Finite Element Analysis of Asymmetrical Leg-length in Closed U-bending Process

Author(s):  
Sutasn Thipprakmas ◽  
Untika Boochakul ◽  
Wiriyakorn Phanitwong
Author(s):  
N. F. Othman ◽  
H. Y. Tan ◽  
K. S. Basaruddin ◽  
M. H. Mat Som ◽  
W. M. R. Rusli ◽  
...  

Leg length inequality, also known as leg length discrepancy (LLD) is a condition which the left and right legs of an individual are noticeably different in length. When the level of LLD is high, such as those of 20 mm and above, it would disturb the wellbeing of an individual in terms of gait, and also causes them to experience higher stress in their pelvis compared to individual without LLD. In order to study load due to LLD had affects human bones such as the pelvic bone, finite element analysis (FEA) approach is usually used as it allows limitless attempt to investigate the stress-strain response on human bones and is far more practical than experimenting on real bones, therefore FEA was done with by using ANSYS 15.0. From the data obtained via FEA, the risk of fracture can be calculated, which gives us an insight on how would LLD affects the risk of bone fracture. In this study the effect of pelvic tilt caused by LLD has been studied, along with how loads at various LLD level affects the pelvic bone. The verdict from the study is the pelvic tilt caused by LLD amplifies the maximum stress and strain on the pelvic bone. The analysis using hip load due to LLD shows a downtrend for the maximum stress caused by the longer limb as the level of LLD increases, while the maximum stress caused by the shorter limb shows an uptrend with the increment of LLD. The maximum stress and strain observed are usually distributed around the sacroiliac joint. It is also observed that the higher the level of LLD is, the higher the maximum stress on pelvic bone will become, hence the higher the fracture risk.


2010 ◽  
Author(s):  
Z. J. Li ◽  
H. Yang ◽  
F. Barlat ◽  
Y. H. Moon ◽  
M. G. Lee

2013 ◽  
Vol 423-426 ◽  
pp. 978-983
Author(s):  
Xie Li

Springback is a common phenomenon in air bending of sheet metal forming, caused by the elastic redistribution of the internal stresses during unloading. It has been recognized that springback is essential for the design of the air bending. Traditionally, the values of springback is obtained for air bending parameters from handbook tables or springback graphs. However, the handbook tables or springback graphs are obtained using experiments and it is a time consuming processes. In this paper, a finite element model has been used to analyze the air bending process. Some experiments are carried out on ST12 materials, and the finite element model is validated comparing with experiments. In the present research the influence of process variables such as punch radius, die radius and die on springback are discussed using finite element analysis. Thus, the presented results of this research provide a basis of design to improve forming quality.


2014 ◽  
Vol 900 ◽  
pp. 561-564 ◽  
Author(s):  
Xiao Bing Dang ◽  
Kai He ◽  
Shu Guo Wei ◽  
Jiu Hua Li ◽  
Ru Xu Du

Based on the thought of incremental forming, a new kind of sheet metal bending process has been described and investigated in this article. The software of the control system for the specific machine is developed combining motion control card and servo motors. Both single point and multi-points bending are taken into consideration from experimental and finite element analysis. Curved sheet and hyperbolic sheet metal are examined through experiments to extend the application for more smoothed and complicated curved sheet metal. The effectiveness of the process to deal with complex curved sheet metal is shown by all the experiments.


2015 ◽  
Vol 651-653 ◽  
pp. 1090-1095 ◽  
Author(s):  
Vitalii Vorkov ◽  
Richard Aerens ◽  
Dirk Vandepitte ◽  
Joost R. Duflou

Bump bending or step bending is a forming technique that allows making large radius bends in a sheet metal part by means of a series of bends performed close to each other. The bump bending process has been studied by means of both an experimental campaign and finite element analysis. High-strength steel Weldox 1300 and a punch of radius 30 mm have been used. The finite element calculations have been performed with Abaqus using the solid formulation and Implicit/Explicit solvers. The results of the finite element analysis have been validated experimentally by monitoring the bending process using a camera system aligned with the bending line. Experiments were performed on a press-brake with a capacity of 50 metric tons. Deflections of a sheet during and after bending have been measured using the images recorded by the camera. In order to investigate the influence of a new bend on a previously formed bend, experiments have been performed with different distances between two consecutive bends. Based on the experiments, the size of the affected zone for the bend has been measured. The dependence of the distance between two consecutive bends on the resulting global bending angle has been studied. Moreover the influence of the bump distance on the springback has been investigated.


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