Electrical contact crimping is a mechanical fastening process commonly used in aeronautical and aero spatial applications. In order to ensure the perfect electrical conduction and acceptable mechanical properties, the assembly have to fullfil some drastic holding force criteria. This outfit is directly dependent on the indentation depth at the end of crimping. The feedback generally reveals that an over crimping will lead to the cable breakage whereas an under crimping will be characterized by the cable sliding into the contact during pulling. The optimal behavior is a combinaison of both phenomena : the cable must become thinner before slipping into the contact. Numerical simulation is an efficient tool to limit the tedious experimental tests. It is the main topic of our work. This paper deals with prediction of the failure type and the force level required to tear out a contact crimped on multistrand cable for different indentation depths. The determination of optimal crimping condition is determined. In order to simulate the contact tensile test, crimping simulation has to be performed. The first step is then to be able to simulate accurately the crimping stage by using appropriate behavior laws and realistic conditions. One difficulty is linked to the small size of our objects. The first one is a 19 strands cable, in which each strand is about 0.15 mm diameter. The second sample is a 1 mm diameter cylindrical copper contact measuring 7 mm long. Adapted testing devices are described. Geometries and mechanical fields are obtained and then exported in the mechanical holding model to ensure realistic prediction [1]. Impact of crimping conditions on the pulling results is discussed. Pulling simulation results are compared to experimental values. The prediction of breakage mechanisms is also studied. Keywords: Crimping process, mechanical fastening operation, finite element computations, mechanical strength, breakout force, tensile test. [1] Fayolle, S., 2008, Etude de la modélisation de la pose et de la tenue mécanique des assemblages par déformation plastique : application au rivetage auto poinçonneur, Thèse de l'Ecole des Mines de Paris.

Several thousands electrical connections are necessary in airplanes. Electrical cables are joined to contacts using manual crimping devices in industrial plants. When mechanical defects appear, the replacement of the defective connections has to be made directly on the airplane. This operation is difficult and time-consuming due to reduced accessibility, making it very costly. The aim of this paper is to simulate the crimping operation and then evaluate the mechanical strength of the obtained connection -in order to identify, understand and eliminate defects due to unsatisfactory crimping operations. Material behavior data is accessed through mechanical testing performed on cables and contact; accurate material data is mandatory to improve the accuracy of the simulation results.The Forge® software is used to perform the numerical simulation to predict the stress and strain distribution as well as the crimping force during crimping operations. Resulting mechanical strength of the joint is also analysed using numerical simulation. Experimental and numerical results are then compared.

International audienceThis work focuses on the modeling of the aeronautical electrical contact crimping process for aircraft applications. Several thousands of crimped contact can be found in an airplane or a helicopter. The crimping process has thus to be mastered precisely in order to avoid expensive repairing and dangerous configurations. Electrical crimping is a plastic deformation process of a contact (component) on a multi-strand wire. All components are highly deformed in order to impose mechanical contact and electrical continuity. The components are very small for the cases studied in this work (0.12 mm diameter wire or 1 mm diameter cylinders). The work has been divided in 3 main steps. First, material characterization is performed in order to identify behavior laws to feed numerical simulations. The challenge is to be able to deal with very small components. The second point is to build an accurate a numerical model of the crimping process. The numerical model is compared with experimental results. Validation is done comparing with both laboratory devices and real crimped assemblies. Finally mechanical strength is studied. The numerical model is used to verify the impact of components’ dimensions or crimping condition on the mechanical resistance. Numerical models are also compared to experimental data