NONLINEAR STRESS/STRAIN BEHAVIOR OF CORTICAL BONE

皮质骨的非线性应力/应变行为

• 批准号: 6043221
• 负责人: DWIGHT T. DAVY
• 金额: $ 25.09万
• 依托单位: CASE WESTERN RESERVE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1996
• 资助国家: 美国
• 起止时间: 1996-08-01 至 2001-02-04
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6043221
• 关键词: atomic force microscopy; biomechanics; bone; mechanical pressure; mechanical stress; statistics /biometry; tensile strength

DESCRIPTION (Adapted from the Applicant's Abstract): The purpose of the proposed study is to investigate the nonlinear mechanical behavior of cortical bone from the perspective of a damage accumulation process. There is considerable evidence that the nonlinear behavior of cortical bone is largely due to damage accumulation. However, in practice, bone is typically modeled as a traditional engineering material, at most as an anisotropic, elastic material, with strength described by a multi- axial strength criterion. If failure can result from damage accumulation, the use of simple properties and fixed strength values can lead to incorrect results and conclusions in stress analyses of bony structures. The application's broad hypothesis is that damage accumulation measures can predict the nonlinear stress-strain history of bone under general loading, up to failure. In this study, the applicants will experimentally measure nonlinear behavior of cortical bone in three simple loading modes: axial tension, axial compression, and torsion. They propose to investigate the predictability of failure using observable mechanical measures of damage accumulation such as maximum nonlinear strain and secant modulus degradation. They will seek to apply continuum damage models to describe the experimental behavior, and examine the ability of internal state variables to predict failure. They will further seek to characterize the domain of the induced damage by the use of local strain mapping and atomic force microscopy. The proposed basic engineering study of bone mechanics is intended to make significant contributions to the state of knowledge in several ways. First, the mechanical testing results should help define bone strength in terms of acceptable damage accumulation rates, rather than less conservative values derived from static strength tests. Second, the combined mechanical measurements, modeling effort and imaging studies provide a first step toward a more complete characterization of nonlinear behavior and multi-axial failure processes in the context of bone as a damaging material. The full accomplishment of this goal will require a great deal of work, and the proposed study will help define the amount of work and the methods required to accomplish the task. Third, characterizing the behavior of bone in terms of damage has relevance to coupling of mechanics and biology. The ability to predict damage accumulation provides the potential for predicting safe levels of repetitive loading in which repair processes can maintain bone integrity, which would be the appropriate way to describe strength of bony structures in daily living.

描述（改编自申请人的摘要）：目的 拟议的研究是调查非线性机械行为 从损伤累积过程的角度来看皮质骨。 有大量证据表明皮质的非线性行为 骨骼很大程度上是由于损伤积累造成的。 但实际上，骨 通常被建模为传统的工程材料，最多为 一种各向异性的弹性材料，其强度由多因素描述 轴向强度准则。 如果损坏可能导致故障 积累，使用简单的属性和固定的强度值可以 导致骨应力分析结果和结论不正确 结构。 该应用程序的广泛假设是损坏 累积措施可以预测非线性应力应变历史 骨在一般负荷下的变形，直至失效。 在这项研究中， 申请人将通过实验测量皮质的非线性行为 骨的三种简单加载模式：轴向拉伸、轴向压缩、 和扭转。 他们建议研究故障的可预测性 使用可观察的损伤累积机械措施，例如 最大非线性应变和正割模量退化。 他们将寻求 应用连续损伤模型来描述实验行为， 并检查内部状态变量预测故障的能力。 他们将进一步寻求表征诱发损伤的范围 通过使用局部应变图和原子力显微镜。 拟议的骨力学基础工程研究旨在 在多个方面对知识状况做出了重大贡献 方式。 首先，机械测试结果应有助于定义骨骼 强度是指可接受的损伤累积率，而不是 静态强度测试得出的不太保守的值。 第二， 综合机械测量、建模工作和成像研究 为更完整地表征提供了第一步 非线性行为和多轴失效过程 骨作为一种破坏性材料。 这一目标的全面实现将 需要大量的工作，拟议的研究将有助于定义 完成任务所需的工作量和方法。 第三，用损伤来表征骨骼的行为 与力学和生物学耦合的相关性。 预测能力 损害累积提供了预测安全水平的潜力 重复加载，其中修复过程可以维持骨骼 完整性，这是描述强度的适当方式 日常生活中的骨骼结构。