差厚拼焊管内高压胀形塑性变形规律

PLASTIC DEFORMATION REGULARITY OF TAILOR-WELDED TUBE (TWT) WITH DISSIMILAR THICKNESS DURING HYDRO-BULGING

为揭示差厚拼焊管内高压胀形的变形规律,采用有限元数值模拟和实验并结合力学分析,研究了差厚拼焊管胀形时薄壁管、厚壁管的变形差异,及塑性区的发生、发展过程和促进变形协调的力学和几何因素,分析了差厚变形条件下薄壁管、厚壁管的应力、应变发展历史.结果表明:差厚拼焊管内高压胀形时,厚壁管的变形始终落后于薄壁管.薄壁管中部最先屈服,塑性区自中部向两端逐渐扩展,厚壁管靠近焊缝端先屈服,随着内压升高塑性区逐渐扩展到另一端.变形强化和长度比增大可促进两管协调变形.无论长度比如何变化,整个变形过程中薄壁管轴向应变始终为拉应变,厚壁管轴向始终为压应变.

To reveal the deformation regularity of tailor-welded tube （TWT） with dissimilar thickness during hydro-bugling, finite element analysis （FEA）, experiment and mechanics analysis were conducted on the deformation behaviors of the thinner tube and the thicker tube, the initiation and expanding of the plastic deformation and the factors which affect bulging harmoniously. The effects of dissimilar thickness on the stress and strain history were analyzed. It is indicated that the deformation of thicker tube lags behind the thinner tube during bulging process. For the thinner tube, the plastic zone first occurs at the middle zone, and then expands towards two ends simultaneously.As for the thicker tube, the plastic zone first occurs at the end adjacent to the weld seam, and then expands to another end gradually with the pressure increasing. The deformation compatibility can be improved with increasing the hardening exponent n and the length ratio 7. No matter what the length ratio, the axial strain is tensile strain for the thinner tube. and compress strain for the thicker tube.