Floors for Preventing Hip Fractures

[801018 . mcmahon]该提案是一项研究，将使用连续介质力学的广泛比较和分析方法来确定防止髋部骨折的防摔地板垫的最佳设计策略。我们的目标是在现有的地板上铺设一个垫系统，它的行为就像普通行走的传统硬地板，但在受到冲击时，它会在骨骼突出处局部塌陷。将研究三种可选的设计策略。这些策略包括：(1)刚性和弹性泡沫，(2)刚性和弹性蜂窝，以及(3)本研究中引入的新概念“颗粒空气”。GranulAir的概念是在压缩下的颗粒材料的顶层，由一个充气袋支撑，其中包含挡板作为拉伸元件。这三种设计的目标是拥有一个非常非线性的力-挠度曲线，在低应力下具有非常陡的斜率，在可控的施加应力下具有明显的屈服。比较不同设计方案性能的方法包括模拟冲击的有限元分析、颗粒材料在直接剪切中的测试，以及使用准静态测量的伺服液压试验机和动态测量的专用冲击试验机（替代骨盆）对原型进行测试。此外，实用和经济方面以及教育成分是该建议的一部分

9801018McMahonThis proposal is on research which would use broad comparisons and analytical methods from continuum mechanics to identify the best design strategy for a fall-safe floor pad to prevent hip fracture. The goal is a pad system to be laid over existing floors that behaves like a conventional hard floor for ordinary walking, but collapses locally beneath a bony prominence upon impact. Three alternative design strategies will be investigated. These strategies include the investigation of: (1) rigid and elastic foams, (2) rigid and elastic honeycombs, and (3) a new concept introduced in this research called "GranulAir". The GranulAir concept features a top layer of granular material under compression, supported on an inflated bag containing baffles acting as tensile elements. The goal of all three designs is to have an extremely nonlinear force-deflection curve, with a very steep slope for low stresses and a pronounced yield at a controllable applied stress. Methods for comparing performance among the design alternatives include finite-element analysis for simulated impacts, testing of granular materials in direct shear, and testing of prototypes using both a servohydrolic tester for quasistatic measurements and a specialized impact tester (surrogate pelvis) for dynamic measurements. In addition, the practical and economic aspects and an educational component are part of the proposal.***