scholarly journals Analysis of load of a powered roof support’s hydraulic leg

2018 ◽  
Vol 71 ◽  
pp. 00002 ◽  
Author(s):  
Dawid Szurgacz ◽  
Jarosław Brodny
Keyword(s):  
Rock Mass ◽  
Hydraulic System ◽  
Impact Load ◽  
Load Condition ◽  
Dynamic Impact ◽  
Registration System ◽  
Free Falling ◽  
The Impact ◽  
Impact Mass ◽  
Roof Support

The main purpose of the powered roof support is to protect headings from the impact of the rock mass. The result of such impact is static and dynamic load impacting the support section, which is carried by its construction. The basic elements of the construction of the support are hydraulic legs, whose task is to ensure adequate strength of its setting. Particularly in the case of dynamic impact of the rock mass, these legs are exposed to a very unfavourable load condition. Therefore, it is necessary to conduct tests to determine the parameters of operation for this type of loads. The paper presents the results of tests on the hydraulic leg subjected to impact load with free falling impact mass. The purpose of the research was to determine the parameters of the leg's operation, i.e. the time periods of pressure in the space under the piston and other elements of the hydraulic system. The tests were conducted in compliance with designed methodology and included innovative registration system. The obtained results clearly indicate the correctness of the adopted assumptions. According to the authors, the results should be applied during selection and operation of a powered roof support.

scholarly journals Analysis of rock mass dynamic impact influence on the operation of a powered roof support control system

2018 ◽  
Vol 29 ◽  
pp. 00006 ◽  
Author(s):  
Dawid Szurgacz ◽  
Jaroław Brodny
Keyword(s):  
Rock Mass ◽  
Real Life ◽  
High Energy ◽  
Hard Coal ◽  
Underground Excavation ◽  
Dynamic Impact ◽  
Support Unit ◽  
Geological Conditions ◽  
Innovative Solutions ◽  
Roof Support

A powered roof support is a machine responsible for protection of an underground excavation against deformation generated by rock mass. In the case of dynamic impact of rock mass, the proper level of protection is hard to achieve. Therefore, the units of the roof support and its components are subject to detailed tests aimed at acquiring greater reliability, efficiency and efficacy. In the course of such test, however, it is not always possible to foresee values of load that may occur in actual conditions. The article presents a case of a dynamic load impacting the powered roof support during a high-energy tremor in an underground hard coal mine. The authors discuss the method for selecting powered roof support units proper for specific forecasted load conditions. The method takes into account the construction of the support and mining and geological conditions of an excavation. Moreover, the paper includes tests carried out on hydraulic legs and yield valves which were responsible for additional yielding of the support. Real loads impacting the support unit during tremors are analysed. The results indicated that the real registered values of the load were significantly greater than the forecasted values. The analysis results of roof support operation during dynamic impact generated by the rock mass (real life conditions) prompted the authors to develop a set of recommendations for manufacturers and users of powered roof supports. These include, inter alia, the need for innovative solutions for testing hydraulic section systems.

Quasi-Static Lap Shear and Dynamic Impact of High Performance VHB™ Acrylic Foam and Adhesive Transfer Tape Bonded Aluminum Joints Subjected to Environmental Degradation

2005 ◽  
Author(s):  
Manoj Anakapalli ◽  
P. Raju Mantena ◽  
Ahmed Al-Ostaz ◽  
S. Jimmy Hwang
Keyword(s):  
High Performance ◽  
Shear Failure ◽  
Electrochemical Impedance ◽  
Impact Load ◽  
Bond Quality ◽  
Dynamic Impact ◽  
Impulse Frequency ◽  
Lap Shear ◽  
Failure Loads ◽  
The Impact

A range of 3M™ VHB™ acrylic foam tapes and high performance adhesive transfer tapes were used to bond 1” × 1/8″ (25.4 mm × 3.175 mm) aluminum 2024 T-4 adherends in single-lap joint (SLJ) and three-point end-notched flexure (ENF) configurations. Three types of 0.045” thick double-coated acrylic foam tapes: Foam 41, 50 and 52 (firm, soft and softer), and three types of adhesive transfer tapes: Adhesives 69, 73 and 85 (0.005”, 0.01” and 0.005” thick, respectively) were used for this study. The samples were subjected to two types of aggressive environments simulating extreme service conditions: freeze-thaw cycling from 10°F to 50°F at 6 cycles per day (ASTM C666 Procedure A) for 21 days with samples immersed in water; heat-cool cycling (with 90% of maximum recommended temperature by the manufacturer of both acrylic foam and adhesive transfer tapes attained at 70% relative humidity) and 3 cycles per day for 21 days. Initially the impulse-frequency response vibration and electrochemical impedance spectroscopy (EIS) techniques were used for monitoring bond quality nondestructively and selecting the best out of 250 fabricated samples. After obtaining baseline data, the specimens were subjected to quasi-static lap-shear and dynamic impact loading to compare their lap-shear failure loads and shear energy along with the impact load and energy absorbed.

