The objective of this paper is to characterize and predict numerically the limits of the holeflan... more The objective of this paper is to characterize and predict numerically the limits of the holeflanging process arising from material failure for two different aluminium sheets. Firstly, an analysis of the types of failure, i.e. necking and cracks, that appear under different process conditions has been performed. Then, a fracture criterion based on local strain measures in tension has been identified for both materials. A particular attention has been paid to the modelling and identification of the constitutive law in a large strain range, and then numerical predictions of the strain limits obtained from successful parts were compared to experimental results. The main conclusions are focused on the occurrence of damage in the conventional hole-flanging process from numerical simulations and experiments, depending on several process parameters.
The effect of the clearance-thickness ratio on the hole-flanging process was investigated to dete... more The effect of the clearance-thickness ratio on the hole-flanging process was investigated to determine the occurrence of ironing. A 2 mm thick 1000 series aluminium alloy sheet was considered. An elasticplastic finite element model using remeshing option was developed. Experiments were conducted to verify the reliability of the developed finite element model. A critical clearance-thickness ratio which is a limit between two conditions of hole-flanging was found: hole-flanging with edge stretching and hole-flanging with ironing in which the metal is squeezed between the punch and the die. The effect of the hole-flanging condition on the punch load, the forming kinematics, the flange geometry and the boring quality was studied. The finite element results were validated by experimental results.
Hole-flanging is a sheet metal forming process which is often used to produce a flange around hol... more Hole-flanging is a sheet metal forming process which is often used to produce a flange around holes. Many industrial applications require a longer flange that can be used for example to increase bearing surface or to increase the number of threads that will fit in a tapped hole. Ironing is usually used during such process to increase the flange height. Due to the thinning of the flange caused by edge stretching, some difficulties arise when trying to set a clearance value for which the process is performed with ironing. Therefore, the occurrence of ironing needs to be more clarified. It is also important to quantify the effect of ironing intensity in the flange geometry. In the present work, FE simulations and experiments are performed to investigate hole-flanging with and without ironing. For this purpose, hole-flanging is carried out by varying the clearance between the punch and the die while keeping constant the other parameters. The aim is to identify the occurrence of ironing by the determination of a limit between the hole-flanging with ironing and the hole-flanging without ironing. Attention is focused on studying the effect of the hole-flanging conditions on the punch load, the forming kinematics and the final shape. The experiments are carried out to check the FE results on an aluminum alloy.
The objective of this paper is to characterize and predict numerically the limits of the holeflan... more The objective of this paper is to characterize and predict numerically the limits of the holeflanging process arising from material failure for two different aluminium sheets. Firstly, an analysis of the types of failure, i.e. necking and cracks, that appear under different process conditions has been performed. Then, a fracture criterion based on local strain measures in tension has been identified for both materials. A particular attention has been paid to the modelling and identification of the constitutive law in a large strain range, and then numerical predictions of the strain limits obtained from successful parts were compared to experimental results. The main conclusions are focused on the occurrence of damage in the conventional hole-flanging process from numerical simulations and experiments, depending on several process parameters.
The effect of the clearance-thickness ratio on the hole-flanging process was investigated to dete... more The effect of the clearance-thickness ratio on the hole-flanging process was investigated to determine the occurrence of ironing. A 2 mm thick 1000 series aluminium alloy sheet was considered. An elasticplastic finite element model using remeshing option was developed. Experiments were conducted to verify the reliability of the developed finite element model. A critical clearance-thickness ratio which is a limit between two conditions of hole-flanging was found: hole-flanging with edge stretching and hole-flanging with ironing in which the metal is squeezed between the punch and the die. The effect of the hole-flanging condition on the punch load, the forming kinematics, the flange geometry and the boring quality was studied. The finite element results were validated by experimental results.
Hole-flanging is a sheet metal forming process which is often used to produce a flange around hol... more Hole-flanging is a sheet metal forming process which is often used to produce a flange around holes. Many industrial applications require a longer flange that can be used for example to increase bearing surface or to increase the number of threads that will fit in a tapped hole. Ironing is usually used during such process to increase the flange height. Due to the thinning of the flange caused by edge stretching, some difficulties arise when trying to set a clearance value for which the process is performed with ironing. Therefore, the occurrence of ironing needs to be more clarified. It is also important to quantify the effect of ironing intensity in the flange geometry. In the present work, FE simulations and experiments are performed to investigate hole-flanging with and without ironing. For this purpose, hole-flanging is carried out by varying the clearance between the punch and the die while keeping constant the other parameters. The aim is to identify the occurrence of ironing by the determination of a limit between the hole-flanging with ironing and the hole-flanging without ironing. Attention is focused on studying the effect of the hole-flanging conditions on the punch load, the forming kinematics and the final shape. The experiments are carried out to check the FE results on an aluminum alloy.
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Papers by Ahmed Kacem