Effect of the ageing on the dissipative properties of getinacks subjected to repeated static loading

2014 ◽  
Vol 11 (6) ◽  
pp. 589-596
Author(s):  
Valesyan Shant
Keyword(s):  
Experimental Data ◽  
Experimental Investigation ◽  
Temperature Field ◽  
Energy Dissipation ◽  
Hysteresis Loop ◽  
Static Loading ◽  
Applied Load ◽  
Effect Of Temperature ◽  
Loading And Unloading

The effect of ageing on the dissipative properties of getinacks subjected to repeated static loading has been investigated. Specimens were tested at the age of 1, 4, and 8 years. The approximation of experimental data is done, and the energy of dissipation is calculated. Based on the investigation of getinacks manufactured by the technology of regulated thermo-pressing, this technology can be recommended for the manufacturing of appropriate products.The results of experimental investigation of the effect of temperature field on the dissipative properties of layered getinacks widely applicable in electrical manufacturing, electronics and microelectronics are considered in this paper. The approximation of the experimentally obtained dependences between σ and ε for the loading (→) and unloading (←) parts of the hysteresis loop are calculated and plotted. The factor of energy dissipation is defined. Estimated that the temperature field affects the dissipative properties of the layered getinacks and that effect is depending on the value of applied load cyclically acting on the material.

An experimental approach on energy dissipation of bolted joints using a modified oscillator device

2021 ◽  
pp. 107754632110079
Author(s):  
Yikun Li ◽  
Zhiming Hao ◽  
Qiang Du ◽  
Minglu Xing ◽  
Linlong Dou ◽  
...  
Keyword(s):  
Experimental Data ◽  
Surface Roughness ◽  
Energy Dissipation ◽  
Hysteresis Loop ◽  
Experimental Approach ◽  
Bolted Joints ◽  
Joint Damping ◽  
Series Type ◽  
Stability And Accuracy ◽  
Parallel Type

A modified and simplified oscillator device is designed and manufactured to investigate the effects of contact roughness and bolt arrangements on energy dissipation caused by joint damping. Three types of surface roughness and five different bolt arrangements are discussed. Identification of Iwan model based on experimental data is carried out. It is indicated that rough surface dissipates more energy than smooth one. Specimens with more bolts dissipate relatively more energy. When bolt number is consistent, the series type dissipates more energy than the parallel type. Experimental data show a good stability and accuracy of the proposed oscillator device. The identified Iwan model provides a good conformity with the reconstructed hysteresis loop. The four-parameter Iwan model can well describe the damping property of joints with different surface roughness and bolt arrangements.

scholarly journals Fracture Characteristics and Fatigue Damage of Noncoplanar Fractured Rocklike Specimens under Uniaxial Graded Cyclic Loading and Unloading

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Gui-cheng He ◽  
Wen-yuan Wu ◽  
Yun Wang ◽  
Yong-ming Xue ◽  
Bing Dai ◽  
...  
Keyword(s):  
Elastic Modulus ◽  
Energy Dissipation ◽  
Cyclic Loading ◽  
Hysteresis Loop ◽  
Fatigue Damage ◽  
Damping Ratio ◽  
Fracture Characteristics ◽  
Cyclic Loading And Unloading ◽  
Loading And Unloading ◽  
Limit Stress

To study the fracture characteristics and fatigue damage of fractured rock masses, noncoplanar fractured rocklike specimens prepared using cement mortar were used for a graded cyclic loading–unloading test. The results showed that the two ends of the horizontal crack were the main stress concentration areas, and they inhibited crack initiation of the inclined fracture. With increasing crack inclination, the inhibitory effect became more obvious. Under the condition that the lower limit stress is constant, as the upper limit stress increases, energy dissipation of the specimen increases, becoming relatively stable in each stage of the cycle. With increasing crack inclination, the increase in the energy dissipation value decreases. Specimens with large changes in the shape of their hysteresis loop tend to exhibit large fluctuations in the elastic modulus. As the loading progressed, the elastic modulus exhibited a downward trend, and the damping ratio tended to be stable. The change in the damping ratio is affected by the dynamic elastic modulus and area of the hysteresis loop. Based on the Weibull probability distribution function, the evolution curve of the damage variable of the specimen can be obtained. This curve reflects the trend of the damage change of the rocklike specimens under various levels of cyclic loading and unloading.

Determination of the area of mechanical hysteresis loop using mathematical models

2020 ◽  
Vol 86 (5) ◽  
pp. 59-64
Author(s):  
G. D. Petrushin ◽  
A. G. Petrushina
Keyword(s):  
Energy Dissipation ◽  
Mathematical Models ◽  
Hysteresis Loop ◽  
Direct Method ◽  
Relative Energy ◽  
Test Machine ◽  
Mechanical Hysteresis ◽  
Damped Oscillations ◽  
Loading And Unloading

A method of the hysteresis loop relates to the direct methods for determination of the energy dissipation and studying the inelasticity in the material. The method is based on the direct formation of the mechanical hysteresis loop by static loading and unloading of the sample and measuring of the corresponding deformations. The relative energy dissipation is defined as the ratio of the hysteresis loop area to the elastic energy corresponding to the maximum amplitude of strain. Construction of the hysteresis loop is performed on the installation «torsional pendulum for determination of the mechanical properties of materials» which can work as a device for measuring internal energy dissipation by damped oscillations, and as a precision torsion test machine using a deforming device. The aim of this work is to determine the area of the static hysteresis loop through the choice of the mathematical models of loading and unloading curves with subsequent numerical integration using the ordinate values at equidistant points. The analysis of using polynomials of the second or third degree was carried out according to the criterion of the smallest sum of squared deviations between the empirical and calculated values of the function. The experimentally obtained coordinates of the points of the deformation diagram of the sample during loading and unloading were used as initial data for estimation of regression coefficients in polynomial equations. A distinctive feature of the proposed method is that analytical dependences between stresses and strains obtained by N. N. Davidenkov and containing hard-to-determine geometric parameters of the loop, which must be pre-set from the known values of the logarithmic decrement of oscillations obtained from the experiment are not used in the developed method to calculate the area of the static hysteresis loop. It is shown that a comparative assessment of the relative energy scattering in the ferrite gray iron performed by the direct method of determining the area of the mechanical hysteresis loop at different amplitudes of shear deformation, is in good agreement with the data obtained by the indirect method of damped oscillations on an installation of the similar class.

Sign in / Sign up

Export Citation Format

Share Document