Study on temperature rise distribution of contact surface under cyclic load

2020 ◽  
Vol 235 (1) ◽  
pp. 138-148
Author(s):  
Ling Li ◽  
Haifei Tian ◽  
Qiangqiang Yun ◽  
Wei Chu
Keyword(s):  
Contact Surface ◽  
Temperature Rise ◽  
Cyclic Load ◽  
Thermal Structure ◽  
Constant Load ◽  
Contact Center ◽  
Tangential Load ◽  
Cycle Number ◽  
Load Amplitude ◽  
Depth Direction

A large amount of heat is generated during the friction of joint surfaces, which has a significant influence on the contact characteristics of surfaces, causing deformation or failure of key components. A two-dimensional friction-thermal structure coupling contact model of cylinder/plane was established in ABAQUS. The effects of roughness under different fractal parameters, tangential load amplitude and cycle number on the temperature rise distribution of a contact surface under normal cyclic loading were studied. The results show that with the increase of roughness and tangential load amplitude, the area of thermal effect becomes more obvious and the temperature rise of the contact surface increases. It is also found that the heat affected zone is mainly distributed near the surface of the contact area with a high-temperature field generated, while the temperature rise amplitude decreases gradually along the depth direction. In addition, the contact surface nodes have a similar temperature rise distribution process and the farther away from the contact center ( x = 0.3 mm), the smaller the temperature rise, which is consistent with the simulation results of the published literature. For the same tangential load amplitude, the surface temperature rise amplitude under the normal cyclic load is lower than that of the normal constant load. The temperature rise of the surface increases with the increase of the number of fretting cycles.

Effects of Constant Load on Autograft Healing Compared with Those of Cyclic Load

1994 ◽  
pp. 347-352
Author(s):  
Takeshi Muneta ◽  
Shunich Murakami ◽  
Youichi Ezura ◽  
Shintaro Asahina ◽  
Kazuo Takakuda ◽  
...  
Keyword(s):  
Cyclic Load ◽  
Constant Load

Application of a Cyclic Degradation Model for Pore Pressure Accumulation in Loose Sands and Silts Subjected to Dynamic Loading

2018 ◽  
Vol 12 (05) ◽  
pp. 1850014
Author(s):  
A. Juneja ◽  
A. K. Mohammed-Aslam
Keyword(s):  
Pore Pressure ◽  
Cyclic Load ◽  
Load Cycle ◽  
Ultimate State ◽  
Degradation Model ◽  
Load Amplitude ◽  
Low Load ◽  
Yield Loci ◽  
Cyclic Degradation ◽  
Stress Dependent

Most cyclic soil models which are used to estimate strain and pore pressure accumulations, are soil specific and, often evaluate the accumulation model either as a function of the number of load cycles or they tend to utilize parameters which can only be obtained by using detailed laboratory tests. This paper attempts to enhance the capabilities of a simple plasticity model which can approximate the trend of pore pressure accumulation. This function uses a stress dependent degradation parameter which allows the yield loci to adjust and reduce its size at the end of each load cycle. The cyclic degradation model which was originally developed for clays, was adapted for sands and silts in this work with the use of two new parameters. The model was tested by using the cyclic triaxial data of three non-plastic soils. These samples were subjected to cyclic load amplitudes which are normally used in most seismic studies. The modified degradation model could predict fairly well the pore pressure accumulation in high-load amplitude tests but lead to over-prediction in low-load amplitude tests, unless the function was allowed to taper off at large cycles. Notwithstanding the above, the above cyclic model using the degraded yield surface, was incapable of correctly predicting the stress paths which were close to the sample’s ultimate state as it failed to permit phase transformation which is generally observed in sands and silts.

A Microcontact Non-Gaussian Surface Roughness Model Accounting for Elastic Recovery

2008 ◽  
Vol 75 (3) ◽  
Author(s):  
Jeng Luen Liou ◽  
Jen Fin Lin
Keyword(s):  
Probability Density Function ◽  
Probability Density ◽  
Density Function ◽  
Contact Surface ◽  
Elastic Recovery ◽  
Normal Load ◽  
Theoretical Method ◽  
Constant Load ◽  
Plasticity Index ◽  
Non Gaussian

Most statistical contact analyses assume that asperity height distributions (g(z*)) follow a Gaussian distribution. However, engineered surfaces are frequently non-Gaussian with the type dependent on the material and surface state being evaluated. When two rough surfaces experience contact deformations, the original topography of the surfaces varies with different loads, and the deformed topography of the surfaces after unloading and elastic recovery is quite different from surface contacts under a constant load. A theoretical method is proposed in the present study to discuss the variations of the topography of the surfaces for two contact conditions. The first kind of topography is obtained during the contact of two surfaces under a normal load. The second kind of topography is obtained from a rough contact surface after elastic recovery. The profile of the probability density function is quite sharp and has a large peak value if it is obtained from the surface contacts under a normal load. The profile of the probability density function defined for the contact surface after elastic recovery is quite close to the profile before experiencing contact deformations if the plasticity index is a small value. However, the probability density function for the contact surface after elastic recovery is closer to that shown in the contacts under a normal load if a large initial plasticity index is assumed. How skewness (Sk) and kurtosis (Kt), which are the parameters in the probability density function, are affected by a change in the dimensionless contact load, the initial skewness (the initial kurtosis is fixed in this study) or the initial plasticity index of the rough surface is also discussed on the basis of the topography models mentioned above. The behavior of the contact parameters exhibited in the model of the invariant probability density function is different from the behavior exhibited in the present model.

