Failure Prediction in Sheet Metal Forming Depending in Pre-Straining and Bending Superposition

2012 ◽  
Vol 504-506 ◽  
pp. 101-106 ◽  
Author(s):  
Ralf Denninger ◽  
Mathias Liewald ◽  
Manfred Sindel
Keyword(s):  
Automotive Industry ◽  
Material Failure ◽  
Body Parts ◽  
Process Safety ◽  
Surface Cracks ◽  
Reliable Prediction ◽  
Bending Load ◽  
Forming Simulations ◽  
Further Development ◽  
Simulation Systems

The automotive industry nowadays, uses numerical simulation systems to determine process safety of car body parts. Forming simulations are usually used to predict local necking and cracks during the deep-drawing operation or to calculate the spring-back behaviour. Furthermore, FEA is also used for optimizing the hemming process. In this contribution, further development and the use of an enhanced failure criterion for the evaluation of flanging and hemming processes are shown. This criterion describes material failure caused by incipient surface cracks on the bending edge keeping the predominant bending load conditions in consideration. The investigations of the bending conditions in this criterion include loads from previous forming operations and geometrical aspects, such as bending radii. The approach presented in this contribution can deliver a more reliable prediction regarding the expected material failure.

The Description of Precision Forging Technology in Closed Die of Mg Alloy AZ31 Using Computer Simulation

2014 ◽  
Vol 686 ◽  
pp. 78-81 ◽  
Author(s):  
Mária Kapustová ◽  
Jozef Bílik
Keyword(s):  
Automotive Industry ◽  
Primary Objective ◽  
Pollutant Emissions ◽  
Dominant Position ◽  
Bulk Forming ◽  
Precision Forging ◽  
Die Forging ◽  
Numeric Simulation ◽  
Alloy Type ◽  
Further Development

Automotive industry is nowadays constantly strengthening its dominant position. Its primary objective is to reduce weight of automobiles in order to decrease fuel consumption and amount of harmful pollutant emissions. From the viewpoint of further development in the field of automotive industry, very interesting are the issues of die forgings production from light non-ferrous metals. This article describes research of precision die forging technology in closed die with regard to magnesium alloy type AZ 31. Given alloy type Mg-Al-Zn is suitable for bulk forming and is characterized by good formability at hot conditions. Results of this research may be applied to production of forgings with longitudinal shape, e.g. levers and connecting rods. In order to verify the design of forging technology in closed die for lever-shaped forged piece the simulation program MSC.SuperForge was used. Numeric simulation of die forging process confirmed suitable designed shape and dimensions of semi product and also correct material plastic flow in cavity of closed die.

Study of Damage Limit for Aluminum Alloy Plates with Surface Cracks under Cross-Thickness Bending

2014 ◽  
Vol 881-883 ◽  
pp. 1365-1369
Author(s):  
Hai Yang Yuan ◽  
Yun Xin Wu ◽  
Zhong Huai Wu ◽  
Zhi Qi Liao
Keyword(s):  
Aluminum Alloy ◽  
7075 Aluminum Alloy ◽  
Surface Cracks ◽  
Test Results ◽  
Entire Cross Section ◽  
Reference Stress ◽  
Bending Load ◽  
Shallow Crack ◽  
Deep Crack ◽  
Good Agreement

A damage limit prediction model was built due to fracture failure problems of aluminum alloy plates. Based on the global plastic collapse of the entire cross-section containing the defect, the relationships of crack width and depth of fracturing 7075 aluminum alloy plates with either shallow crack or deep crack was analyzed by using reference stress method. The damage limit curves of 7075 aluminum alloy plates with crack was drew, and safety zone of crack propagation under corresponding bending load was confirmed. Then the experimental verification was carried out, results show that calculated results are in good agreement with the test results during the shallow crack stage, while in the deep crack stage experimental results are slightly less than calculated results.

Growth Behavior of Two Interacting Surface Cracks of Dissimilar Size (Comparison for Tensile and Bending Load)

2010 ◽  
Author(s):  
Masayuki Kamaya ◽  
Masanori Kikuchi ◽  
Eiichi Miyokawa
Keyword(s):  
Finite Element ◽  
Element Model ◽  
Growth Behavior ◽  
Multiple Cracks ◽  
Surface Cracks ◽  
Element Mesh ◽  
Loading Direction ◽  
Parallel Surface ◽  
Bending Load ◽  
The Difference

When multiple cracks approach one another, the stress intensity factor is likely to change due to the interaction of the stress field. This causes change in growth rate and shape of cracks. In particular, when cracks are in parallel position to the loading direction, the shape of cracks becomes non-planar. In this study, the complex growth of interacting cracks is evaluated by using the S-Version finite element method, in which local detailed finite element mesh (local mesh) is superposed on cores finite element model (global mesh) representing the global structure. In this study, two parallel surface cracks are subjected to two types of loading; tensile and bending load. Comparisons are made on the growth behavior under two types of loading. It is shown that the smaller crack stop growing due to the interaction when the difference in size of two cracks is large. This tendency is more significant for the bending load. The procedure for evaluating crack growth for Fitness-for-Service assessment is discussed.

