| The knee joint is the most complex one in the human body. It transmits load, participates in the movement and assists to maintain momentum. The knee joint is composed of tibia and femur joint and patella and femur joint, which bear much more load than imagined. The knee joint is located between the longest two levers. These characteristics make it apt to be injured. Both domestic and abroad, many studies have focused on the injures and reconstruction of the anterior cruciate ligament(ACL), but there are few reports on the biomechanics and the reports on the viscoelasticity properties, such as relaxation of stress ,creep, are fewer. ACL belongs to biosolid and most of biosolids are viscoelastic material. The viscoelastic properties of ACL fit in with the need of anatomy and function. If scholars want to reconstruct the injured ACL, using the tissue from the same body or another, or study the replacement of ACL, they have to learn tensile stress,strain,stretch ratio,relaxation of stress and creep of ALL. Based on those facts, we performed tensile force,relaxation of stress and creep experiment on ACL, which was havested from human cadavers. We aquired not only the data of tensile stress,strain,stretch ratio,elastic modulus,relaxation of stress and creep but also the curve of the relaxation of stress and the creep of ACL. After processing the data, we gained the functions and curves of the relaxation of stress and the creep. At the same time, we got the regress coefficicent. During the experinent we pulled 8 samples, which were havested from ACL,cut by scalpel. The samples are 22-25mm long, 10-12mm wide, 2.4-2.6 thick, measured by the reading microscope JXD-2. We used automatic electronic mechanical test machine AG-10TA to test the samples. The load was delivered by the photoelectric coding; the strain was delivered by the strain unit of the machine. The machine can increase the speed of stress and strain automatically and keep the stress and the strain fixed. After the experiment was finished, the result was exported by the computer automatically. The data of the tensile experiment were expressed by mean ±standard deviation. The result of the tensile experiment showes that the ultimate load is 379N; the ultimate strength is 9.81Mpa; the elastic modulus is 295Mpa; the biggest strain capacity is 23.13%.the relation between tensile stress and strain is expressed:T(ε)=0.0008+0.1592x-0.0172x~2+0.0046x~3-0.0004x~4 The result of the relaxation of stress showes that the relaxation of stress is bigger during the early 600 seconds, then the stress decreases slowly, until at the time of 7200 second, the curve reaches a balance; the curve of the relaxation of stress varies in logarithimic relation; the relaxation of stress of 7200 second is 1.05Mpa; the relaxation of stress formula of ACL is expressed: K(λ,t)=(0.0601lnt+1.0664)( 0.0008+0.1592x-0.0172x~2+0.0046x~3-0.0004x~4) The result of the creep showes that the change of the creep capacity is bigger during the early 600 seconds, then the creep capacity increases slowly, until the 7200 second, the curve of the strain reaches a balance; the curve varies in experimental relation; the creep capacity of 7200 second is 6.82%; the normalized creep formula of ACL is expressed: The purpose of this experiment provides reference to reconstrution...
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