塑料齿轮轮齿疲劳折断机理初析

对塑料齿轮疲劳破坏过程作了讨论和分析，提出了疲劳裂纹的萌生与扩展的银纹模式，认为轮齿表面节点附近热拉伸内应力是导致银纹形成的重要原因。

Experimental study on mechanical properties of dowel bar embedded in concrete under fatigue loads

To investigate the mechanical properties of a dowel action under fatigue loads, nine reinforced concrete specimens were fabricated, and the monotonic and fatigue loadings were performed on these specimens, respectively. All of these specimens were divided into two series. Six specimens in SeriesⅠwith different bar diameters of 12, 20 and 25 mm were subjected to monotonic loads and were used to confirm the ultimate bearing capacity. The remaining three specimens in Series Ⅱ were subjected to fatigue loads and were designed to investigate the attenuation character of dowel action and the fatigue failure modes. The test results show that the accumulated fatigue damage due to fatigue loads can reduce the ultimate bearing capacity of specimens. With the increase in fatigue loads, the failure mode can transform to fatigue rupture of the dowel bar under the serviceability loading state,i. e. 55% of the monotonic capacity. The fatigue life is determined by the fatigue properties of steel and concrete.Based on the test data, the failure process of dowel action can be divided into two stages： the accumulation of fatigue damage and the fatigue rupture of dowel bar.

Inspection Plans for Structure Fatigue Deterioration of Bulk Carrier on Active Service

Evolutionary algorithm is applied as an optimization method in this paper. The increment of cumulative failure probability of fatigue, inspection cost, inspection interval and means are adopted as limiting condition, objective function and optimization variable respectively. According to fatigue characteristics of ship structure, the optimization research of inspecting fatigue deteriorating is carried out. The optimal inspection planning of minimal inspection cost is chosen. An example of computation and comparison of inspection plans is given. The results demonstrate that an optimal inspection plan considering security and economics can be chosen by the means in this paper.

Fatigue reliability analysis of kiln welded shell

This paper presents a probabilistic reliability method for the welded shell during crack growth. The crack growth model incorporated with a failure assessment diagram（FAD） , which can provides a better estimation of the critical crack length, is developed to describe fatigue failure. All variables for particular welded joints of the shell are studied. Among them, the stress variables are based on the calculated stress by using the finite element （FE） code ANSYS. Fatigue reliability analysis of the welded shell is performed by using the Monte Carlo simulation method. The failure probability curve of the example kiln is significantly useful to determine the repair schedule of shell cracks.

Hardness-Based Non-destructive Method for Developing Location Specific S-N Curves for Fatigue Life Evaluation

This paper first describes the importance of using location specific S-N curves for fatigue damage assessment of existing steel structures. It discusses the existing concepts and methods for developing S-N curves using empirical formulae and monotonic strength parameters, such as the ultimate tensile strength and hardness. It also discusses relationships among these monotonic parameters. Then it presents formulae for developing hardness-based full range S-N curves for medium strength steels. The formulae are verified using experimental data obtained from both monotonic and cyclic testing. Finally, it describes the advantages of these hardness-based formulae for developing location specific S-N curves as hardness testing is a non-destructive test which can be carried out on specific locations in structures.

Investigating the Effect of Fatigue on Fracturing Resistance of Rocks

There is no doubt that an understanding of brittle rock fracturing is a key element in the solution of many engineering problems that involve rock structures. Some rock structures such as bridge and dam abutments and foundations, and tunnel walls, undergo both static and cyclic loading caused by drilling and blasting, and vehicle-induced vibrations. This type of loading often causes rock to fail at a lower than its static strength due to the effect of rock fatigue. A series of laboratory diametrical compression tests was performed on Brisbane tuff disc specimens to investigate their mode-I fracture toughness response to static and cyclic loading, as a function of the applied load. Both the static and cyclic loading tests were carried out on CCNBD （cracked chevron notched Brazilian disc） rock specimens. In the tests described herein, the reduction in fracture toughness under dynamic cyclic loading was found to be up to 48% of the static fracture toughness. Contrary to the static tests, the cyclic tests produced much more crushed material in front of the tip of the chevron notched crack.

Effect of Seismicity in the Taiwan Straits on the Southeast Coastal Area of the Chinese Mainland

Based on the available and supplementary survey data,it analyzes the effect of seismicity in Taiwan and the Taiwan Straits on the southeastern coastal area of the Chinese mainland and discusses its roles in seismic hazard prevention and textual research of historical earthquakes. The results show that the frequency of strong earthquake in Taiwan Region is high,with a time interval ranging from several to dozens of years,but the maximum influence intensity of seismicity from there to the coastal areas of the Chinese mainland is only VI degree; while the maximum influence intensity of the seismicity along the littoral fault zone located on the west of the straits reaches VIII ～ IX degree because of the shorter distance to the Chinese mainland,though the frequency of strong earthquakes is lower than that of the Taiwan Region. Strategies for protecting against seismic hazards in the southeastern coastal area of China are proposed. Besides focusing on the effect of strong earthquakes of the littoral fault zone,attention also has to be paid to the low-cycle fatigue failure of engineering structures induced by the earthquakes in Taiwan and the stir effect on society induced by earthquake phobia. It is concluded that it would be more accurate and proper to take the May 19,1517 earthquake recorded in the Chinese mainland area as the influence of a strong earthquake in the Taiwan Region.