A fatigue damage model is developed for evaluating accumulative fatigue damage of dumpers. The loading spectrums acted on dumpers are created according to measured strain data in field. The finite element analysis is ...A fatigue damage model is developed for evaluating accumulative fatigue damage of dumpers. The loading spectrums acted on dumpers are created according to measured strain data in field. The finite element analysis is carried out for assessing stress distribution and strength characteristics of dumpers. Fatigue damage indexes and service life are calculated by a modified Palmgren-Miner rule. The investigation shows that fatigue notch factor has a significant influence on the calculation of fatigue damage of dumpers.展开更多
Reliability analysis methods based on the linear damage accumulation law (LDAL) and load-life interference model are studied in this paper. According to the equal probability rule, the equivalent loads are derived, an...Reliability analysis methods based on the linear damage accumulation law (LDAL) and load-life interference model are studied in this paper. According to the equal probability rule, the equivalent loads are derived, and the reliability analysis method based on load-life interference model and recurrence formula is constructed. In conjunction with finite element analysis (FEA) program, the reliability of an aero engine turbine disk under low cycle fatigue (LCF) condition has been analyzed. The results show the turbine disk is safety and the above reliability analysis methods are feasible.展开更多
High strength threaded fasteners are widely used in the aircraft industry, and service experience shows that for structures where shear loading of the joints is significant, like skin splices, fuselage joints or spar ...High strength threaded fasteners are widely used in the aircraft industry, and service experience shows that for structures where shear loading of the joints is significant, like skin splices, fuselage joints or spar caps-web attachments, more cracks are initiated and grow from the edges of the fastener holes than from features like fillets radii and corners or from large access holes. The main causes of this cracking are the stress concentrations introduced by the fastener holes and by the threaded fasteners themselves, with the most common damage site being at the edge of the fastener holes. Intuitively, it is easy to visualize that after the crack initiation, during the growth stages, some of the load transferred initially by the fastener at the cracked hole will decrease, and it will be shed to the adjacent fasteners that will carry higher loads than in uncracked condition. Using currently available computer software, the method presented in this paper provides a relatively quick and quantitatively defined solution to account for the effects of crack length on the fastener loads transfer, and on the far field and bypass loads at each fastener adjacent to the crack. At each location, these variations are determined from the 3-dimensional distribution of stresses in the joint, and accounting for secondary bending effects and fastener tilt. Two cases of a typical skins lap splice with eight fasteners in a two rows configuration loaded in tension are presented and discussed, one representative for wing or fuselage skins configurations, and the second case representative for cost effective laboratory testing. Each case presents five cracking scenarios, with the cracks growing from approx. 0.03 inch to either the free edge, next hole or both simultaneously.展开更多
A new continuum damage mechanics model for fretting fatigue life prediction is established. In this model, the damage evolution rate is described by two kinds of quantities. One is associated with the cyclic stress ch...A new continuum damage mechanics model for fretting fatigue life prediction is established. In this model, the damage evolution rate is described by two kinds of quantities. One is associated with the cyclic stress characteristics obtained by the finite element (FE) analysis, and the other is associated with the material fatigue property identified from the fatigue test data of standard specimens. The wear is modeled by the energy wear law to simulate the contact geometry evolution. A two-dimensional (2D) plane strain FE implementation of the damage mechanics model and the energy wear model is presented in the platform of ABAQUS to simulate the evolutions of the fatigue damage and the wear scar. The effect of the specimen thickness is also investigated. The predicted results of the crack initiation site and the fretting fatigue life agree well with available experimental data. Comparisons are made with the critical plane Smith- Watson-Topper (SWT) method.展开更多
