Role of damage in the failure of heterogeneous materials

拟议的研究计划将使用皇后大学最先进的微型计算机断层扫描(MicroCT)设备，配备室内加载平台，以获取随着不同种类材料逐渐加载到破坏而形成的内部损伤的3D图像。我们将考虑两类非常不同的非均质材料：钢铁和铝合金薄板材料，它们含有在施加塑性应变时会形成小空洞的硬第二相颗粒，以及松质骨组织(即长骨末端和椎骨中的多孔组织)，由于日常机械循环加载，松质骨组织会积累微裂纹。虽然这两种材料有很大的不同，但将采用共同的调查方法来研究损伤在导致灾难性故障中的作用。*将进行的研究是基础性的，重点是控制全球灾难性材料故障发生的关键局部特征。然而，通过这项研究获得的知识对一些受体是有用的。要研究的钢和铝合金板材牌号用于许多结构应用中，例如汽车工业中的汽车车架和车身覆盖件，在这些应用中，在部件制造过程中或在使用期间过早材料失效是一个持续存在的问题。因此，这一结果对材料制造商和零部件制造商都具有潜在的意义。对于骨的研究来说，松质骨的结构、微裂纹的存在以及由此产生的断裂强度之间的关系是非常复杂的。更好地了解这一关系不仅会促进我们对这种鲜为人知的破坏行为的了解，而且还会导致生物力学技术的改进，如合成骨支架和诊断成像设备。*这项研究的主要成果和影响将是更好地理解损伤在金属合金和松质骨破坏中的作用，并建立改进的或新的模型来预测这种行为。从事这项研究的高素质人员将在以下领域获得宝贵的技能：图像处理、计算机编码、材料表征(光学和扫描电子显微镜)、机械夹具和测试方案的设计、高级数据分析(例如统计学)、有限元方法建模、项目管理、问题解决、批判性思维以及口头陈述和技术写作技能。*松质骨破坏的研究代表着材料科学和工程中的一个非传统话题，可能更吸引女性和该领域中代表性不足群体的人，以及其他相关学科，例如机械工程。**

The proposed research program will use a state-of-the-art micro-computed tomography (microCT) facility at Queen's University, equipped with an in-chamber loading stage, to acquire 3D images of internal damage that develops as heterogeneous materials are progressively loaded to failure. Two very different classes of heterogeneous materials will be considered: steel and aluminum alloy sheet materials containing hard second-phase particles that nucleate small voids when subject to applied plastic strains, and cancellous bone tissue (i.e. the porous tissue in the ends of long bones and in vertebrae) that accumulates microcracks as a result of everyday mechanical cyclic loading. While these two materials are very different, a common investigative approach will be employed to study the role of damage in causing catastrophic failure.******The research to be undertaken is fundamental in nature, focusing on key local features that govern the onset of global catastrophic material failure. However, the knowledge to be gained by this research is of use to a number of receptors. The grades of steel and aluminum alloy sheet materials to be studied are used in a number of structural applications, such as car frames and body panels in the automotive industry, where premature material failure during part manufacturing or while in service is an ongoing issue. Hence the results are of potential interest to both material fabricators and part manufacturers. For the bone research, the relationship between the structure of cancellous bone, the presence of microcracks, and the resulting fracture strength is very complex. A better understanding of this relationship would not only advance our knowledge of this poorly understood failure behaviour, but it would also lead to improvements for biomechanical technologies, such as synthetic bone scaffolds and diagnostic imaging devices.******The major outcomes and impact of this research will be a better understanding of the role of damage in the failure of metal alloys and cancellous bone, with improved or new models to predict this behaviour. Highly-qualified personnel who work on this research will gain valuable skills in areas of image processing, computer coding, materials characterization (optical and scanning electron microscopy), design of mechanical fixtures and testing protocols, advanced data analysis (e.g. statistics), finite element method modelling, project management, problem solving, critical thinking, and oral presentation and technical writing skills.******The study of damage in the failure of cancellous bone represents a non-traditional topic in materials science and engineering that is likely to be more attractive to women and persons from under-represented groups in this field, as well as other related disciplines, e.g. mechanical engineering.**