Comparative Shear Tests of Bolt Rods Under Static and Dynamic Loading

AbstractThis article presents the methodology and results of single shear tests of bolt rods under dynamic impact loading generated by means of a drop hammer. Comparative analysis was also performed for bolt rod load capacity, stress and shear work under static and dynamic (impact) loading. The developed method of single shear testing of bolt rods under impact loading makes it possible to obtain repeatable test results concerning maximum bolt rod shearing force, shear stress and shear work values.Comparative shear tests of four types of bolt rods under static and impact loading showed that the APB-type bolt rods made of AP770 steel, which was characterised by having the highest strength, exhibited the greatest shear work. AM22-type bolt rods exhibited a very similar work value. Though the AM22-type bolt rods made of A500sh steel demonstrated lower strength than the APB-type bolts, as well as a smaller diameter and cross section, they dissipated the impact energy better thanks to their higher plasticity. This could indicate the direction of optimisation for bolt rods in order to increase their impact strength.Mathematical relationships were also formulated for selected tests, describing the real single shear courses F d =f(t) of bolts under impact loading. The obtained relationships could be applied in the load assessment process of bolt rods intended for use under roof caving, tremor and rock burst conditions.

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3D Physical Modelling Study of Shield-Strata Interaction under Roof Dynamic Loading Condition

Shock and Vibration ◽

10.1155/2021/6618954 ◽

2021 ◽

Vol 2021 ◽

pp. 1-7

Author(s):

Shengli Yang ◽

Hao Yue ◽

Gaofeng Song ◽

Junjie Wang ◽

Yanyao Ma ◽

...

Keyword(s):

Impact Loading ◽

Loading Condition ◽

Impact Load ◽

Physical Modelling ◽

Coal Face ◽

Dynamic Impact ◽

Immediate Roof ◽

Cutting Height ◽

The Impact ◽

Dynamic Impact Loading

The dynamic hazards in the open face area caused by the impact load of the massive strong roof become increasingly severe with the increase in the cutting height of the longwall face and its depth of cover. Understanding the strata-shield interaction under the dynamic impact loading condition may relieve the dynamic hazards. In this paper, a 3D physical modelling platform is developed to study the interaction between the roof strata and the longwall shield under the dynamic impact load conditions. A steel plate is dropped to the coal face wall at a certain height above the immediate roof to simulate the free fall of the main roof and the dynamic impact loading environment. The occurrence of major roof falls is modelled at different height above the model and at different positions relative to the longwall faceline. The large-cutting-height and top-coal-caving mining methods are modelled in the study to include the nature of the immediate roof. The results show that the level of face and roof failures depends on the magnitude of the dynamic impact load. The position and height of the roof fall have an important influence to the stability of the roof and face. The pressures on the shield and the solid coal face are relieved for the top-coal-caving face as compared to the large-cutting-height face.

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Energy Absorbing Properties Analysis of Layers Structure of Titanium Alloy Ti6Al4V during Dynamic Impact Loading Tests

Materials ◽

10.3390/ma14237209 ◽

2021 ◽

Vol 14 (23) ◽

pp. 7209

Author(s):

Dominik Głowacki ◽

Wojciech Moćko ◽

Michał Marczak ◽

Anna Głowacka ◽

Cezary Kraśkiewicz

Keyword(s):

Plastic Deformation ◽

Titanium Alloy ◽

Impact Loading ◽

Equivalent Plastic Strain ◽

Stress Triaxiality ◽

Absorbed Energy ◽

Dynamic Impact ◽

Titanium Alloy Ti6al4v ◽

The Impact ◽

Dynamic Impact Loading

This paper presents the testing methodology of specimens made of layers of titanium alloy Ti6Al4V in dynamic impact loading conditions. Tests were carried out using a drop-weight impact tower. The test methodology allowed us to record parameters as displacement or force. Based on recorded data, force and absorbed energy curves during plastic deformation and sheet perforation were created. The characteristics of the fractures were also analyzed. The impact test simulation was carried out in the ABAQUS/Explicit environment. Results for one, two, and three layers of titanium alloy were compared. The increase in force required to initialize the damage and the absorbed energy during plastic deformation can be observed with an increase in the number of layers. The increase in absorbed energy is close to linear. In the simulation process, parameters such as Huber–Mises–Hencky stress value, equivalent plastic strain, temperature increase, and stress triaxiality were analyzed.