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

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.

scholarly journals Flexible-Rigid Wheelset Introduced Dynamic Effects due to Wheel Tread Flat

2021 ◽  
Vol 2021 ◽  
pp. 1-21
Author(s):  
Awel Momhur ◽  
Y. X. Zhao ◽  
Liwen Quan ◽  
Sun Yazhou ◽  
Xialong Zou
Keyword(s):  
High Speed ◽  
Statistical Approach ◽  
Impact Load ◽  
Vertical Acceleration ◽  
Vehicle Speed ◽  
Dynamic Impact ◽  
Element Analysis ◽  
Wheel Flat ◽  
Wheel Radius ◽  
The Impact

The widespread faults that occur in railway wheels and can cause a massive dynamic impact are the wheel tread flat. The current work considered changes in vehicle speed or wheel radius deviation and studied the dynamic impact load. The modal technique for the impact evaluation induced by the wheel flat was proposed via the finite element analysis (FEA) software package ANSYS, integrated into a multibody dynamics model of the high-speed train CRH2A (EMU) through SIMPACK. The irregularity track line has developed and depends on the selected simulation data points. Additionally, a statistical approach is designed to analyze the dynamic impact load response and effect and consider different wheel flat lengths and vehicle speeds. The train speed influence on the flat size of the vertical wheel-rail impact response and the statistical approach are discussed based on flexible, rigid wheelsets. The results show that the rigid wheel flat has the highest vertical wheel impact load and is more significant than the flexible wheel flat force. The consequences suggest that the wheelset flexibility can significantly improve vertical acceleration comparably to the rigid wheel flats. In addition, the rendering of the statistical approach shows that the hazard rate, PDF, and CDF influence increase when the flat wheel length increases.

scholarly journals DYNAMIC IMPACT WEAR AND IMPACT RESISTANCE OF W-B-C COATINGS

2020 ◽  
Vol 27 ◽  
pp. 37-41
Author(s):  
Josef Daniel ◽  
Jan Grossman ◽  
Vilma Buršíková ◽  
Lukáš Zábranský ◽  
Pavel Souček ◽  
...  
Keyword(s):  
Impact Test ◽  
Impact Load ◽  
Protective Coatings ◽  
Impact Resistance ◽  
Impact Testing ◽  
The Novel ◽  
Test Results ◽  
Dynamic Impact ◽  
Impact Deformation ◽  
The Impact

Coated components used in industry are often exposed to repetitive dynamic impact load. The dynamic impact test is a suitable method for the study of thin protective coatings under such conditions. Aim of this paper is to describe the method of dynamic impact testing and the novel concepts of evaluation of the impact test results, such as the impact resistance and the impact deformation rate. All of the presented results were obtained by testing two W-B-C coatings with different C/W ratio. Different impact test results are discussed with respect to the coatings microstructure, the chemical and phase composition, and the mechanical properties. It is shown that coating adhesion to the HSS substrate played a crucial role in the coatings’ impact lifetime.

scholarly journals Dynamic Analysis for the Hydraulic Leg Power of a Powered Roof Support

Energies ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5715
Author(s):  
Dawid Szurgacz
Keyword(s):  
Rock Mass ◽  
Theoretical Analysis ◽  
Dynamic Analysis ◽  
Experimental Studies ◽  
Geological Structure ◽  
Basic Element ◽  
Bench Test ◽  
Dynamic Power ◽  
The Impact ◽  
Roof Support

This paper presents the results of a study conducted to determine the dynamic power of a hydraulic leg. The hydraulic leg is the basic element that maintains the position of a powered roof support. It is located in the structure between the canopy and the floor base. The analysis assumes that its power must be greater than the energy of the impact of the rock mass. The energy of the rock mass is generated by tremors caused mainly by mining exploitation. The mining and geological structure of the rocks surrounding the longwall complex also have an influence on this energy generation. For this purpose, stationary tests of the powered roof support were carried out. The analysis refers to the space under the piston of the leg, which is filled with fluid at a given pressure. The bench test involved spreading the leg in the test station under a specified pressure. It was assumed that the acquisition of dynamic power would be at the point of pressure and increase in the space under the piston of the leg under forced loading. Based on the experimental studies carried out, an assessment was made with the assumptions of the methodology adopted. The results of the theoretical analysis showed consistency with the experimental results.

