NONLINEAR STRESS/STRAIN BEHAVIOR OF CORTICAL BONE

皮质骨的非线性应力/应变行为

• 批准号: 2748657
• 负责人: DWIGHT T. DAVY
• 金额: $ 24.14万
• 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 2000-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2748657
• 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.

说明(改编自申请人的摘要)： 拟议的研究是为了研究混凝土的非线性力学行为。 从皮质骨的角度看损伤累积的过程。 有相当多的证据表明，大脑皮质的非线性行为 骨骼很大程度上是由于损伤积累造成的。然而，在实践中，骨骼 通常被建模为传统工程材料，最多为 一种各向异性的弹性材料，其强度由多个- 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就可以 在骨应力分析中导致错误的结果和结论 结构。应用程序的广泛假设是损害 累积量度可以预测非线性应力-应变历史 在一般载荷下的骨骼，直到失效。在这项研究中， 申请者将通过实验测量大脑皮质的非线性行为 三种简单加载模式下的骨骼：轴向拉伸、轴向压缩、 还有扭转力。他们建议调查失败的可预测性。 使用可观察到的损害累积的机械措施，例如 最大非线性应变和割线模数退化。他们会寻求 为了应用连续介质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所致损害的领域 通过使用局部应变图谱和原子力显微镜。 拟议的骨力学基础工程研究的目的是 在以下几个方面对知识状况做出了重大贡献 方式。首先，机械测试结果应该有助于确定骨骼 在可接受的伤害累积率方面的强度，而不是 从静态强度测试得出的较不保守的值。第二, 力学测量、建模工作和成像研究相结合 为更完整的描述提供了第一步 材料的非线性行为和多轴破坏过程 骨头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确定 完成任务所需的工作量和方法。 第三，从损伤的角度来描述骨骼的行为 与力学和生物学的耦合有关。预测的能力 损害累积为预测安全水平提供了可能性 修复过程中可以维持骨骼的重复负荷 诚信，这将是描述力量的适当方式 日常生活中的骨质结构。