Design Of A Bending Material Test Machine And Measurement Of Viscoelastic Properties Of Fish Material

The research of the mechanical property of the biomaterial is one of the most significant parts in the biomechanics, which plays an important role in understanding the mechanism of fish swimming and has important engineering value. In this thesis a special type of material test machine used in bending test was designed, which can be used to measure the viscoelastic properties of the fish material. Through simulating fish oscillation, the viscoelastic properties of the caudal fin and intervertebral joint in a crucian carp were measured, a complex number model was adopted to analyze the results of the biomaterial test and the effect of the viscoelastic on fish swimming was discussed.The main results of this thesis are as follows:1. Design process, the details of the structure and systems and the calibration of of the material test machine are presented.2. The specimens of an elastic material (coppor) and a viscoelastic material (rubber) are tested. The material characteristic is calculated. Comparison between the obtained results and the known properties of elastic and viscoelastic materials shows that the results are reasonable and the design of the test machine is suitable.3. Test results of the caudal fin ray in crucian show that the moment(M) needed by swinging the caudal fin increases as the swing amplitude, while the phase angleδof hysteresis and the loss modulus E2 decrease as the amplitude and the frequency increase. The storage modulus E1 increases slightly as the frequency for the amplitude of 3°, while it decreases for the amplitude of 5°.4. Testing results of the intervertebral joint in crucian show that the intervertebral joint in the anterior part of fish body needs larger moment than the posterior part. The phase angleδof hysteresis and loss modulus E2 decrease as the frequency increases.δand E2 of the intervertebral joints in the posterior part are less than in the anterior part. The storage modulus E1 decreases slightly as the frequency increases and E1 of the posterior part is larger than the anterior part. The phase angle of hysteresis is very small and close to zero as the amplitude increases.