Effect Of Loading Rate Research Articles

Effect of loading rate on characteristics of cyclic structural adjustment of sandstone granules

During underground coal seam mining, changes in the working face advancement rate can easily affect the compaction state of granules in the collapse zone. This is an important factor in the induction of gas disasters and surface subsidence in mining areas. In this work, a cyclic loading and unloading mechanical test of granules under different loading rates was carried out. The changes in mechanical parameters of the granules at various stages were investigated. It is shown that the strain of each group of specimens under cyclic loading shows an increasing trend and the final strain increases with the loading rate. The input energy of the granules increases under cyclic loading, and under a low loading rate, the compaction force needs to overcome interparticle friction to destroy the relatively stable structure, which results in a need for more energy to achieve the same level of deformation. The acoustic emission ringing counts of each group of granules specimens show an overall increasing trend, with the highest proportion of ringing counts in the first loading stage. The compaction of pores and filling of particles under cyclic loading is a “uniform compaction, stable change, slow adjustment” dynamic process. When the loading is slow, the relative positions of the granule particles in each stress gradient are more adequately adjusted. The results of this study provide important theoretical support for the scientific formulation of gas control strategies and the prevention of surface subsidence in air-mining zones under different mining speeds.

Experimental and Numerical Study of the Uniaxial Compressive Strength of Ice with Initial Fibrous Pore: Effects of Temperature and Loading Rate

Experimental and Numerical Study of the Uniaxial Compressive Strength of Ice with Initial Fibrous Pore: Effects of Temperature and Loading Rate

Atomic-scale investigation on the mechanical behaviors of the γ′/γ′′ co-precipitates compounds in Ni-based superalloys

Atomic-scale investigation on the mechanical behaviors of the γ′/γ′′ co-precipitates compounds in Ni-based superalloys

Room-Temperature Creep Deformation of a Pressure-Resistant Cylindrical Structure Made of Dissimilar Titanium Alloys

The long-term safety of pressure-resistant structures used in deep-sea equipment may be threatened by creep deformation. The creep deformation behavior of a pressure-resistant structure made of different titanium alloys, Ti-6Al-4V and Ti-4Al-2V, at room temperature is investigated in this research. The kinetics and mechanisms underlying creep deformation in these materials is explained by proposing an improved constitutive model considering the effects of stress level, loading rate and environmental temperature field, offering crucial information for optimizing design parameters and guaranteeing the lifespan of the structure. Model parameters are determined for the two types of titanium alloys based on tensile creep testing results and validated through a simulation of the experimental process. In this study, a material creep model was used to predict the long-term deformation of large pressure-resistant titanium structures to ensure safe long-term operation. The safety factor used in the model is 1.5. Finite element analyses are conducted for the creep behavior of the pressure-resistant structure under real operating circumstances based on the creep constitutive model. The simulation predicts stress distribution, strain evolution, and deformation size over long periods of time by integrating complicated geometries, boundary conditions, and material characteristics. The present research can provide basic information for the local impacts of creep deformation on the inside of facilities, which helps refine design strategies to reduce possible damage risks.

Effect of Cyclic Loading Rates on Behavior of a Dissimilar-Superalloys Joint at Elevated Temperature

Effect of Cyclic Loading Rates on Behavior of a Dissimilar-Superalloys Joint at Elevated Temperature

Determination of fracture parameters for propellant/liner interface affect zone through measuring J-integral

Determination of fracture parameters for propellant/liner interface affect zone through measuring J-integral

A comparative study on mechanical-electrical-thermal characteristics and failure mechanism of LFP/NMC/LTO batteries under mechanical abuse

A comparative study on mechanical-electrical-thermal characteristics and failure mechanism of LFP/NMC/LTO batteries under mechanical abuse

Study on dynamic mechanical properties and microscopic damage mechanisms of granite after dynamic triaxial compression and thermal treatment

Study on dynamic mechanical properties and microscopic damage mechanisms of granite after dynamic triaxial compression and thermal treatment

DEM modelling of particle crushing of single carbonate sand using the improved bonded particle model

DEM modelling of particle crushing of single carbonate sand using the improved bonded particle model

Experimental and numerical study on the loading rate dependent tensile behavior of carbon fiber/epoxy interface

Experimental and numerical study on the loading rate dependent tensile behavior of carbon fiber/epoxy interface

Comparative experimental study of the effect of loading rate on the typical mechanical properties of bubble and clear ice cubes

Comparative experimental study of the effect of loading rate on the typical mechanical properties of bubble and clear ice cubes

Experimental study on the mechanical characteristics of weakly cemented mudstone under different loading rates

