The relationship between dynamic strength and strain rate and damage to rock materials subjected to dynamic cyclic loading

2021 ◽  
Vol 7 (3) ◽  
Author(s):  
Yongqiang Zhou ◽  
Qian Sheng ◽  
Nana Li ◽  
Xiaodong Fu
Keyword(s):  
Cyclic Loading ◽  
Strain Rate ◽  
Dynamic Strength ◽  
Rock Materials ◽  
The Relationship

scholarly journals Strength and Fatigue Properties of Sandstone under Dynamic Cyclic Loading

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Mingming He ◽  
Ning Li ◽  
Yunsheng Chen ◽  
Caihui Zhu
Keyword(s):  
Fatigue Life ◽  
Cyclic Loading ◽  
Mechanical Characteristics ◽  
Stress Amplitude ◽  
Dynamic Strength ◽  
Fatigue Properties ◽  
Loading Frequency ◽  
Strength And Deformation ◽  
Metal Materials ◽  
The Relationship

This paper presents an experimental investigation of strength and fatigue properties of intact sandstone samples subjected to dynamic cyclic loading in the laboratory. Tests were conducted on sandstone samples with loading frequencies ranging in 0.5, 1, 2, and 4 Hz, loading amplitudes of 1, 15, 30, 60, 90, and 120 kN, and loading speeds of 0.5, 1, 2, 4, and 8 kN/s. In this study it was shown that the loading frequency, as well as the amplitude and loading speed, was of great significance and affected the mechanical characteristics of sandstone under dynamic cyclic loading. The fatigue life of sandstone was found to decrease with loading speeds and amplitudes but increase with loading frequencies. It was found that the minimum of the dynamic strength and deformation factor of sandstone was obtained at loading speeds of 2 kN/s but the maximum at loading frequencies of 1 Hz. Finally, it was concluded that the relationship between the fatigue life and loading speed, frequency, and stress amplitude under dynamic cyclic loading would be expressed as theS-Ncurve, which showed that the fatigue characteristic of sandstone was similar to that of metal materials.

Effect of Initial Static Load on the Rate-Sensitive Behavior of Concrete in Compression

2006 ◽  
Vol 326-328 ◽  
pp. 1109-1112
Author(s):  
Dong Ming Yan ◽  
Gao Lin
Keyword(s):  
Strain Rate ◽  
Static Load ◽  
Dynamic Properties ◽  
Concrete Structures ◽  
Dynamic Strength ◽  
Rate Sensitivity ◽  
Static Loads ◽  
Dynamic Loadings ◽  
Strength And Deformation ◽  
The Relationship

Before concrete structures are subjected to dynamic loadings such as earthquake, usually they have already withstood static loads. Accordingly, the study on the strain-rate sensitivity of concrete should also be closely related to the initial static loads that concrete structures experience. But majority of the available documents concerning the dynamic properties of concrete do not take initial static load into consideration. In this study, experiments were carried out to investigate the effect of initial static load on the dynamic strength and deformation characteristics of concrete in compression. A load was initially applied on the specimen at a very low speed to a specified value and then the dynamic load was applied at a high strain rate up to the failure of the specimen. From the test results it was revealed that the initial static load had significant influence on the dynamic strength. The dynamic strength tended to decrease as initial static load increased. An exponential function was proposed to formulate the relationship between the initial static load and the dynamic strength.

scholarly journals Investigation of Deformation Inhomogeneity and Low-Cycle Fatigue of a Polycrystalline Material

2021 ◽  
Vol 11 (6) ◽  
pp. 2673
Author(s):  
Mu-Hang Zhang ◽  
Xiao-Hong Shen ◽  
Lei He ◽  
Ke-Shi Zhang
Keyword(s):  
Cyclic Loading ◽  
Low Cycle Fatigue ◽  
Strain Tensor ◽  
Equivalent Strain ◽  
Differential Entropy ◽  
Strain Components ◽  
Deformation Inhomogeneity ◽  
Standard Deviations ◽  
Number Of Cycles ◽  
The Relationship

