Abstract: Torsion-beam semi-independent suspension represents one of the mainstream applications for passenger-car rear suspensions. The torsion-beam body bears combined bending-and torsion loads during vehicle operation under severe service conditions, and directly determines chassis performance and driving safety. Taking the torsion-beam rear suspension of a certain vehicle as the research object, this paper establishes a rigid-flexible coupled multi-body dynamics model to complete the K&C dynamic performance analysis of the suspension. Working-condition loads are extracted based on the multi-body dynamics model to carry out structural strength and modal computer-aided engineering (CAE) simulation evaluation for the torsion beam. With the equivalent beam model and Morphing shape-optimization method, this paper investigates the influence laws of torsion-beam design parameters on suspension K&C characteristics and structural strength. The results show that for the K&C roll-steer performance, increasing the opening angle of the torsion beam, changing the opening direction from forward to downward, moving forward the mounting position of components, optimizing the bending form of members and extending the length of the middle V-shaped section can effectively improve the roll-steer effect. Under the alternate wheel-hop strength condition of ±30 mm, increasing the contour dimension of the end-section relieves stress concentration, and structural performance exhibits high sensitivity to the wall-thickness parameter of the torsion beam under all strength conditions.

Key words: torsion beam; rigid-flexible coupled multi-body dynamics; K&C; CAE; alternate wheelhop

摘要： 扭力梁半独立悬架是乘用车后悬架主流应用形式，扭力梁本体在车辆行驶中承受弯扭 复合载荷，服役工况严苛，直接决定底盘性能与行车安全。文章以某车型扭力梁后悬架为研 究载体，搭建刚柔耦合多体动力学模型，完成悬架 K&C 动力学性能分析。基于多体动力学模 型提取工况载荷，开展扭力梁结构强度与模态计算机辅助工程（CAE）仿真评估。依托等效 梁模型与 Morphing 形状优化方法，探究扭力梁设计参数对悬架 K&C 特性及结构强度的影响 规律。研究结果表明，对于 K&C 侧倾转向性能，增大扭力梁开口角度、将开口朝前调整为朝 下、前移零件安装位置、优化构件弯曲形态及延长中部 V 形段长度，均可有效改善侧倾转向 效果。在±30 mm 交替轮跳强度工况下，加长端部截面轮廓尺寸可缓解应力集中，且各强度工 况下结构性能对扭力梁壁厚参数敏感度较高。

关键词: 扭力梁；刚柔耦合多体动力学；K&C；CAE；交替轮跳