Failure analysis and fatigue life prediction are very important in the design procedure to assure the safety and reliability of rubber components. The fatigue life of a railway elastomeric pad is predicted by combinin...Failure analysis and fatigue life prediction are very important in the design procedure to assure the safety and reliability of rubber components. The fatigue life of a railway elastomeric pad is predicted by combining the test of material properties and finite element analysis (FEA). The specially developed chloroprene rubber material’s fatigue life equation is acquired based on uniaxial tensile test and fatigue life tests performed on the dumbbell specimens of the chloroprene rubber. The same chloroprene rubber was developed at Indian Rubber Manufacturer’s Research Association, Thane. The strain distribution contours and the maximum total principal strains of the elastomeric pad at different compressive loads are obtained using finite element analysis method. The software used for the FEA was ANSYS. The three parameter nonlinear hyperelastic Mooney-Rivlin Model and plane 182 elements were used for finite element analysis. The critical region cracks prone to arise are obtained and analysed. Then the maximum first principal elastic strain was used as the fatigue damage parameter, which is substituted in the chloroprene rubber’s fatigue life equation, to predict the fatigue life of an elastomeric pad in the number of cycles at different compressive loads. The results were compared with the technical requirements given by Indian Railway’s Research Designs and Standards Organization. These requirements were achieved up to certain extents. The results were also compared with the data available in the literature and a similarity was observed between the results acquired and literature data. In short, the proposed fatigue life prediction method can shorten the product design cycle, decrease the design and product cost remarkably and improve the quality of an elastomeric pad.展开更多
The application of the linear guideways is very extensive, such as automation equipment, heavy-duty carry equipment, heavy-cut machining tool, CNC grinding machine, large-scale planning machine and machining center wi...The application of the linear guideways is very extensive, such as automation equipment, heavy-duty carry equipment, heavy-cut machining tool, CNC grinding machine, large-scale planning machine and machining center with the demand of high rigidity and heavy load. By means of the study of contact behavior between the roller/guideway and roller/slider, roller type linear guideways can improve the machining accuracy. The goal of this paper is to construct the fatigue life model of the linear guideway, with the help of the contact mechanics of rollers. In beginning, the analyses of the rigidity of a single roller compressed between guideway and slider was conducted. Then, the normal contact pressure of linear guideways was obtained by using the superposition method, and verified by the FEM software (ANSYS workbench). Finally, the bearing life theory proposed by Lundberg and Palmgren was used to describe the contact fatigue life.展开更多
The advantage of built-up sleeved backup roll was described. Based on the stress distribution analysis and simulation for the built-up sleeved backup roll by using finite element method, the effects of roll sleeve thi...The advantage of built-up sleeved backup roll was described. Based on the stress distribution analysis and simulation for the built-up sleeved backup roll by using finite element method, the effects of roll sleeve thickness and shrink range on the stress-strain field were studied. Finally, based on the methodology and strategy of the fatigue analysis, fatigue life of backup roll was estimated by using the stress-strain data obtained through finite element simulation. The results show that roll sleeve thickness and shrink range have a great influence on sleeve stress distribution of built-up sleeved roll. Under the circumstance of ensuring transferring enough torque, the shrink range should be kept small. However, thicker roll sleeve has longer roll service life when the shrink range is constant.展开更多
This paper quantitatively evaluated the fatigue life of concrete around the air-water boundary layer of bridge piers located in inland rivers,considering the long-term climate.The paper suggests a method to predict th...This paper quantitatively evaluated the fatigue life of concrete around the air-water boundary layer of bridge piers located in inland rivers,considering the long-term climate.The paper suggests a method to predict the low-cycle fatigue life by demonstrating a thermal-fluid-structural analysis of bridge pier concrete according to long-term climate such as temperature,velocity and pressure of air and water in the process of freezing and thawing in winter.In addition,it proposes a reinforcing method to increase the life of damaged piers and proves the feasibility of the proposed method with numerical comparison experiment.展开更多
The solder joint reliability of a 0.5mm lead pitch, 240-pin quad flat package(QFP) was studied by nonlinear finite element analysis(FEA). The stress/strain distributions within the solder joints and the maximum plas...The solder joint reliability of a 0.5mm lead pitch, 240-pin quad flat package(QFP) was studied by nonlinear finite element analysis(FEA). The stress/strain distributions within the solder joints and the maximum plastic strain range of the solder joints were determined. Based on the calculated maximum plastic strain range the thermal fatigue life of the solder joints was calculated using Coffin-Manson equation. The influences of shape parameters including volume of solder joint, pad size and stand-off on the thermal fatigue life of the solder joints were also studied. The results show that the stress and strain distribution in the solder joint are not uniform; the interface between the lead and the solder joint is the high stress and strain region; the maximum stress and stain occur at the topmost point where the solder joint intersects with the inner side of the lead. The solder joint cracks should occur firstly at this point and propagate along the interface between the solder and the lead. The solder joint with the pad size of 1.25mm×0.35mm, the stand-off of 0.02mm and the solder volume of 0.026mm^3 has longer fatigue life than that of any others. These optimal parameters have been applied in practice to assemble the 240-pin, 0.5mm pitch QFP.展开更多
