Development and Evaluation of Multiaxial and Dynamic Material Test System for Biological Tissues and Biomaterials

生物组织和生物材料在体内总是受到复杂的动态重复载荷和变形的作用，这些载荷和变形控制着它们的力学性能。为了对这些力学性能进行详细的研究，我们需要一种测试系统，该测试系统能够在准确测量载荷和变形的同时，将各种载荷和变形模式平稳地施加到测试样本上。为了满足这些要求，开发了一种新的材料测试系统。试验系统的特点如下：（1）两台伺服液压作动器（东京工机精商公司）;安装在系统中，可以顺利地对试样施加各种模式的载荷和变形。施加在试样上的载荷或位移通过闭环电路控制在期望值。(2)宽度分析仪（Hamamatsu Photomics Co.）用于根据样本表面上两个标记之间的距离变化确定应变。(3)来自称重传感器、位移传感器和宽度分析仪的模拟输出电压被转换成数字信号并存储在个人计算机中，然后进行处理。(4)通过对兔髌腱的高速拉伸试验和循环加载试验以及高强度聚合物纤维及其复合材料的疲劳试验，评价了该系统的性能，并对该系统用于韧带假体的研制进行了评价。这些结果表明，该系统是非常有用的各种生物组织和生物材料，具有广泛的力学性能的评价。

Biological tissues and biomaterials are always subject to complicated dynamic and repetitive load and deformation inside the body, which control their mechanical properties. For the detailed studies of those mechanical properties, we need a test system which can smoothly apply various modes of load and deformation to test specimens while accurately measuring load and deformation. To satisfy these requirements, a new material test system was developed. The features of the test system are as follows :(1) Two servo-hydraulic actuators (Tokyo Koki Seizosho, Ltd.) are installed into the system, which can smoothly apply various modes of load and deformation to a test specimen. The load or displacement imposed on a test specimen is controlled at a desired value by means of the closed-loop circuit.(2) A width analyzer (Hamamatsu Photomics Co.) is used to determine strains from changes in the distance between two markers on the specimen surface.(3) Analog output voltage from load cells, displacement transducers, and the width analyzer are converted into digital signals and stored in a personal computer, and then processed.(4) Tests are carried out in various kinds of solutions, being kept the temperature at 37ﾟC.Performances of the system were evaluated by carrying out high speed tensile tests and cyclic loading tests of rabbit patellar tendon as well as fatigue tests of high strength polymeric fibers and their composite materials for the development of ligament prosthesis. These results indicate that this system is very useful for the evaluation of various kinds of biological tissues and biomaterials which have a wide variety of mechanical properties.