Based on the prediction model, the probability distribution of fatigue life and critical value of accumulated fatigue damage of notched mild carbon steel under multilevel tension tension variable amplitude loading is predicted according to Miners rule and expressions of fatigue life with given survivabilities obtained from rotary bending fatigue test under constant amplitude, and checked by test results.

It is shown that both the predicted fatigue life and the test results of fatigue life of notched elementals of 45 carbon steel under tension tension variable amplitude loading follow the log normal distribution, and the two distributions agree well with each other.

The responses of fatigue limit to mean stress of 2Cr13 steel were studied through tension tension and tension compression fatigue tests between room temperature and 450 ℃.

The random distribution of life is tested by EDF statistics values. Test data of T300/QY8911 16 , 24 and 3S under tension tension fatigue had been used for Monte Carlo simulation. The result shows that the life obeys Weibull distribution.

In the end, the physical quality of antimicrobial films was studied including of intensity of tension, tension rate and coefficient of oxygen permeation.

The test results showed that the influence of drawing ratio,speed and temperature on the tension,tension fluctuation and irregularity of the fiber were obvious.

Comparafive Investigations of the fracture surfaces of woven Gr/Ep Composite coupons have been made in this stady by using ISI-60 SCANNING ELECTRON MICROSCOPE. Specimens of static and tension-tension fatigue tests at low and high temperatures were chosen for comparison. A primary observation was that during the fatigue tests the visible delimi tations at the edges often occured after 2×104 to 3×104 cycles. The delimitations in room temperature fatigue coupon were more serious than in the static coupon....

Comparafive Investigations of the fracture surfaces of woven Gr/Ep Composite coupons have been made in this stady by using ISI-60 SCANNING ELECTRON MICROSCOPE. Specimens of static and tension-tension fatigue tests at low and high temperatures were chosen for comparison. A primary observation was that during the fatigue tests the visible delimi tations at the edges often occured after 2×104 to 3×104 cycles. The delimitations in room temperature fatigue coupon were more serious than in the static coupon. The most serious delimitations were found in the high temperature fatigue coupon. The cracks in the matrix have the same tendency as well. The breakage surface of single fiber of fatigue coupon was more smooth than the static's.I would like to express my thanks to Prof. S. Hanagud, R. Carlson, J. Craig, Dr. R. Sigman and R.G. Clinton for all the helps they gave me in the work.

In this paper tension-tension (R=0.1) fatigue behaviout and residual static tensile strength of unidirectional graphite/epoxy composite were studied by using GB 3354-82 specimens of straight-sided type with long gage length (GB-National Standard, China). The S-N curve and fatigue limit were obtained by means of test method in group and the staircase method. The number of stress cycles, at which the machine stops or the load drops due to the damage or crack occuring in the specimen, is taken as the...

In this paper tension-tension (R=0.1) fatigue behaviout and residual static tensile strength of unidirectional graphite/epoxy composite were studied by using GB 3354-82 specimens of straight-sided type with long gage length (GB-National Standard, China). The S-N curve and fatigue limit were obtained by means of test method in group and the staircase method. The number of stress cycles, at which the machine stops or the load drops due to the damage or crack occuring in the specimen, is taken as the life of the specimen at that stress level. The S-N curve is a straight line and tends to horizon near the fatigue limit.The fatigue limit is 0.325σb.The failure of specimens resulted from the development of the longitudinal cracks. The appearnce of longitudinal cracks is apparently due to shaer fractures. The shear fractures show that the fatigue behavior obtained bears a close relation with the properties of matrix and interface. The load-carrying capacity of fibers has not been fully utilized, so the S-N curve and fatigue limit obtained correspond to the lower limit of the tension-tension fatigue behaviour of graphite/epoxy unidirectional composite. The specimens with longitudinol cracks were also tested for residual static tensile strength which was found to be 0.7 σb or more. And the curves of load-deformation are straight lines up to 0.5σb then the loads keep increasing and fluctuating until the failure of specimens.

In order to study the fatigue life distribution of unidirectional graphite/epoxy composite, 50 specimens were tested at same stress level (σmax=48kgf//mm2)· X2 test and check with the graph on the normal probability paper are used. If the logarithmic fatigue life of these 50 specimens as a sample is taken from same population of Gaussian distribution, the theoretical frcquncy function cf this normal population can be obtainedThese data are dawn OH normal probability paper and we find these data are locatednear...

In order to study the fatigue life distribution of unidirectional graphite/epoxy composite, 50 specimens were tested at same stress level (σmax=48kgf//mm2)· X2 test and check with the graph on the normal probability paper are used. If the logarithmic fatigue life of these 50 specimens as a sample is taken from same population of Gaussian distribution, the theoretical frcquncy function cf this normal population can be obtainedThese data are dawn OH normal probability paper and we find these data are locatednear the linelogN= 6.0049+ 0.9330 Upwith linear dependence coefficient r=0.9950. The test data of 50 specimens at same stress levl show that the tension-tension fatigue life distribution of unidirectional graphite/ epoxy composite follows the logarithmic Gaussian distribution.