With the rapid development of the steel industry, to keep pace with the current trend of high speed, continuous, and large-scale production that focuses on automation and high levels of efficiency, many state-owned st...With the rapid development of the steel industry, to keep pace with the current trend of high speed, continuous, and large-scale production that focuses on automation and high levels of efficiency, many state-owned steel companies are being equipped with oil film bearings. Through long-term on-spot inspection and research on the fatigue failure of oil film bearing, three segments of annulated fatigue breakage were found axially along the inner surface of the bearing sleeve. In order to elucidate the reason for the three-segment annulated damage under rolling load, numerical boundary element method was adopted to analyze the contact behaviors between the sleeve and rollneck. Failure mechanism was discussed in detail, the distributions of contact stress were analyzed, and the service lives of the sleeve for different positions on the inner surface were quantitatively described, which provided an effective means to decrease wear and adhesive damage of the sleeve and to increase the load capacity of oil film bearing and its service life as well.展开更多
Fatigue failures of driveline and suspension notched components for ground vehicles under multiaxial loading conditions are common, since most of those components are subjected to complex multiaxial loadings in servic...Fatigue failures of driveline and suspension notched components for ground vehicles under multiaxial loading conditions are common, since most of those components are subjected to complex multiaxial loadings in service. A computational fatigue analysis methodology has been proposed here for performing multiaxial fatigue life prediction for notched components using analytical and numerical methods. The proposed multiaxial fatigue analysis methodology consists of an elastic-plastic stress/strain model and a multiaxial fatigue damage parameter. Results of the proposed multiaxial fatigue analysis methodology are compared to sets of experimental data published in the literature to verify the prediction capability of the elastic-plastic stress/strain model and the multiaxial fatigue damage parameter. Based on the comparison between calculated results and experimental data, it is found that the multiaxial elastic-plastic stress/strain model correlates well with experimental strain data for SAE 1070 steel notched shafts subjected to several non-proportional load paths. In addition, the proposed fatigue damage parameter is found to correlate reasonably well with experimental fatigue data of SAE 1045 steel notched shafts subjected to proportional and non-proportional loadings.展开更多
This study presents an investigation on the fatigue analysis of four types of details on orthotropic steel decks(OSDs)for a cable-stayed super-wide steel box girder bridge based on finite-element analysis(FEA)with veh...This study presents an investigation on the fatigue analysis of four types of details on orthotropic steel decks(OSDs)for a cable-stayed super-wide steel box girder bridge based on finite-element analysis(FEA)with vehicle transverse distribution model(VTDM).A high-fidelity 3D FE model verified by the static load test is established to satisfy the fatigue analysis accuracy.The stress behavior of super-wide steel box girders under the vehicle load at different lane locations is investigated.Then,considering the effect of VTDM,the fatigue life analysis of four typical details is performed using the Miner cumulative damage rule.The results show that the vehicle transverse location has a great influence on the stress behavior of details with sharp influence surface,and the stress ranges in the outermost lane are larger than those in other lanes,indicating that the details of OSD in the outermost lane are prone to fatigue.The fatigue life analysis indicates that the diaphragm cutout is more prone to fatigue than other details,which should be carefully treated in bridge maintenance.展开更多
On the basis of the statistical characteristics of fatigue cumulative damageand its critical value, a new dynamic interference model for reliability analysis is presented. Because the nonlinearity of fatigue damage ac...On the basis of the statistical characteristics of fatigue cumulative damageand its critical value, a new dynamic interference model for reliability analysis is presented. Because the nonlinearity of fatigue damage accumulation is taken into account,this model is able to predict the fatigue reliability for random spectrum loadingconveniently. To verify the predicted results, a special fatigue expenment, in which thenumber of specimen is up to 101, is conducted using a fighter spectrum loading. It isshown that the new model is reliable, practicable and better than existing models.展开更多
文摘A fatigue damage model is developed for evaluating accumulative fatigue damage of dumpers. The loading spectrums acted on dumpers are created according to measured strain data in field. The finite element analysis is carried out for assessing stress distribution and strength characteristics of dumpers. Fatigue damage indexes and service life are calculated by a modified Palmgren-Miner rule. The investigation shows that fatigue notch factor has a significant influence on the calculation of fatigue damage of dumpers.