Considering the relationship between inhomogeneous plastic deformation and fatigue damage, deformation inhomogeneity evolution and fatigue failure of superalloy GH4169 under temperature 500 °C and macro tension compression cyclic loading are studied, by using crystal plasticity calculation associated with polycrystalline representative Voronoi volume element (RVE). Different statistical standard deviation and differential entropy of meso strain are used to measure the inhomogeneity of deformation, and the relationship between the inhomogeneity and strain cycle is explored by cyclic numerical simulation. It is found from the research that the standard deviations of each component of the strain tensor at the cyclic peak increase monotonically with the cyclic loading, and they are similar to each other. The differential entropy of each component of the strain tensor also increases with the number of cycles, and the law is similar. On this basis, the critical values determined by statistical standard deviations of the strain components and the equivalent strain, and that by differential entropy of strain components, are, respectively, used as fatigue criteria, then predict the fatigue–life curves of the material. The predictions are verified with reference to the measured results, and their deviations are proved to be in a reasonable range.

scholarly journals Coupled Thermomechanical Response Measurement of Deformation of Nickel-Based Superalloys Using Full-Field Digital Image Correlation and Infrared Thermography

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2163
Author(s):  
Krzysztof Żaba ◽  
Tomasz Trzepieciński ◽  
Sandra Puchlerska ◽  
Piotr Noga ◽  
Maciej Balcerzak
Keyword(s):  
Surface Temperature ◽  
Strain Rate ◽  
Rolling Direction ◽  
Image Correlation ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Response Measurement ◽  
Sheet Rolling ◽  
Inconel Alloys ◽  
The Relationship

The paper is devoted to highlighting the potential application of the quantitative imaging technique through results associated with work hardening, strain rate and heat generated during elastic and plastic deformation. The aim of the research presented in this article is to determine the relationship between deformation in the uniaxial tensile test of samples made of 1-mm-thick nickel-based superalloys and their change in temperature during deformation. The relationship between yield stress and the Taylor–Quinney coefficient and their change with the strain rate were determined. The research material was 1-mm-thick sheets of three grades of Inconel alloys: 625 HX and 718. The Aramis (GOM GmbH, a company of the ZEISS Group) measurement system and high-sensitivity infrared thermal imaging camera were used for the tests. The uniaxial tensile tests were carried out at three different strain rates. A clear tendency to increase the sample temperature with an increase in the strain rate was observed. This conclusion applies to all materials and directions of sample cutting investigated with respect to the sheet-rolling direction. An almost linear correlation was found between the percent strain and the value of the maximum surface temperature of the specimens. The method used is helpful in assessing the extent of homogeneity of the strain and the material effort during its deformation based on the measurement of the surface temperature.

Correlation of wear and work in dual pivoted jaw crusher tests

2018 ◽  
Vol 234 (3) ◽  
pp. 334-349
Author(s):  
Juuso Terva ◽  
Kati Valtonen ◽  
Pekka Siitonen ◽  
Veli-Tapani Kuokkala
Keyword(s):  
Flow Stress ◽  
Strain Rate ◽  
Mass Loss ◽  
Lower Amount ◽  
Jaw Crusher ◽  
Rate Dependent ◽  
Sliding Motion ◽  
The Relationship

A laboratory sized jaw crusher with uniform movement of the jaws, the dual pivoted jaw crusher, was used to determine the relationship between wear and work. Wear was concentrated on the jaw plates opposing each other and was measured as mass loss of the specimens. Work was measured directly from the force and displacement of the instrumented jaw, which allowed work to accumulate only from the actual crushing events. The tests were conducted with several jaw geometries and with two motional settings, where the relation of compressive and sliding motion between the jaws was varied. The tests showed that the relation between wear and work was constant in many of the tested cases. In certain tests with larger lateral and faster contact speed, wear occurred at relatively lower amounts of work. This behavior was more definite when the relation of wear and work was investigated using modified Archards wear equation. The results indicate that the lower amount of needed work could stem from the material reaching a dynamic situation, where the flow stress becomes increasingly strain-rate dependent.

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