With the gradual shift of coal mining to the western coal mining region of China, floor heave in weakly cemented mudstone roadways has become an issue affecting the safety and efficiency of coal mine production. Additionally, different mining rates can lead to fluctuating support stresses on the roof and floor of weakly cemented mudstone roadways. Therefore, obtaining a comprehensive understanding of the mechanical properties of weakly cemented mudstone at different loading rates is conducive to improving the issue of floor heave in such roadways and provides a theoretical basis for further study. In this context, a series of uniaxial mechanical tests with concurrent acoustic emission monitoring were conducted on specimens of weakly cemented mudstone under various loading rates (0.005, 0.01, 0.05, and 0.1 mm/s). The stress‒strain and acoustic emission response curves were obtained to effectively characterize the strength, deformation, damage, macroscale instability, and crack propagation characteristics of the mudstone under the influence of loading rate effects. The research results support the following findings: (1) With increasing loading rate, the peak strength and elastic modulus of weakly cemented mudstone significantly increase, while the peak axial strain and peak radial deformation significantly decrease. (2) With increasing loading rate, the stress required to trigger the expansion of weakly cemented mudstone gradually increases, and a significant power-law relationship arises between the strain of the mudstone at the start of expansion and the loading rate. (3) With increasing loading rate, the acoustic emission ringing count of weakly cemented mudstone increases: The failure of weakly cemented mudstone changes from small-range progressive failure to sudden failure, and the failure mode transitions from shear failure to tensile‒shear composite failure. (4) The studied mudstone damage variables increase with increasing loading rate, following an approximate exponential function. The conclusions obtained in this work can provide a theoretical basis for the evolution mechanism and control of floor heave in deep roadway mining.

Study on fatigue parameters of high modulus asphalt pavement

Study on fatigue parameters of high modulus asphalt pavement

Phosphorus recovery from ultrafiltered membrane wastewater by biochar adsorption columns: The effect of loading rates

Phosphorus recovery from ultrafiltered membrane wastewater by biochar adsorption columns: The effect of loading rates

Study on the Tensile Failure Characteristics and Energy Calculation Model of Coal Seam Hard Roof Considering the Mining Speed

To reveal the influence mechanism of mining speed on roof fracture-type rockburst, the Brazilian split technique combined with acoustic emission monitoring technology was employed to study the effects of loading rates on the tensile failure characteristics and acoustic emission parameters of coal series sandstone. The linear relationship between the tensile strength of the samples and the change rate of tensile stress was determined. The mining speed was introduced into the mechanical model of initial and cyclic fracture of the hard roof, and the quantitative relationship between the maximum rate of change of tensile stress within the hard roof and the mining speed was derived. Based on this, a computational model for the bending elastic energy of the hard roof during initial and cyclic fractures, considering the mining speed, was established. The main findings are as follows: As the loading rate increases, the distribution range of acoustic emission energy in sandstone Brazilian split samples before failure widens, with a significant rise in acoustic emission ring-down counts and energy at failure. At lower loading rates, acoustic emission events primarily occur near sample failure, whereas at higher rates, they mostly happen in the early loading stage. The higher the mining speed, the less opportunity there is for internal micro-fractures to develop and expand before the hard roof fractures, which macroscopically results in increased tensile strength and a larger amount of energy released at the moment of fracture. Bending elastic energy rises approximately linearly with mining speed, and the thicker the hard roof, the more sensitive the bending elastic energy is to changes in mining speed. This effect is even more pronounced during cyclic fractures. Optimizing mining speed is crucial for preventing roof fracture-type rockbursts, especially in mining workfaces with thick and hard roofs.

Enhanced production of hydrogen-rich gas from municipal sewage sludge gasification using a CaO-RM composite catalyst

Enhanced production of hydrogen-rich gas from municipal sewage sludge gasification using a CaO-RM composite catalyst

Bonding behaviour between steel fibre and concrete matrix after experiencing elevated temperature at various loading rates

Abstract The bonding behaviour between steel fibre and concrete matrix at elevated temperature and various loading rates was investigated. Pullout tests were carried out on the hooked-end steel fibre reinforced concrete specimen and the effects of elevated temperatures (200, 400, and 600°C) and loading rates (2, 10, and 50 mm·min−1) were considered. The ultimate bond strength and energy absorption were discussed to evaluate the bonding behaviour. The results revealed that the bonding behaviour for the case of 400°C performed best, while the bonding behaviour for the case of 600°C performed the worst. At room temperature, the bonding behaviour is similar to the case of 200°C. In addition, the higher the loading rate, the greater the fluctuation of the bond slip curve of the specimen, and higher ultimate pullout load and energy absorption may be observed.

Multiscale finite element modeling of origami-inspired dual matrix deployable composite with visco-hyperelastic hinge

Multiscale finite element modeling of origami-inspired dual matrix deployable composite with visco-hyperelastic hinge

A rate-dependent cohesive zone model for dynamic crack growth in carbon nanotube reinforced polymers

A rate-dependent cohesive zone model for dynamic crack growth in carbon nanotube reinforced polymers

Effect of loading rate on energy and acoustic emission characteristics of tensile fracture and shear fracture for red sandstone

Effect of loading rate on energy and acoustic emission characteristics of tensile fracture and shear fracture for red sandstone