Papers by Keyword: Fatigue Load

Abstract: To investigate the influence of stress concentration, crack propagation and types of fatigue loading on metal magnetic memory signals, two groups of fatigue experiments with different types of fatigue loading were carried out on Q235B steel welded joint. The normal components of magnetic flux leakage were measured by metal magnetic memory tester in the course of fatigue test, and the fracture surfaces of specimens were observed by scanning electron microscopy after fatigue tests. The experimental results showed that the normal components of magnetic flux leakage filed, as well as the metal magnetic memory signal, changed polarity and their gradients have peak values at stress concentration zones. The zero position of the normal component of magnetic flux leakage changed gradually with increasing cycle numbers. In addition, the metal magnetic memory signal feature of fatigue crack propagation was affected by the loading type clearly. Moreover, a combination of brittle rupture and ductile rupture was obtained in the fracture morphology figure.

Abstract: High-strength bolted connection is widely used for steel structure construction. Because high-strength bolted connection has simple constructability and structural qualification. Especially friction type with high-strength bolted connection has high stiffness and fatigue strength. At this time, initial clamping force is one of main factor to affect the strength and deformation behavior of connection. Therefore, the objective of this study is to investigate reduction of initial clamping force in high-strength bolted connection under fatigue load. And the parameter of this study is the size of the bolt and 3 types of initial clamping force. The analysis is used the finite element analysis program ANSYS Workbench.

Abstract: Fiber reinforced polymer (FRP) has been applied not only for the simple structures but also for the advanced structures such as bridges or highway bridges for sustainable construction. In case of bridges or highway bridges, the structures experience not only static loadings but also fatigue loadings that may limited the serviceability of the bridge structures. In order to extend of the application of FRP on the such bridge structures to have a sustainable structures, the flexural capacity due to fatigue loading should be clarified. Glass composed FRP sheet namely Glass Fiber Reinforced Plastics (GFRP) is most commonly used due to its relatively lower cost compared to the other FRP materials. GFRP sheet is applied externally by bonding it on the concrete surface. Many studies have been done to investigate the flexural capacity of concrete beams strengthened using GFRP sheets. However, studies on the flexural capacity after fatigue loadings are still very rarely. This study presented the results of experimental investigation on the flexural capacity of the strengthened concrete beams after fatigue loadings. A series of concrete beams strengthened with GFRP sheet on extreme tension surface were prepared. Results indicated that after 800000 time of load cycle, the flexural capacity of beams specimens may decrease to only approximately 60%. The beam failed due to delaminating of GFRP sheet.

Abstract: A research study on the fatigue performance of hybrid adhesive joints was carried out to investigate the fatigue performance of adhesive joint and hybrid adhesive joint using dissimilar material. A 3 mm thin plate of aluminium A7075 and stainless steel 304 are used as the adherend material for experimental test and the adhesive used was high performance Araldite epoxy adhesive. Maximum fatigue life was achieved for the hybrid adhesive joint with an optimum overlap length of 59 mm and the adhesive thickness of 0.2 mm. The fatigue damaged occurs on the adherend surface for adhesive joint and adherend crack for hybrid adhesive joint. Results showed an increment of fatigue life with shear stress reduction.

Abstract: In order to conduct a further investigation of the causes of damages in large longitudinal slope of asphalt road pavement under actual heavy load, a three-dimensional finite element model was established by ANSYS finite element software. Through applying impulsive load in this model, the variation of the strains of large longitudinal slope of asphalt road pavement under different conditions was obtained and the influence of gradient on the dynamic response of large longitudinal slope of asphalt road pavement was analyzed. The results show that the strains of large longitudinal slope of asphalt road pavement increased with the increase of load times. Flexure tensile strain and shear strain were similitude with the change tendency of the increase of overloading rate but the data increased significantly. The transversal shear strain increased with the increase of gradient.

Abstract: This paper analyzes three main factors (turbulence intensity, air density, annual average wind speed ) that influence the low wind speed wind turbine fatigue loads, In order to analyze the influence of each main parameters how to affect the fatigue load of low wind speed wind turbine, using a 2000kW wind turbine as an example on the simulation test , 3 turbulence, 4 air density and 7 annual average wind speed were employed. The results show that, with the air density, turbulence intensity and the annual average wind speed increases, the wind turbine of fatigue load increase in rule approximately. Based on the above rule, it can reduce fatigue loads and prolong the life of wind turbine in design optimization of low wind speed wind turbine and sit choice.

Abstract: In today's competitive business environment, it has become increasingly important to reduce manufacturing and raw materials cost. For this purpose, an innovative process of design and manufacturing railway axles is developed. It is based on forging hollow axles which allows a significant reduction in steel consumption. In this work, we tried to analyze how these modifications induced by this new process and design impact the service behavior and particularly the durability face to cyclic loadings that can lead to fatigue failure. In the present study, a numerical chain has been developed going from the simulation of the manufacturing process up to the analysis in fatigue. In the first step, the forging process is modeled in order to predict the residual stress field and the initial plastic strain. From this initial condition, the assembly operation of the wheel on the axle is simulated before the redistribution of stresses and strains under cyclic load. The final objective is to obtain the cyclic loadingpaths, in order to provide the data needed for the analysis of fatigue.

Abstract: Peeling along the interface between FRP and concrete under fatigue load is the common failure pattern for the RC structures strengthened with FRP. In this paper, five groups specimens were subjected to fatigue load to study the fatigue mechanism for bonding interface between carbon fiber laminate (CFL) and concrete. The Δσ~N curves for the bonding interface were derived from the experiments, the laws of strains and slip on interface were analyzed in this paper.

Abstract: For investigating the stiffness changes on reinforced concrete beam at different level of corrosion after fatigue, a group of RC beams were designed with different corrosion ratio, and fatigue test was carried on these specimens. The deflection, strain and crack of these specimens were analyzed in fatigue loading. The results indicate that the effect of corrosion ratio on fatigue performance of RC beams is very obviously.

Abstract: This article combines with finite element method and the rain flow count method, which is using the nominal stress method developed a wind turbine used for structural fatigue analysis method, with 2.0 MW wind and machine hub to analyze the fatigue, calculated the operation lifespan fatigue load of wind turbine in the 20 years. By choosing the hot point of hub, analyzes the wheels fatigue damage characteristics. The calculation results show that: the selection of hot point wheels meet with the requirements of GL standard Fatigue design. This paper can be used in large wind turbine development design and in the process of production design authentication.