Based on 3D Virtual Prototype Technology and Finite Element Analysis of the Optimization of the Automobile Front Axle

2014 ◽  
Vol 684 ◽  
pp. 330-334
Author(s):  
Heng Yi Yuan ◽  
Ming Wang He
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Modal Analysis ◽  
Impact Load ◽  
Load Condition ◽  
Front Axle ◽  
Mode Shapes ◽  
Element Analysis ◽  
Emergency Braking ◽  
The Impact

The front axle is an important part of a car, directly affects the dynamic characteristics of car. Based on UG NX6.0 for automobile front axle parts 3D modeling, finite element analysis software ANSYS modal analysis was carried out on the front axle, and extract their first four order natural frequency and vibration mode shapes, the automobile front axle structure stress analysis and stress distribution nephogram of get parts. Analysis of the impact load condition and emergency braking conditions modal analysis, and further to fatigue analysis of the front axle bridge shell, for provide valuable reference data for the reasonable design of parts. For the kinetics of further research and improvement of front axle provides the theoretical basis, but also provides reference to the actual test.

scholarly journals Dynamic Tests of a Leg in a Powered Roof Support Equipped with an Innovative Hydraulic System

2018 ◽  
Vol 41 ◽  
pp. 03019 ◽  
Author(s):  
Dawid Szurgacz ◽  
Jarosław Brodny
Keyword(s):  
Control System ◽  
Dynamic Load ◽  
Hydraulic System ◽  
Free Fall ◽  
Dynamic Loads ◽  
Hydraulic Control ◽  
Powered Support ◽  
Static And Dynamic Loads ◽  
The Impact ◽  
Roof Support

Static and dynamic loads impact on a powered roof support during its operation. The dynamic loads lead to a number of consequences for the construction and the entire hydraulic system. With the increase of depth and intensity of exploitation, the number of events during which the dynamic load is greater increases. Therefore, it is necessary to research the whole unit of the support and its components under the impact of dynamic load. The article presents the results of tests of a hydraulic leg designed to work in the powered support and dynamically loaded with free fall drop. An innovative hydraulic system type DOH was mounted in the subject leg. As a result of the conducted tests, the dynamic parameters of the tested system were determined. The aim of the research was also to determine the impact of drop’s energy on the operating parameters of the tested system. The tested hydraulic system is a part of an innovative electro hydraulic control system of the powered roof support. The Authors believe that the obtained results will allow to create opportunities for the practical application of the tested system and the entire wireless control system of the mining roof support.

Design of the Roof Support with Strait-Line Mechanism

2014 ◽  
Vol 1036 ◽  
pp. 553-558 ◽  
Author(s):  
Aleksander Gwiazda
Keyword(s):  
Rock Mass ◽  
Hydraulic System ◽  
Mining Industry ◽  
Main Idea ◽  
Vertical Position ◽  
Mining Equipment ◽  
Design Work ◽  
Deep Mine ◽  
Mechanical Devices ◽  
Roof Support

One of the most important aspects of machine designing is to balance between the economic requirements and the safety ones. Taking into account these requirements it was conducted the design work to elaborate the new concept of the mining roof support that fulfil them. The mining roof support is a mining equipment that has the most influence on the safety of work in deep coal mines and on the productivity of deep mines. Moreover the hydraulic roof support generally accounts for over 50% of the total value of a coal mining and excavating system. It is consider not only with the complexity of the roof support but also with the accepted direction of the development of mining supports. Generally designers elaborate heavier constructions with prof of larger diameters and loads. In this way the support system must be prepare not only to withdraw the rock mass forces but also the forces generated by its hydraulic system. These prerequisites underlie the new project of a roof support. This project bases also on many Polish patents concerning the mechanical devices and hydraulic equipment of a mining roof support. The main idea of the work was to elaborate the scheme of a support that will be compatible with the system of loads generating by the rock mass and by the conditions of work in a deep mine. As a result it was proposed the concept of a hydraulic roof support equipped with four props that work only in a vertical position. To realize that task it was proposed the special designed strait-line mechanism protected by Polish patent. This mechanism is supported by gas springs with low resistance. These springs help to eliminate horizontal forces loaded the construction. It has been also designed special flexible roof part (also patented) that allows to eliminate the horizontal component of roof rock loads. The hydraulic system is equipped with gas dampers that compensate dynamic loads during bumps in longwalls. The design of the dampers is also patented. In the result of design process the new concept of the roof support have been elaborated. One prototype has been manufactured. According to analysis it is about half the weight of standard roof support and the cost of it reaches the 50% of a standard support. It should be the optimal proposal for the European mining industry.

Sign in / Sign up

Export Citation Format

Share Document