Measurement of residual stress in big weldment and vibraticn stress relieving

This thesis is written for the actual cnginecring work of a big weldment,the boom of 1.6 m backhoc excavator,to improve technology and performance and save energy.The distribution of residual stress of the dangerous sections in the boom has been found.Proper specifications for reducing thc residual stress of the boom by vibration have also becn ascertained.Mcreover,befere vibrating the boom,a preliminary vibration experiment was made on a small test plate.The results show that there is high level residual stress in the boom,and this residual stress can be eliminated by vibration.And so the dimensional stability is improved.Besides,exploratory researches were made on the mechanism of residual stress relieving by vibration and on the relationship between vibration and fatigue.