基金Supports provided by Aviation Basic Science Foundation(00B53010)Aerospace Science Foundation(N3CH0502)Shaanxi Province Natural Science Foundation(N3CS0501)are gratefully appreciated.
文摘Reliability analysis methods based on the linear damage accumulation law (LDAL) and load-life interference model are studied in this paper. According to the equal probability rule, the equivalent loads are derived, and the reliability analysis method based on load-life interference model and recurrence formula is constructed. In conjunction with finite element analysis (FEA) program, the reliability of an aero engine turbine disk under low cycle fatigue (LCF) condition has been analyzed. The results show the turbine disk is safety and the above reliability analysis methods are feasible.
文摘High strength threaded fasteners are widely used in the aircraft industry, and service experience shows that for structures where shear loading of the joints is significant, like skin splices, fuselage joints or spar caps-web attachments, more cracks are initiated and grow from the edges of the fastener holes than from features like fillets radii and corners or from large access holes. The main causes of this cracking are the stress concentrations introduced by the fastener holes and by the threaded fasteners themselves, with the most common damage site being at the edge of the fastener holes. Intuitively, it is easy to visualize that after the crack initiation, during the growth stages, some of the load transferred initially by the fastener at the cracked hole will decrease, and it will be shed to the adjacent fasteners that will carry higher loads than in uncracked condition. Using currently available computer software, the method presented in this paper provides a relatively quick and quantitatively defined solution to account for the effects of crack length on the fastener loads transfer, and on the far field and bypass loads at each fastener adjacent to the crack. At each location, these variations are determined from the 3-dimensional distribution of stresses in the joint, and accounting for secondary bending effects and fastener tilt. Two cases of a typical skins lap splice with eight fasteners in a two rows configuration loaded in tension are presented and discussed, one representative for wing or fuselage skins configurations, and the second case representative for cost effective laboratory testing. Each case presents five cracking scenarios, with the cracks growing from approx. 0.03 inch to either the free edge, next hole or both simultaneously.
基金supported by the National Natural Science Foundation of China(No.11002010)
文摘A new continuum damage mechanics model for fretting fatigue life prediction is established. In this model, the damage evolution rate is described by two kinds of quantities. One is associated with the cyclic stress characteristics obtained by the finite element (FE) analysis, and the other is associated with the material fatigue property identified from the fatigue test data of standard specimens. The wear is modeled by the energy wear law to simulate the contact geometry evolution. A two-dimensional (2D) plane strain FE implementation of the damage mechanics model and the energy wear model is presented in the platform of ABAQUS to simulate the evolutions of the fatigue damage and the wear scar. The effect of the specimen thickness is also investigated. The predicted results of the crack initiation site and the fretting fatigue life agree well with available experimental data. Comparisons are made with the critical plane Smith- Watson-Topper (SWT) method.