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Testing Study on Damage Fracture Responses of Rock under Dynamic Impact Loading

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.255-260.1815 ◽

2011 ◽

Vol 255-260 ◽

pp. 1815-1819 ◽

Cited By ~ 1

Author(s):

Ping Cao ◽

Yi Xian Wang ◽

Kai Wen Xia

Keyword(s):

Crack Length ◽

Impact Velocity ◽

Impact Loading ◽

Test Results ◽

Dynamic Impact ◽

Destructive Effect ◽

Propagation Length ◽

Break Area ◽

The Impact ◽

Dynamic Impact Loading

The dynamic impact loading has the destructive effect to the surrounding rock mass. Rock specimen such as rock plate was found to become invalid under dynamic impact loading. This paper presents brittle damage evolution law for dynamic impact damage of brittle rock based on low velocity (10m/s~40m/s) impact test, when a source of impact loading is applied to a rock plate specimen, damage cracks are developed from the source to the boundaries. This paper is concerned with the description and explanation of this phenomenon. The test results show that the cracks propagation length and break area are not arbitrary, but are influenced by the angle of dynamic impact loading. According to the test results, the study found that the scope of impact resistance optimization angle is about 30°~45°, and the cuspidal point of impact velocity is about 30m/s~35m/s; The crack length and the break area increase with the increase of the impact loading; When the break area decreases abruptly, the crack length increases suddenly, which shows that there was an obvious incubation period of crack forming, at first some pits appearing on the verge of the rock plate and the propagation rate of crack length and break area decreasing with the impact velocity increasing.

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Failure characteristics of the isolated distal radius in response to dynamic impact loading

Journal of Orthopaedic Research® ◽

10.1002/jor.22009 ◽

2011 ◽

Vol 30 (6) ◽

pp. 885-892 ◽

Cited By ~ 6

Author(s):

Timothy A. Burkhart ◽

David M. Andrews ◽

Cynthia E. Dunning

Keyword(s):

Distal Radius ◽

Impact Loading ◽

Dynamic Impact ◽

Failure Characteristics ◽

Dynamic Impact Loading

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Crushing Susceptibility of Vetch Seeds Under Impact Loading

Cercetari Agronomice in Moldova ◽

10.1515/cerce-2017-0031 ◽

2017 ◽

Vol 50 (4) ◽

pp. 5-16

Author(s):

F. Shahbazi

Keyword(s):

Moisture Content ◽

Impact Energy ◽

Impact Loading ◽

Impact Damage ◽

Mechanical Damage ◽

Seed Moisture Content ◽

Mean Values ◽

Seed Moisture ◽

Mathematical Relationships ◽

The Impact

AbstractMechanical damage of seeds due to harvest, handling and other process is an important factor that affects the quality and quaintly of seeds. The objective of this research was to determine the effects of moisture content and the impact energy on the breakage susceptibility of vetch seeds. The experiments were conducted at moisture contents of 7.57 to 25% (wet basis) and at the impact energies of 0.1, 0.2 and 0.3 J, using an impact damage assessment device. The results showed that impact energy, moisture content, and the interaction effects of these two variables significantly influenced the percentage breakage in vetch seeds (p<0.01). Increasing the impact energy from 0.1 to 0.3 J caused a significant increase in the mean values of seeds breakage from 41.69 to 78.67%. It was found that the relation between vetch seeds moisture content and seeds breakage was non-linear, and the extent of damaged seeds decreased significantlyas a polynomial (from 92.47 to 33.56%) with increasing moisture (from 7.57 to 17.5%) and reached a minimum at moisture level of about 17.5%. Further increase in seed moisture, however, caused an increase in the amount of seeds breakage. Mathematical relationships composed of seed moisture content and impact energy, were developed for accurately description the percentage breakage of vetch seeds under impact loading. It was found that the models have provided satisfactory results over the whole set of values for the dependent variable.

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