超声能场与搅拌摩擦焊塑性流变材料的耦合作用机理

项目名称： 超声能场与搅拌摩擦焊塑性流变材料的耦合作用机理

项目编号： No.51475272

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 机械、仪表工业

项目作者： 武传松

作者单位： 山东大学

项目金额： 85万元

中文摘要： 超声可降低材料的变形阻力，是一种能耗低、利用率高的辅助能量。前期研究表明，在搅拌头前方待焊工件上施加超声能场，可减少材料塑性流变所需的摩擦热量；降低焊接载荷并改善焊接质量的工艺效果明显。但超声改变摩擦搅拌区塑性变形材料行为的机制，尚未阐明。本项目拟研究搅拌摩擦焊接过程中超声能场与塑性流变材料的相互作用机理。探究超声波在搅拌头附近塑性变形材料中的传输、耦合及作用规律；构建摩擦搅拌区超声体积效应与表面效应的描述和表征方法；阐明超声能场改变材料屈服应力和流动应力的物理机制。提出超声作用下材料本构关系的修正方法，建立超声能场-应变场-流场-热场的耦合模型，定量分析和测试超声能场作用下搅拌头附近材料塑性流动行为、产热特点、温度分布特征等；实现超声参量、焊接工艺参数与接头组织性能之间的优化与匹配。为有效地指导超声能量在搅拌摩擦焊接过程中的合理应用、提升我国高强铝合金结构的焊接制造水平奠定坚实基础。

中文关键词： 搅拌摩擦焊；超声能场；塑性流变材料；耦合作用；物理机制

英文摘要： Ultrasonic energy can decrease the deformation resistance of materials, and is an assisted energy source of low power consumption and high efficiency. Preliminary studies have shown that exerting ultrasonic energy on the metal to be welded in front of the friction stir tool can lower the required friction heat of materials' plastic deformation, and there is obvious process effectiveness of lowering welding loads and improving weld quality. However, the way how ultrasonic energy changes the behavior of the plastically deformed material is still unrevealed. This project will get deep insight into the underlying interaction mechanism between the ultrasonic energy field and the plastically deformed material in FSW. The transmission, coupling and action regularities of the ultrasonic energy within the plastically deformed material in the vicinity of the tool is explored. The describing and characterizing methods of the volume effects and surface effects due to ultrasonic energy in friction stir zone are developed. The physical reasons why ultrasonic energy field changes the materials' yield stress and flow stress are elucidated. The method to modify the constitutive relation is put forward. The coupled model is established to describe the correlations of the ultrasonic field, strain field, fluid flow field and temperature field. The plastic flow behaviors, heat generation characteristics, and temperature distribution features of the material around the tool under the action of ultrasonic energy field are quantitatively analyzed and experimentally measured. The optimization and match between the ultrasonic variables, the welding process parameters and the weld joints' microstructures & properties are realized. It will lay solid foundation for effective guiding the appropriate utilization of ultrasonic energy in FSW process and raising the technological level of welding high strength aluminum alloy structures in China.

英文关键词： Friction stir welding;Ultrasonic energy field;Plastic material flow;Coupled interaction;Physical mechanisim