脉动液压加载方式下金属薄壁管液压成形能力提高机理的研究

Researches in this project are conducted on the plastic hardening, the dynamics frictional characteristics, the micro-structural evolution and the wrinkling development of metal thin-walled tubes in pulsating hydroforming in order to reveal their roles in the improvement of the formability of metal thin-walled tubes in pulsating hydroforming. The researches are focused on the followings. Initially, plastic deformation behavior of metal thin-walled tubes in pulsating hydroforming are investigated and a novel method to determine the plastic hardening model of metal thin-walled tubes is proposed based on the pulsating hydroforming. Second, dynamics frictional characteristics in the pulsating hydroforming is probed and a novel approach to determine the coefficient of friction between tube and die in the guiding zone is presented, as well as the effect of the pulsating internal pressure on the frictional characteristics is evaluated. Afterwards, the influence of the pulsating internal pressure on the microstructure of the tubes is analyzed and the relationships among the formability and the evolution of the microstructure as well as the pulsating parameters are established. Finally, the control and utilization of the wrinkling under the pulsating internal pressure is performed to improve the formability- - after the wrinkling development is examined, the conditions to repeating the appearance and disappearance of small wrinkling is built, a approach to maintain the repeating state is put forward and the impact of the repeating state on the formability is clarified. The research results of the project will lay the theoretical foundation for the pulsating hydroforming and provide scientific basis and technical support for expanding its applied scope.

通过对金属薄壁管在脉动液压成形时的塑性硬化规律、动态摩擦特性、组织结构演变、起皱规律的分析研究，揭示脉动液压加载方式提高金属薄壁管液压成形性的机理。具体内容包括：研究基于脉动液压成形环境下金属薄壁管材料的塑性硬化规律，提出基于脉动液压环境构建金属薄壁管的塑性硬化模型的方法；研究金属薄壁管脉动液压成形时的动态摩擦特性，提出测定脉动液压成形时金属薄壁管导向区动态摩擦系数的方法，揭示脉动液压对导向区动态摩擦特性的影响规律；研究脉动液压加载对金属薄壁管液压成形时组织结构演变的影响规律，揭示液压成形能力与微观组织演变、脉动液压参数的关系；研究脉动液压加载条件下金属薄壁管成形时皱纹的控制及利用，提出使胀形区的微小褶皱交替处于"产生?胀平"平衡状态的条件及控制方法，揭示这种平衡状态在提高金属薄壁管成形性方面的作用。该项目将为脉动液压成形技术奠定理论基础，为脉动液压成形技术的应用提供科学依据和技术支撑。

通过对金属薄壁管在脉动液压成形时的塑性硬化规律、动态摩擦特性、组织结构演变、起皱规律的分析研究，揭示脉动液压加载方式提高金属薄壁管液压成形性的机理。取得了如下进展：研究了基于脉动液压成形环境下金属薄壁管材料的塑性硬化规律，提出了基于脉动液压环境构建金属薄壁管的塑性硬化模型的方法；研究了金属薄壁管脉动液压成形时的动态摩擦特性，提出了测定脉动液压成形时金属薄壁管导向区动态摩擦系数的方法，揭示了脉动液压对导向区动态摩擦特性的影响规律；研究脉动液压加载对金属薄壁管液压成形时组织结构演变的影响规律，揭示了液压成形能力与微观组织演变、脉动液压参数的关系；研究了脉动液压加载条件下金属薄壁管成形时皱纹的控制及利用，提出了使胀形区的微小褶皱交替处于“产生↔胀平”平衡状态的条件及控制方法，揭示了这种平衡状态在提高金属薄壁管成形性方面的作用。该项目将为脉动液压成形技术奠定理论基础，为脉动液压成形技术的应用提供科学依据和技术支撑。.共发表标注资助的学术论文23篇：其中，英文SCI源期刊论文9篇，英文EI论文20篇，中文核心期刊3篇。获得国家授权发明专利2项，实用新型专利1项。参加境外国际学术会议3次，境内国际学术会议4次。培养博士生1 人，硕士生6人。