Trends in the Development of Machinery and Associated Technology ” TMT 2010 , Mediterranean Cruise , 11-18 September 2010 EXPERIMENTAL DETERMINATION OF FORMING LIMIT DIAGRAM
Forming limit diagrams (FLDs) are a convenient and often used tool for the classification of the formability and for the evaluation of the forming process of sheet materials. Forming limits of sheet metal are represented in the forming limit diagram (FLD) occurring by various deformation states. The paper introduces a experiment method for determination of forming limit curve for whole range of the FLD for sheet metal.
Determination of forming limit diagrams – a new analysis method for characterization of materials' formability
Abstract This paper introduces a new analysis method for characterization of materials' formability independent of individual expertise. Therefore forming limit diagrams (FLDs) are determined using the Nakazima method. Investigations on the influence of the analysis method and the failure criterion in detail will be presented. The new analysis method avoids misinterpretation of the forming limits of any material and the FLD. The forming behavior of materials has to be recorded with a frequency up to 20 Hz, in order to detect the forming limits within a sequence of pictures from onset of necking to failure by cracking.
Analyses of the Forming Limit Diagram in Digital Environment
The determination of the forming limit diagrams (FLDs) for sheet metal can be influenced by testing parameters and a chosen testing procedure. Many different tests have been applied and recent work has resulted in some guidelines to decrease the influence of the testing method and the expertise of an individual laboratory. In the last years some methods have been developed which tend to be independent from the individual expertise, but comprehensive experimental work is still indispensable to obtain the material’s necking and failure limit. The experimental work could be omitted by prediction of the FLD with numerical simulations. The paper presents a methodology to determine the whole area of the FLD for sheet metal in a digital environment. The material thinning has been analysed with the finite element simulation using the ABAQUS program. The Marciniak testing procedure has been chosen to determine the FLD. The thickness strain as a function of time as well as first and second time derivation of the thickness strain have been analysed for the critical specimen areas where the onset and propagation of necking occur.