A Criterion for Combination Rule in Flaw Assessment of Parallel Surface Cracks

2011 ◽  
Vol 133 (6) ◽  
Author(s):  
Masayuki Kamaya
Keyword(s):  
Stress Intensity ◽  
Structural Reliability ◽  
Crack Depth ◽  
Crack Size ◽  
Multiple Cracks ◽  
J Integral ◽  
Surface Cracks ◽  
Linear Elastic ◽  
Offset Distance ◽  
Bending Load

When multiple cracks approach one another, the stress intensity factor and J-integral value change due to the interaction of the stress field. Since the changes in these parameters are not always conservative in structural reliability evaluations, the interaction between multiple cracks should be taken into account. Section XI of the ASME Boiler and Pressure Vessel Code provides a flaw characterization rule for interacting multiple cracks. In Section XI, adjacent cracks are replaced with a coalesced single crack when the distance between the cracks is less than half of the crack depth. However, the criterion for the offset distance is given as an absolute value, although the magnitude of the interaction depends on the crack size. In the current study, an alternative criterion for the offset distance was examined. Linear-elastic and elastic–plastic analyses were performed for interacting semicircular and semi-elliptical surface cracks by the finite element method under a tensile or bending load. The change in the stress intensity factors and J-integral values due to the relative spacing of cracks was investigated. Based on the relationship between the magnitude of the interaction and the relative position of the cracks, the allowable ctriterion for the offset distance was discussed.

scholarly journals Smart Process Combination for Aluminum/Plastic Hybrid Components

2018 ◽  
Vol 1 (2) ◽  
Author(s):  
André Albert ◽  
Wolfgang Zorn ◽  
Markus Layer ◽  
Welf-Guntram Drossel ◽  
Dirk Landgrebe ◽  
...  
Keyword(s):  
Automotive Industry ◽  
Body Parts ◽  
Production Engineering ◽  
Lightweight Construction ◽  
Lightweight Structures ◽  
Car Body ◽  
State Of Research ◽  
The One ◽  
Integrated Or ◽  
Process Combination

The research on lightweight construction increasingly gains in importance, especially for the automotive industry. New lightweight components ensure the necessary stability of car body parts on the one hand. On the other hand they are supposed to allow a low priced production. Hence, aluminum or magnesium alloys have quite a large share in production engineering. During the last years, research mainly addressed metal/plastic compounds. Weight reduction as well as the capability of producing complex structures are only some of the benefits of this technology. Furthermore, additional functionality can be integrated or functional tasks can be distributed: The metal ensures stiffness and realizes the technical connection to the car body by means of welding, while the plastic enables the insertion of special elements for the joining or assembly process. This paper presents two approaches of realizing a combined process to produce aluminum/plastic-hybrid structures. In a first approach, an active tool is presented to realize the sheet based process. The second approach focusses on the tube-based process and presents the topical state of research within the Federal Cluster of Excellence EXC 1075 “Merge Technologies for Multifunctional Lightweight Structures”.

scholarly journals ABOUT THE GLOBAL ENVIRONMENTAL CRISIS MOTOR VEHICLES AND THE STATE OF THE TRANSPORT-ROAD COMPLEX OF THE RUSSIAN FEDERATION

2018 ◽  
Vol 1 (12) ◽  
pp. 202-206
Author(s):  
Anna Berezina ◽  
Yuriy Katul'skiy
Keyword(s):  
Russian Federation ◽  
Automotive Industry ◽  
The State ◽  
Environmental Crisis ◽  
Motor Vehicles ◽  
Global Environmental ◽  
The World ◽  
Car Park ◽  
The Russian Federation ◽  
Further Development

This article provides an overview of legislation in the field of regulation of emissions on the world stage, presents the data of the car Park of the Russian Federation. The analysis of the further development of the automotive industry.

scholarly journals A Damage Tolerance Model for Plates with Surface Cracks Under Combined End Force and Bending

2014 ◽  
Vol 8 (1) ◽  
pp. 562-566
Author(s):  
Yuan Haiyang ◽  
Wu Yunxin ◽  
Liao Zhiqi
Keyword(s):  
Mathematical Model ◽  
Aluminum Alloy ◽  
Damage Tolerance ◽  
Surface Cracks ◽  
Critical Crack ◽  
Reference Stress ◽  
Bending Load ◽  
Bending Loads ◽  
Tolerance Model ◽  
Shallow Crack

Reference stress statuses and the critical crack sizes are analyzed systematically and in detail for rectangle surface cracks in plates under combined endforce and cross-thickness bending loads via the ‘global’ reference stress method. The relationships of critical crack width and depth are obtained from the critical crack sizes analysis. Based on the net-section plastic collapse of the flawed component, a damage tolerance mathematical model for plates with single crack was built, which did not consider the contact of crack faces and it can be used for plates with a shallow crack or a deep crack under combined endforce and cross-thickness bending load. Using this mathematical model, the damage limits of aluminum alloy plates under different bending loads are obtained and a simplified damage tolerance model for aluminum alloy plates is established via regression analysis. The results obtained from the model and the regression model agree well with the experimental results especially when a/t<0.8. The test results show that the model can be fast and conveniently predict the damage limits for plates with surface cracks under bending.

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