A reliability analysis methodology based on the probability fracture mechanics is developed for the wing with main and subordinate components under conisdering several factors, such as crack detection probability, inspection interval, initial flaw distribution, crack growth,residual strength,etc. . The initial fatigue quality(IFQ)of a structural components is represented by an equivalent initial flaw size (EIFS).

improved method for determining the parameters of equivalent initial flaw size(EIFS)distribution is set up in this paper. The time to crack initiation(TTCI)values corre- sponding to gived reference crack size for every specimens in several stress level are obtained. These TTCI values are translatcd into EIFS values bv EIFS master equation.

An evaluation approach is presented to the initial fatigue quality of fastener holes, which is characterized by Equivalent Initial Flaw Size Rating (EIFSR) obtained by back extrapolated fractographic data of constant amplitude loading.

After a period of time, the fatique crack will appear in the tail structure of Boeing serials aircrafts. It is necessary to use Vortex Detection to inspect this kind of flaw.

The identification of the geometrical character of a flaw is then given by the two dimensional inverse Born approximation in a low-frequency range.

We analyzed spatial distribution of the main types of water bodies as well as the cascade structure formed by some biogeochemical barriers near the Ob-Yenisey flaw polynya.

A highly efficient technique of ultrasonic testing using "chord" transducers with elastic protective covers in combination with general-or special-purpose flaw indicators is suggested.

Solution of reciprocal problem of magnetic flaw detection through calculation of multipole moments of an elliptic flaw

An algorithm has been developed for calculating parameters of an effective elliptic flaw (EEF) on the base of changes in the magnetic field intensity in the air.

The variables recorded in the tests were the applied load, number of loading cycles, length of a fatigue crack, strain in sample material, and parameters of AE signals.

The dynamics of the frequency spectrum of the samples is investigated during the development of a fatigue crack.

Features of variation of the frequency spectrum of free vibrations in samples with fused coatings which are characterized by complex kinetics of the development of a fatigue crack are noted.

As SEs are broken, information is obtained simultaneously from acoustic-emission (AE) and tensometric equipment and measurements of the fatigue crack's opening are carried out.

These signals are processed using cluster analysis, which makes it possible to separate the signals emitted by a propagating fatigue crack in the stringer region from the signals arriving from the region of the fracturing gripping jaw.

In this study the sonic resonance technique was used to determine the Young's elastic moduli, the controlled surface microflow technique was used to measure the fracture toughness and the critical strain energy release rate was calculated.The Young's elastic moduli and fracture toughnesses of three different glassy carbons were measured from room temperature to 1023°K. The fracture, oxidized and machined surfaces were investigated and observed by scanning electon microscope. The critical strain energy release...

In this study the sonic resonance technique was used to determine the Young's elastic moduli, the controlled surface microflow technique was used to measure the fracture toughness and the critical strain energy release rate was calculated.The Young's elastic moduli and fracture toughnesses of three different glassy carbons were measured from room temperature to 1023°K. The fracture, oxidized and machined surfaces were investigated and observed by scanning electon microscope. The critical strain energy release rates of the galssy carbons were analyzed and compared with the polycrystalline griphites and carbon-carbon composites.

An elastic analysis of transient temperature field and stress field obtained from finite element method and its program are presented. In this calculation methcd the Weighted Residual Method is used to solve the axially symmerfc transient conduction differential equation directly, then the obtained differential expression is transformed to the formulation of finite element method.The 1st stage turbine disk of an existing engine is used as an example in this paper, its temperature field and stress field during...

An elastic analysis of transient temperature field and stress field obtained from finite element method and its program are presented. In this calculation methcd the Weighted Residual Method is used to solve the axially symmerfc transient conduction differential equation directly, then the obtained differential expression is transformed to the formulation of finite element method.The 1st stage turbine disk of an existing engine is used as an example in this paper, its temperature field and stress field during the various condit'ons of starting, accelerating, maximum, lower power for cooling and shutdown have been predicfed, from which we obtain the result that the position of maximum stress is different from the position of maximum stress amplitude. It is well known that the fatigue cracks always initiate at the position of maximum stress amplitude in the slot bottom.

A local strain fatigue analysis method is presented for evaluation of fatigue life. First, the three parameter elements of load increment, strain increment and stress increment are constructed by using the cyclic stress-strain curve of the material and the cyclic load notched strain curve of notched specimens. Then, the local stress-strain analysis of notched specimens under complex load is made by means of these elements and "availability coefficient matrix"given by R. M. Wetzel. The damage of each cycle is...

A local strain fatigue analysis method is presented for evaluation of fatigue life. First, the three parameter elements of load increment, strain increment and stress increment are constructed by using the cyclic stress-strain curve of the material and the cyclic load notched strain curve of notched specimens. Then, the local stress-strain analysis of notched specimens under complex load is made by means of these elements and "availability coefficient matrix"given by R. M. Wetzel. The damage of each cycle is determined on the basis of local strain amplitude and correction for the effect of mean stress. Last, the damage can be cumulated according to Miner's linear cumulative damage theory and the life can be evaluated.The features of this method consist in adoption of three parameter elements of load increment, stress increment and strain increment; one-step transformation from loadtime histories to local stress and strain-time histories, then the computation procedure is simplified.The example of the Cumulative Fatigue Damage Division of the SAE Fatigue Design and Evaluation Committee has been computed with our program. The crack formation lives of the notched specimens for two materials under vehicle transmission load have been evaluated and the results are quite consistent with W. R. Brose's results and experiments. This demonstrates that the presented method and program are simple, reliable and rapid. This program can work more than 50 peaks per second and may be available for engineering evaluation of the crack formation life.