Loading–unloading contact analysis of a fractal rough surface with functional gradation

2021 ◽  
pp. 146442072110621
Author(s):  
Tamonash Jana ◽  
Anirban Mitra ◽  
Prasanta Sahoo
Keyword(s):  
Rough Surface ◽  
Contact Force ◽  
Contact Area ◽  
Contact Surface ◽  
Functionally Graded ◽  
The Other ◽  
Fractal Rough Surface ◽  
Depth Direction ◽  
Fractal Roughness ◽  
Rough Surface Contact

The present paper deals with a finite-element-based static loading–unloading analysis of a functionally graded rough surface contact with fractal characteristics. Two different gradation models, namely elastic and plastic gradations, are adopted. In these models, one out of yield strength and Young's modulus is varied spatially according to exponential functions, while the other is kept constant. In both these material models, separate inhomogeneity parameters control the variation of material properties. The gradation is such that throughout the top of the rough surface properties remain constant with variations in the depth direction being controlled by the above-mentioned parameters. Different fractal surfaces with different levels of roughness (governed by the values of fractal dimension and fractal roughness) have been analysed. The influence of the gradation parameters on the contact properties, viz. contact force, contact area, contact stress, etc., are investigated for both loading and unloading phases. It was found that for most of the loading phase, higher elastic, as well as plastic gradation parameter, causes higher contact force and contact area. However, in the case of the unloading of elastically graded surfaces, this trend is not maintained throughout. For the cases, where a substantial amount of yielding takes place during loading near the contact surface, the resulting contact area is found to be higher for the unloading phase in comparison with the same during the loading phase. The trend of plastic yielding at the vicinity of the contact surface is studied for varying gradation parameters. It is observed that the higher volume of yielded material is obtained for the higher value of elastic gradation parameter. On the other hand, the higher value of plastic gradation parameter causes more yielding to take place at the vicinity of the contact surface. Additionally, the effect of gradation on the energy dissipation due to plasticity after complete unloading is explored in detail.

A Direct Method on the Evaluation of Ratchet Limit

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
Haofeng Chen ◽  
Alan R. S. Ponter
Keyword(s):  
Cyclic Load ◽  
Mechanical Load ◽  
Low Cycle Fatigue ◽  
Direct Method ◽  
Numerical Technique ◽  
Load Condition ◽  
Numerical Procedure ◽  
Constant Load ◽  
Inelastic Analysis ◽  
Additional Constant

This paper describes a new linear matching method (LMM) technique for the direct evaluation of the ratchet limit of a structure subjected to a general cyclic load condition, which can be decomposed into cyclic and constant components. The cyclic load history considered in this paper contains multiload extremes to include most complicated practical applications. The numerical procedure uses the LMM state-of-the-art numerical technique to obtain a stable cyclic state of component, followed by a LMM shakedown analysis, to calculate the maximum constant load, i.e., the ratchet limit, which indicates the load carrying capacity of the structure subjected to a cyclic load condition to withstand an additional constant load. This approach is particularly useful in conjunction with the evaluation of the stable cyclic response, which produces the cyclic stresses, residual stresses, and plastic strain ranges for the low cycle fatigue assessment. A benchmark example of a holed plate under the combined action of cyclic thermal load and constant mechanical load is presented to verify the applicability of the new ratchet limit method through a comparison with published results by a simplified method assuming a cyclic load with two extremes. To demonstrate the efficiency and effectiveness of the method for a complicated cyclic load condition with multiload extremes, a composite thick cylinder with a radial opening subjected to cyclic thermal loads and a constant internal pressure is analyzed using the proposed ratchet limit method. Further verification by the ABAQUS step-by-step inelastic analysis demonstrates that the proposed new method provides a general-purpose technique for the evaluation of the ratchet limit and has both the advantages of programming methods and the capacity to be implemented easily within a commercial finite element code Abaqus.

Duration of load and probability of failure in wood. Part II. Constant, ramp, and cyclic loadings

1978 ◽  
Vol 5 (4) ◽  
pp. 515-532 ◽  
Author(s):  
J. D. Barrett ◽  
R. O. Foschi
Keyword(s):  
Cyclic Load ◽  
Constant Load ◽  
Probability Of Failure ◽  
Strength Distribution ◽  
Generalized Model ◽  
Cycle Amplitude ◽  
Short Term Strength ◽  
Wood Part ◽  
Duration Of Load ◽  
Snow Loading

A generalized model for damage accumulation is used to study the probability of failure of a wood member in bending for different load histories. The variability in time-to-fracture corresponding to a given load history is accounted for in the generalized model. Four types of loads are considered: (1) a constant load, (2) a ramp load, (3) a cyclic load of constant cycle amplitude, and (4) a cyclic load of random cycle amplitude. In each case, the probability of failure is studied as a function of the factor [Formula: see text] which, in the design equation, is applied to the 5th percentile of the short-term strength distribution to obtain the design stress. Snow loading is considered as an example of cyclic load with random cycle amplitude.

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