In Chapter 2, for T300/QY8911 Carbon/Bismalimide composite laminates, three kinds of basic tests (fatigue of [0]i6 tension-tension, [90] ie tension-tension and [0/90]4S shear-shear) were firstly performed to obtain S-N curves for unidirectional laminates, which were then used as input for the computer codes.

The tension-tension fatigue tests have been performed under vacuum at room-temperature, 1100℃, 1300℃, 1500℃ , for stress from 200MPa to 300MPa, ratio of 0. 1 and 0. 5, sinusoidal loading frequency of 20HZ and 60HZ .

The changes of surface topography, surface roughness, surface residual stress and compressive residual stress field caused by shot peening and their effects on tension-tension fatigue properties in Ti-10V-2Fe-3Al titanium alloy were studied.

The high temperature low cycle fatigue properties have been studied for three Crl5-Ni2S alloys with carbon contents of 0.009, 0.099 and 0.16 (wt. %). Uniaxial tension-tension fatigue test with a holding time for one minute has been conducted.

For T300 /QY8911 Carbon/Bismalimide composites, three kinds of t ypical tests (fatigue of 16 tension-tension, 16 tension-tension an d 4s shear-shear) are performed to obtain the S-N curves for unidirect ional laminates, which are used as input for the above procedure.

In order to remedy this ambiguous definition of failure in this zone for the compression strong materials or in the domain of the tension-tension octant for the tension strog materials an improved version of the EPFS was introduced in this paper.

Fatigue crack growth rate studies in tension-tension on IN-744 sheet gave results very comparable to those reported for other steels.

The fatigue crack propagation rate (FCPR) in 316L austenitic stainless steel (ASS) and its weldments was investigated, at two loading amplitudes, 7 and 8.5 kN, under tension-tension mode.

During tension-tension fatigue studies, a higher specimen temperature was observed at 700 than at 10 Hz.

The cyclic compression-compression fatigue life of the metallic glass is about a factor of 10 higher than the cyclic tension-tension fatigue life at the same stress ratio.

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 life...

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.