文摘Failure analysis and fatigue life prediction are very important in the design procedure to assure the safety and reliability of rubber components. The fatigue life of a railway elastomeric pad is predicted by combining the test of material properties and finite element analysis (FEA). The specially developed chloroprene rubber material’s fatigue life equation is acquired based on uniaxial tensile test and fatigue life tests performed on the dumbbell specimens of the chloroprene rubber. The same chloroprene rubber was developed at Indian Rubber Manufacturer’s Research Association, Thane. The strain distribution contours and the maximum total principal strains of the elastomeric pad at different compressive loads are obtained using finite element analysis method. The software used for the FEA was ANSYS. The three parameter nonlinear hyperelastic Mooney-Rivlin Model and plane 182 elements were used for finite element analysis. The critical region cracks prone to arise are obtained and analysed. Then the maximum first principal elastic strain was used as the fatigue damage parameter, which is substituted in the chloroprene rubber’s fatigue life equation, to predict the fatigue life of an elastomeric pad in the number of cycles at different compressive loads. The results were compared with the technical requirements given by Indian Railway’s Research Designs and Standards Organization. These requirements were achieved up to certain extents. The results were also compared with the data available in the literature and a similarity was observed between the results acquired and literature data. In short, the proposed fatigue life prediction method can shorten the product design cycle, decrease the design and product cost remarkably and improve the quality of an elastomeric pad.
文摘The application of the linear guideways is very extensive, such as automation equipment, heavy-duty carry equipment, heavy-cut machining tool, CNC grinding machine, large-scale planning machine and machining center with the demand of high rigidity and heavy load. By means of the study of contact behavior between the roller/guideway and roller/slider, roller type linear guideways can improve the machining accuracy. The goal of this paper is to construct the fatigue life model of the linear guideway, with the help of the contact mechanics of rollers. In beginning, the analyses of the rigidity of a single roller compressed between guideway and slider was conducted. Then, the normal contact pressure of linear guideways was obtained by using the superposition method, and verified by the FEM software (ANSYS workbench). Finally, the bearing life theory proposed by Lundberg and Palmgren was used to describe the contact fatigue life.
基金Project(E2010001155) supported by the Natural Science Foundation of Hebei Province, China
文摘The advantage of built-up sleeved backup roll was described. Based on the stress distribution analysis and simulation for the built-up sleeved backup roll by using finite element method, the effects of roll sleeve thickness and shrink range on the stress-strain field were studied. Finally, based on the methodology and strategy of the fatigue analysis, fatigue life of backup roll was estimated by using the stress-strain data obtained through finite element simulation. The results show that roll sleeve thickness and shrink range have a great influence on sleeve stress distribution of built-up sleeved roll. Under the circumstance of ensuring transferring enough torque, the shrink range should be kept small. However, thicker roll sleeve has longer roll service life when the shrink range is constant.
基金the National Program on Key Science Research of the DPR of Korea.(Grant No.0305014-01)。
文摘This paper quantitatively evaluated the fatigue life of concrete around the air-water boundary layer of bridge piers located in inland rivers,considering the long-term climate.The paper suggests a method to predict the low-cycle fatigue life by demonstrating a thermal-fluid-structural analysis of bridge pier concrete according to long-term climate such as temperature,velocity and pressure of air and water in the process of freezing and thawing in winter.In addition,it proposes a reinforcing method to increase the life of damaged piers and proves the feasibility of the proposed method with numerical comparison experiment.
基金Project(02336060) supported by the Natural Science Foundation of Guangxi Province , China
文摘The solder joint reliability of a 0.5mm lead pitch, 240-pin quad flat package(QFP) was studied by nonlinear finite element analysis(FEA). The stress/strain distributions within the solder joints and the maximum plastic strain range of the solder joints were determined. Based on the calculated maximum plastic strain range the thermal fatigue life of the solder joints was calculated using Coffin-Manson equation. The influences of shape parameters including volume of solder joint, pad size and stand-off on the thermal fatigue life of the solder joints were also studied. The results show that the stress and strain distribution in the solder joint are not uniform; the interface between the lead and the solder joint is the high stress and strain region; the maximum stress and stain occur at the topmost point where the solder joint intersects with the inner side of the lead. The solder joint cracks should occur firstly at this point and propagate along the interface between the solder and the lead. The solder joint with the pad size of 1.25mm×0.35mm, the stand-off of 0.02mm and the solder volume of 0.026mm^3 has longer fatigue life than that of any others. These optimal parameters have been applied in practice to assemble the 240-pin, 0.5mm pitch QFP.
