Experiment research on NVH performance of block-head assembly parts of engine

The characteristics of vibration and acoustic radiation of block-head assembly parts of engine were studied by experiments. The effects of assembling method using tap-bolts and through-bolts, and pre-tightening torque were explained through the parameters of nature frequency, damping ration, and sound radiation efficiency. The results show that the through-bolting method contributed higher rigidity and larger damping ratio compared to the tap-bolting case. through-bolting has benefit to reduce the vibration of assemblies. Larger bolt pre-tightening torque can reduce the damping ratio of assemblies. Assembling method and pre-tightening torque has slightly influence on the sound radiation efficiency of cylinder block