CAREER: Impact Resistance and Structural Health Monitoring of Bistable Composite Structures

该项目提倡设计和使用复合双稳态结构，这是一种基于材料的机制，可以延迟和控制能量吸收。双稳结构的发展是为了使损伤分布在更大的体积上，而不是一个局部区域，从而大大提高了耐撞性。复合双稳结构特别有吸引力，因为它可以定制它们，以便在强度和伸长率之间有适当的权衡。这允许结构以故障安全的方式运行，而没有复合材料通常具有的脆性。本文将对具有高抗冲击/重量的二维双稳态复合材料结构进行研究、制造和落重塔试验，通过计算非弹性能量曲线和冲击性能图进行分析，并使用商业软件ABAQUS进行有限元建模。因此，本研究的第一部分将破坏性测试作为设计此类结构的关键方面。在本研究的第二部分，结构健康监测技术将用于识别双稳抗冲击结构的冲击损伤。在单片复合材料和夹层复合材料的常规检查中，由于冲击造成的损伤可能是不可见的，但它会极大地影响结构的强度，并可能带来灾难性的后果。这个问题极大地影响了人们使用复合材料的信心，也影响了复合材料结构的损伤评估技术。复合材料在航空航天、土木工程、船舶建造和汽车工业等大型结构中的应用越来越多，这可能会导致对失效机制的不清楚理解和未被发现的损坏将产生灾难性后果。改善能量吸收、耐撞性和对冲击损伤的探测将促进和加强复合材料在需要高损伤容纳度和能量吸收特性的应用领域的使用，例如在公路车辆、铁路车辆、航空和航天器结构、船舶和潜艇、陆上和离岸设施的设计以及在地震多发和危险多发地区的建筑。将积极招收女学生和代表性不足群体的学生。在全国范围内，将举行大学生设计耐撞结构和地方中学生设计试验台部分的“耐撞复合材料学生竞赛”。这项最新的活动将通过a)工程学院的学生发展和招聘办公室进行，该办公室一直在招募代表性不足的学生，b)加州大学戴维斯分校工程联合委员会，这是一个由工程相关组织的学生代表组成的联盟，该委员会积极开展外展活动。

This project advocates the design and use of composite bistable structures, a material-based mechanism which allows delayed and controlled energy absorption. Bistable structures are developed in order to have damage distributed over a large volume instead of one localized area, with resulting greatly improved crashworthiness. Composite bistable structures are particularly attractive because it is possible to tailor them in order to have the right trade-off of strength and elongation to failure. This allows the structure to behave in a fail-safe manner, without the brittleness that typically characterizes composites. Two-dimensional bistable composite structures with high impact resistance/weight will be investigated, manufactured, tested with a drop-weight tower, analyzed through the calculation of inelastic energy curves and impact performance maps, and modeled with finite elements using the commercial software ABAQUS. The first part of the proposed research uses therefore destructive testing as a key aspect of the design such structures. In the second part of the proposed research, structural health monitoring techniques will be carried out to identify impact damage in the bistable impact-resistant structures. Damage due to impact may be invisible in routine inspections of monolithic and sandwich composites, however it dramatically affects the strength of the structure, with possible catastrophic consequences. This issue has greatly influenced people's confidence in using composites, as well as damage assessment techniques of composite structures.Increasing composite use in large structures in aerospace and civil engineering, ship construction, and automotive industries has the risk that not clearly understood failure mechanisms and undetected damage will have catastrophic consequences. Improvement of energy absorption, crashworthiness and detection of impact damage would promote and enhance the use of composites in applications where high damage tolerance and energy absorption properties are needed, for example in the design of road vehicles, rail vehicles, air and spacecraft structures, ships and submarines, on- and off-shore installations and for constructions in earthquake-prone and hazard-prone areas. Female students and students from underrepresented groups will be actively recruited. A national student competition will be held on crashworthy composites, where college students will design crashworthy structures, and students from local middle schools will compete for the design of a section of the test-rig. This latest activity will be carried out through a) the Student Development and Recruitment Office of the College of Engineering, which has a consistent track-record of recruiting underrepresented students, and b) the UC Davis Engineering Joint Council, a consortium of student representatives from the Engineering-related organizations, which is active in outreach activities.