Automotive connectors in modern car generations are submitted to high current; this can cause many problems and requires the minimization of their electrical contact resistances. The new major contribution of this work is the optimization by finite element method of contact resistance, contact temperature, design, and mechanical stress of sphere/plane contact samples. These contact samples were made with recent high-copper alloys and were subjected to indentation loading. Experimental tests were carried out in order to validate the developed numerical model and to select the material which presents a low contact temperature and contact resistance. Another model with multipoint contacts was developed in order to minimize electrical contact resistance and contact temperature. Shape optimization results indicate that the volume of contact samples was reduced by 12%. The results show also for the model with multipoint contacts that the contact resistance was reduced by 41%, contact temperature by 22% and maximum Von Mises stress by 49%. These several gains are more interesting for the connector designers.

Contact resistance of the copper alloys used in automotive connectors was studied in the literature, but no study has been undertaken in order to optimize this resistance for the new high-copper alloys intended for power automotive connectors.This study was carried out in order to determine the changes in resistance for different loadings and contact geometries. A new generation of high-performance copper alloys was analysed. The used samples were U shaped with a segment containing a sphere and were subjected to insertion (sliding contact) and indentation (static contact) tests. A finite element simulation using the ANSYS code gave contact modellings with or without roughness; this roughness was measured with a profilometer. Numerical modelling of the contact surfaces when the roughness of the materials was taken into account led to results close to the experimental results especially in the case of the lower forces during the indentation test. On the other hand, a relation between the contact resistance and the contact force was established.These results could help in the choice of a material to provide a good compromise concerning both the electrical and the mechanical aspects for a power connector used for automotive industry.

No abstract

The direct metal/metal sliding contact causes a severe wear with a high friction coefficient and an important wear rate. Applying magnetic field into the rotating sliding steel Fe360 B/steel Fe360 B modifies the friction and the wear behavior of the contact. The experimental tests were conducted in three different environments such as: ambient air, pure oxygen at 105 Pa and high vacuum at 5.10−5 Pa. In ambient air and without magnetic field, the metal/metal contact is ductile. When a magnetic field is applied, the formation of oxide layer evolves progressively with the number of sliding cycles. This contact has a low friction and mild wear. Under oxygen, the oxide film appears in wear track with and without applied magnetic field. The wear rate under oxygen is lower than that in ambient air with a ratio roughly equals to 10. In oxygen, the average value of friction coefficient µ decreases from µ = 0.41 to µ = 0.30. In vacuum, the increase of surface hardness causes a transfer of particles from the disc towards the pin. This transfer modifies the morphology of the wear track, increases the surfaces roughness and leads to a strong adhesive wear. The different analysis obtained with: microscopy, micro-harness, wear losses, EDX and friction evolution explains the effect of applied magnetic field on the friction behavior of Fe360 B steel.