanongsak Yingnakorn ◽  
Loeslakkhana Sriklang ◽  
Sakhob Khumkoa

Advanced High-strength steels (AHSS) has widely application in automotive due to their high tensile strength and remarkable ductility. These good mechanical performances are strongly influenced by the processing and final microstructure. This paper performed Deformation Dilatometer and finite element simulation to study the effect of hot rolling parameters such as strain, cooling rate, and holding time at constant temperature on the microstructure formation of Nb-V low carbon microalloyed steel grade. It found that increasing deformation degree increased the volume fraction of ferrite, both of deformation dilatometer and finite element simulation give a similar trend of effects of hot rolling parameters on evolution of volume fraction of ferrite. These results give an insight for industrial application.


2012 ◽  
Vol 548 ◽  
pp. 456-460 ◽  
Author(s):  
Gopi Alagappan ◽  
Syed H. Masood ◽  
Xuan Zhi Wang

In sheet metal forming, springback is defined as an elastic material recovery after unloading of the forming tools. Springback causes variations and inconsistencies of final part dimensions. Therefore prediction of springback is very important for production of precise products used in automobile and aerospace industries. There are various parameters involved in the process of sheet metal forming, including Young’s modulus, coefficient of friction, Poisson’s ratio, blank thickness, blank length, die radius, punch radius and blank holder force. The aim of this paper is to investigate the springback of a U-channel part by finite element analysis (FEA) and to identify the influences of important parameters on the springback of advanced high strength steels (AHSS) using numerical simulation.


Author(s):  
Saeid Nasheralahkami ◽  
Weitian Zhou ◽  
Sergey Golovashchenko

Advanced high strength steels (AHSS) and ultra-high strength steels (UHSS) have been increasingly implemented by the automotive industry for better crashworthiness and fuel economy. However, these steels are often sensitive to the trimmed edge cracking. The objective of the present paper is to study the sheared edge of ultra-high strength dual-phase steel, DP980, in mechanical trimming and hole punching by sheared edge quality assessment, stretchability, and hole expansion tests as well as finite element analysis. Furthermore, the mechanism of fracture propagation in trimming and hole punching processes of DP980 was discussed. Rather a unique fracture mechanism was observed for trimming of DP980 steel leading to the burr removal at the final stage of the trimming process. Finite element analysis revealed that, under very large clearances, a secondary crack initiates from the edge of the lower tool, and the primary propagated crack turns toward it simultaneously. Intersecting of these two cracks leads to the total separation and leaves the edge of the trimmed part with a broken burr. Fracture observation of trimmed specimens revealed that crack initiation sites under tension moved from the middle of the trimmed surface toward the burr tip with increasing the clearance. This study demonstrates the importance of stretchability tests for designing the stamping dies as well as a reliable finite element simulation for characterizing the material behavior during the shearing process.


Author(s):  
Mohammad Mehdi Kasaei ◽  
Marta C Oliveira

This work presents a new understanding on the deformation mechanics involved in the Nakajima test, which is commonly used to determine the forming limit curve of sheet metals, and is focused on the interaction between the friction conditions and the deformation behaviour of a dual phase steel. The methodology is based on the finite element analysis of the Nakajima test, considering different values of the classic Coulomb friction coefficient, including a pressure-dependent model. The validity of the finite element model is examined through a comparison with experimental data. The results show that friction affects the location and strain path of the necking point by changing the strain rate distribution in the specimen. The strain localization alters the contact status from slip to stick at a portion of the contact area from the pole to the necking zone. This leads to the sharp increase of the strain rate at the necking point, as the punch rises further. The influence of the pressure-dependent friction coefficient on the deformation behaviour is very small, due to the uniform distribution of the contact pressure in the Nakajima test. Moreover, the low contact pressure range attained cannot properly replicate real contact condition in sheet metal forming processes of advanced high strength steels.


2014 ◽  
Vol 1063 ◽  
pp. 334-338 ◽  
Author(s):  
Tzu Hao Hung ◽  
Heng Kuang Tsai ◽  
Fuh Kuo Chen ◽  
Ping Kun Lee

Due to the complexity of hot stamping mechanism, including the coupling of material formability, thermal interaction and metallurgical microstructure, it makes the process design more difficult even with the aid of the finite element analysis. In the present study, the experimental platforms were developed to measure and derive the friction and heat transfer coefficients, respectively. The experiments at various elevated temperatures and contact pressures were conducted and the friction coefficients and heat transfer coefficients were obtained. A finite element model was also established with the experimental data and the material properties of the boron steel calculated from the JMatPro software. The finite element simulations for the hot stamping forming of an automotive door beam, including transportation analysis, hot forming analysis and die quenching analysis were then performed to examine the forming properties of the door beam. The validation of the finite element results by the production part confirms the efficiency and accuracy of the developed experimental platforms and the finite element analysis for the process design of hot stamping.


Sensors ◽  
2021 ◽  
Vol 21 (2) ◽  
pp. 647
Author(s):  
Bo Pang ◽  
Zhongqiu Ji ◽  
Zihua Zhang ◽  
Yunchuan Sun ◽  
Chunmin Ma ◽  
...  

Deep squat, bench press and hard pull are important ways for people to improve their strength. The use of sensors to measure force is rare. Measuring strength with sensors is extremely valuable for people to master the intensity of exercise to scientifically effective exercise. To this end, in this paper, we used a real-time wireless motion capture and mechanical evaluation system of the wearable sensor to measure the dynamic characteristics of 30 young men performing deep squat, bench press and hard pull maneuvers. The data of tibia were simulated with AnyBody 5.2 and ANSYS 19.2 to verify the authenticity. The result demonstrated that the appropriate force of the deep squat elbow joint, the hip joint and the knee joint is 40% 1RM, the appropriate force of the bench press is 40% 1RM and the appropriate force of the hard pull is 80% 1RM. The external force is the main factor of bone change. The mechanical characteristics of knee joint can be simulated after the Finite Element Analysis and the simulation of AnyBody model are verified.


Author(s):  
Arash Khajeh ◽  
Ramin Ebrahimi ◽  
Mohammad Mohsen Moshksar

This study focuses on the finite element analysis of the formation of corner cavity defect during the Backward Cup Extrusion (BCE) process. In the final stage of this process, when the bottom thickness reaches to a critical value this defect will be appear as a circumferential defect in the corner of the cup. In addition, this research examines the temporal prediction of onset of corner cavity formation in the various amounts of the reduction of areas. The finite element simulation results were compared with those of the experimental, indicating that the amount of the reduction of area and that of the friction coefficient have considerable impact on the onset of corner cavity formation during the BCE process.


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