Stress intensity factors are calculated along the weld root for load carrying welded joints under shear loading. The value of the stress intensity factor increases towards the weld end points as expected. An extrapola...
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ISBN:
(纸本)9789608810433
Stress intensity factors are calculated along the weld root for load carrying welded joints under shear loading. The value of the stress intensity factor increases towards the weld end points as expected. An extrapolation procedure is suggested for the determination of a weld end point associated stress intensity factor where the stress singularity is no longer of the crack front type. In the experimental part of this research fatigue testing of thin sheet plane and cylindrical specimens was performed. The fatigue cracks initiated at the weld end points. A weld-end life curve has been obtained which is expressed in terms of the weld end stress intensity factor range. The thin sheet results are compared to results of a thick sheet member of a motor truck to discuss the transferability of fatigue data for different geometrical items.
Taking high-performance parabolic steel leaves from serial springs used for the suspension of front axles of trucks as an example, the present paper focuses on the influence of the material, the heat treatment and the...
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ISBN:
(纸本)9789608810433
Taking high-performance parabolic steel leaves from serial springs used for the suspension of front axles of trucks as an example, the present paper focuses on the influence of the material, the heat treatment and the stress peening processes on the microstrucure, the surface properties (residual stresses, micro- and macro-hardness, roughness, decarburization zone and percentage) and, especially, the fatigue life of parabolic leaf springs. Hardnessess of the leaf core and surface, roughness profiles and residual stress profiles of both the stress peened and untreated leaf surfaces were determined to quantify the influence of the applied heat treatment and stress peening. Analytical calculations based on the FKM guideline were performed to evaluate every above mentioned fatigue life influencing factor. Comparison of the analytical results with the corresponding experimentally determined ones reveal the accuracy of the current theoretical tools.
An advanced methodology for integrity monitoring of structures based on Acoustic Emission and follow-up non-destructive testing has been developed and verified in laboratory1, 2. Current research activities3 focus on ...
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ISBN:
(纸本)9789608810433
An advanced methodology for integrity monitoring of structures based on Acoustic Emission and follow-up non-destructive testing has been developed and verified in laboratory1, 2. Current research activities3 focus on application to large-scaled transportation products (ships, road tankers, railway cars). Monitoring during operation enables early detection of degradations (corrosion, fatigue cracks) and condition-based maintenance. Consequently, transportation of (hazardous) goods will become safer and economically compared to conventional time-based inspections. Main features of the developed monitoring technique are: (a) identification of degradation using FEA based on load data, (b) use of advanced and intrinsically safe AE equipment, redesigned for application at transport products, identification of degradation mechanisms and separation of background noises, (c) on-line acquisition, assessment and storage of AE signals, and (d) follow-up non-destructive testing for verification of degradations. The developed monitoring technique and its validation on test objects are presented. AE signals are assessed to identify and locate degradation mechanisms. The results reveal capability and accuracy of the proposed methodology in the large-scale application field.
In many applications, the transmitted power by a gearbox is fluctuating strongly. For example, in wind energy converters the rotor torque depends on the wind velocity and therefore varyies over a wide range, whereas t...
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Wear and surface fatigue of elastohydrodynamic contacts are strongly affected by asperity collisions. Therefore, the transition from the full to the mixed lubrication regime is of particular interest. In order to quan...
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Wear and surface fatigue of elastohydrodynamic contacts are strongly affected by asperity collisions. Therefore, the transition from the full to the mixed lubrication regime is of particular interest. In order to quantify this transition, the solid contact time percentage is introduced in this study. It is obtained by an experimental technique based on a two-disk test rig that enables to determine whether asperity collisions occur or not. The influence of the surface finish on the elastohydrodynamic performance is investigated using several disk pairs with the same composite roughness but different surface micro-topography. Results are evaluated using both the solid contact time percentage and the friction coefficient. It is shown that significant improvement on the tribological behaviour can be achieved by properly selecting the surface finish. In this way, the need for special surface texturing can be eliminated in many cases.
Based on Dankert's et al. [1] initial model for the elastic-plastic evaluation of fatigue crack growth in sheets providing elliptical notches, a generalized procedure enabling an improved evaluation of the effecti...
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Based on Dankert's et al. [1] initial model for the elastic-plastic evaluation of fatigue crack growth in sheets providing elliptical notches, a generalized procedure enabling an improved evaluation of the effective ranges of the crack driving force (i.e. the J-Integral) as well as the application to arbitrary notched components has been developed [2], The present paper presents the basic topics of the calculation model as well as its verification using experimental results from notched specimens with various notch shapes subjected to cyclic loading with various load ratios.
During the last decades, the power rating and consequently the size of wind energy converters (WEC's) follow an increasing trend. The resulting demand for higher load carrying capacity and transmission ratios is e...
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During the last decades, the power rating and consequently the size of wind energy converters (WEC's) follow an increasing trend. The resulting demand for higher load carrying capacity and transmission ratios is expected to rise since larger wind turbines imply lower cost per unit power and allow for a more efficient land use. Following this trend, a new design of a power transmission system for power ratings greater then 1 MW is proposed in the current study. It mainly consists of a common ring gear double stage planetary gearbox, assembled inside two large diameter rolling bearings (also known as slewing bearings) with internal gearing. The rotor hub is directly connected to the inner ring of the outer bearing. Apart from omitting the rotor shaft, this design promotes power splitting, resulting in a compact and lightweight construction.
This paper describes part of a design validation study of a carbon-epoxy sandwich machine component in the form of a curved beam which is subjected to high angular accelerations (more than 5000 s(-2)) during service. ...
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This paper describes part of a design validation study of a carbon-epoxy sandwich machine component in the form of a curved beam which is subjected to high angular accelerations (more than 5000 s(-2)) during service. The study is based on the comparison of the results of a static loading experiment and modal testing with the corresponding finite element predictions made by using commercial software (I-DEAS). The close correspondence observed between the experimental and the numerical results, despite the incompatibility between the solid and the shell elements used in the finite element analysis, has been discussed from the point of view of the degree of mesh refinement, the simplicity of the design and the quality of fabrication of the component.
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