RESEARCH ON EVALUATION FOR AN ORIGINAL ENGINEERING WORKING MEASURE AGAINST TO THE "MUTISITE-CRACKING" OF SEAMS BETWEEN A PANEL AND ANOTHER PANEL FASTENED BY RIVETSLINE

日本航空“巨无霸飞机”的事故和夏威夷发生的事故让我们记忆犹新。这些事故是由用铆钉线固定的面板和另一个面板之间的接缝“多点开裂”引起的。这些事故给我们带来了非常严重的冲击，因为关于增压飞机机体破裂的“故障安全神话”被彻底打破了。因此，针对“多点开裂”提出新的工程工作措施是一件非常重要的事情。本研究的目的是为了验证首席研究员提出的针对这种“多点开裂”的新工程工作措施的有效性。该方案的要点是，通过采用混凝土处理领域中非常流行的预应力技术，使飞机机体的火焰和桁梁更加努力地工作，确保对受压飞机机体开裂的“失效安全”。为了验证这一建议的有效性，自制了一台计算机控制的拉动式疲劳试验机。在试件产生裂纹后，利用由超声传声器、超声声纳仪和彩色打印机组成的声分析系统对每次实验进行超声声发射测量。由于试验机尺寸过小，加之试件所用材料（普通铝）的刚度不够，没有达到预期的结果。另一方面，同样为了证实该建议的有效性，进行了光弹性实验。通过这种方式，我们得到了预期的结果。

The acsident of JAL's "jumbo-plane" and the acsident occurred in HAWAII are fresh in our memory. These acsidents are caused by the "multisite-cracking" of seeam between a panel and another panel fastened with rivetsline. These acsidents had given us very serious shock for the meaning that the "failsafety-mythology" against to the cracking of pressurized airplane's body was broken thoroughly. So, getting of new engineering working measure against to the "multisite-cracking" is very important matter.The pupose of this research is to corroborate the validity of new engineering working measure against to this "multisite-cracking which have been proposed by head investigator. The gist of this proposal is, by using the prestressing technique which is very popular one in the concrete handling field, to make flames and stringers of the airplane's body work onestep harder and ensure the "failsafety" against to the cracking of pressurized airplane's body.To corroborate the validity of this proposal, a computer controled pulling type weariness testing machine was hand made. After the cracks had broken out on the test pieces, ultrasonic sound emission was measured by the sound analyzing system composed of ultrasonic microphon, ultrasonic sonagrph and color printer, on each experiment.Cause by the dimension of testing macine was too small, and by the stiffnes of material (normal aluminum) used for the test pieces was insufficient, expected result was not obtained.On the other hand, samely to corroborate the validity of the proposal, photoelasitic experiments has been executed.On this way, we get prospectfull result.