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

生物组织和生物材料总是受到体内复杂的动态和重复载荷和变形的影响，这些载荷和变形控制着它们的力学性能。为了详细研究这些力学性能，我们需要一种能够在准确测量载荷和变形的同时，顺利地对试件施加各种载荷和变形模式的测试系统。为了满足这些要求，开发了一种新型的材料测试系统。测试系统的特点如下：(1)系统安装了两个伺服液压执行器（Tokyo Koki Seizosho, Ltd.），可以平稳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所需值。(2)宽度分析仪（Hamamatsu Photomics Co.）通过试样表面两个标记物之间距离的变化来确定应变。(3)将称重传感器、位移传感器、宽度分析仪的模拟输出电压转换成数字信号存储在个人计算机中，然后进行处理。(4)在各种溶液中进行测试，温度保持在37ºC。通过对兔髌骨肌腱进行高速拉伸试验和循环加载试验，以及对高强度聚合物纤维及其复合材料进行疲劳试验，对该系统的性能进行评价，用于韧带假体的研制。这些结果表明，该系统对具有多种力学性能的各种生物组织和生物材料的评价非常有用。

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.