基金Item Sponsored by National Natural Science Foundation of China (50575155)
文摘With the rapid development of the steel industry, to keep pace with the current trend of high speed, continuous, and large-scale production that focuses on automation and high levels of efficiency, many state-owned steel companies are being equipped with oil film bearings. Through long-term on-spot inspection and research on the fatigue failure of oil film bearing, three segments of annulated fatigue breakage were found axially along the inner surface of the bearing sleeve. In order to elucidate the reason for the three-segment annulated damage under rolling load, numerical boundary element method was adopted to analyze the contact behaviors between the sleeve and rollneck. Failure mechanism was discussed in detail, the distributions of contact stress were analyzed, and the service lives of the sleeve for different positions on the inner surface were quantitatively described, which provided an effective means to decrease wear and adhesive damage of the sleeve and to increase the load capacity of oil film bearing and its service life as well.
文摘Fatigue failures of driveline and suspension notched components for ground vehicles under multiaxial loading conditions are common, since most of those components are subjected to complex multiaxial loadings in service. A computational fatigue analysis methodology has been proposed here for performing multiaxial fatigue life prediction for notched components using analytical and numerical methods. The proposed multiaxial fatigue analysis methodology consists of an elastic-plastic stress/strain model and a multiaxial fatigue damage parameter. Results of the proposed multiaxial fatigue analysis methodology are compared to sets of experimental data published in the literature to verify the prediction capability of the elastic-plastic stress/strain model and the multiaxial fatigue damage parameter. Based on the comparison between calculated results and experimental data, it is found that the multiaxial elastic-plastic stress/strain model correlates well with experimental strain data for SAE 1070 steel notched shafts subjected to several non-proportional load paths. In addition, the proposed fatigue damage parameter is found to correlate reasonably well with experimental fatigue data of SAE 1045 steel notched shafts subjected to proportional and non-proportional loadings.
基金supported by the National Natural Science Foundation of China(Grant Nos.51778135,52178119)the Distinguished Young Scientists of Jiangsu Province(Grant No.BK20190013)the National Key R&D Program Foundation of China(Grant No.2017YFC0806001).
文摘This study presents an investigation on the fatigue analysis of four types of details on orthotropic steel decks(OSDs)for a cable-stayed super-wide steel box girder bridge based on finite-element analysis(FEA)with vehicle transverse distribution model(VTDM).A high-fidelity 3D FE model verified by the static load test is established to satisfy the fatigue analysis accuracy.The stress behavior of super-wide steel box girders under the vehicle load at different lane locations is investigated.Then,considering the effect of VTDM,the fatigue life analysis of four typical details is performed using the Miner cumulative damage rule.The results show that the vehicle transverse location has a great influence on the stress behavior of details with sharp influence surface,and the stress ranges in the outermost lane are larger than those in other lanes,indicating that the details of OSD in the outermost lane are prone to fatigue.The fatigue life analysis indicates that the diaphragm cutout is more prone to fatigue than other details,which should be carefully treated in bridge maintenance.
文摘On the basis of the statistical characteristics of fatigue cumulative damageand its critical value, a new dynamic interference model for reliability analysis is presented. Because the nonlinearity of fatigue damage accumulation is taken into account,this model is able to predict the fatigue reliability for random spectrum loadingconveniently. To verify the predicted results, a special fatigue expenment, in which thenumber of specimen is up to 101, is conducted using a fighter spectrum loading. It isshown that the new model is reliable, practicable and better than existing models.