Study of Vibration Strength of D16 Aluminum Alloy Joints Welded Applying Resistance Spot Welding

Abstract

Purpose of research is to develop and test a technique and perform an experimental study of the vibration strength of D16 aluminum alloy joints welded applying resistance spot welding.Methods. Test coupons were made from 1 mm thick D16 aluminum alloy sheet blanks applying resistance spot welding. A feature of the proposed test is the implementation of a symmetrical loading cycle. During the tests, the number of cycles to failure depending on the range of vibrations was recorded. Annealing and thermomechanical straightening were carried out to exclude helical bending after cutout. After deburring and root facing, the surface of the coupons was prepared for welding using chemical etching. The coupons were welded using a TECNA 8214N spot welding machine. The welding current was 30 kA, the welding duration was 0.1 s, the electrodes force was 180 daN. The static shear strength of the welded joint was studied using a UTS 110M-5 1-U tensile testing machine. The breaking force was 3.66 kN. The peculiarity of the proposed test is the implementation of a symmetrical loading cycle. During the tests, the number of cycles to failure depending on the range of vibrations was recorded.Results. As a result of the statistical analysis of the study results, a linear mathematical relationship between the logarithms of the number of cycles to failure and the amplitude of vibrations was obtained. Depending on the range of vibrations, characteristic zones of destruction were revealed. To provide the possibility of comparing the results of vibration obtained under different conditions of fixing the samples, it is proposed to use the range of vibration displacement per unit length of the work[iece as the ordinate.Conclusion. A technique or studying the vibrational strength of joints welded by resistance spot welding under conditions of a symmetrical loading cycle is proposed and tested. For the studied coupons, the equality of the welded joint to the base metal is achieved at the value of the logarithm of the ratio of the range of vibration displacement per unit length of the coupons equal to 0.01.