scholarly journals Experimental and numerical study of drill bit drop tests on Kuru granite

2017 ◽  
Vol 375 (2085) ◽  
pp. 20160176 ◽  
Author(s):  
Marion Fourmeau ◽  
Alexandre Kane ◽  
Mikko Hokka
Keyword(s):  
Impact Energy ◽  
Numerical Study ◽  
Experimental Testing ◽  
Drop Test ◽  
Surface Shape ◽  
Test Machine ◽  
Drill Bit ◽  
Rock Interaction ◽  
Drop Tests ◽  
The Impact

This paper presents an experimental and numerical study of Kuru grey granite impacted with a seven-buttons drill bit mounted on an instrumented drop test machine. The force versus displacement curves during the impact, so-called bit–rock interaction (BRI) curves, were obtained using strain gauge measurements for two levels of impact energy. Moreover, the volume of removed rock after each drop test was evaluated by stereo-lithography (three-dimensional surface reconstruction). A modified version of the Holmquist–Johnson–Cook (MHJC) material model was calibrated using Kuru granite test results available from the literature. Numerical simulations of the single drop tests were carried out using the MHJC model available in the LS-DYNA explicit finite-element solver. The influence of the impact energy and additional confining pressure on the BRI curves and the volume of the removed rock is discussed. In addition, the influence of the rock surface shape before impact was evaluated using two different mesh geometries: a flat surface and a hyperbolic surface. The experimental and numerical results are compared and discussed in terms of drilling efficiency through the mechanical specific energy. This article is part of the themed issue ‘Experimental testing and modelling of brittle materials at high strain rates’.

Dynamic Energy Absorption Performances of Rain Forest Vehicle (RFV) under Frontal Impact

2014 ◽  
Vol 67 (3) ◽  
Author(s):  
M. S. Othman ◽  
Z. Ahmad
Keyword(s):  
Energy Absorption ◽  
Impact Energy ◽  
Impact Loading ◽  
Rain Forest ◽  
Experimental Testing ◽  
Rigid Wall ◽  
Crash Analysis ◽  
Frontal Impact ◽  
Frontal Section ◽  
The Impact

This paper treats the crash analysis and energy absorption response of Rain Forest Vehicle (RFV) subjected to frontal impact scenario namely impacting rigid wall and column. Dynamic computer simulation techniques validated by experimental testing are used to carry out a crash analysis of such vehicle. The study aims at quantifying the energy absorption capability of frontal section of RFV under impact loading, for variations in the load transfer paths and geometry of the crashworthy components. It is evident that the proposed design of the RFV frontal section are desirable as primary impact energy mitigation due to its ability to withstand and absorb impact loads effectively. Furthermore, it is found that the impact energy transmitted to the survival room may feasibly be minimized in these two impact events. The primary outcome of this study is design recommendation for enhancing the level of safety of the off-road vehicle where impact loading is expected.   

Dynamic Energy Absorption Performances of Rain Forest Vehicle (RFV) under Frontal Impact

2014 ◽  
Vol 69 (3) ◽  
Author(s):  
M. S. Othman ◽  
Z. Ahmad
Keyword(s):  
Energy Absorption ◽  
Impact Energy ◽  
Impact Loading ◽  
Rain Forest ◽  
Experimental Testing ◽  
Rigid Wall ◽  
Crash Analysis ◽  
Frontal Impact ◽  
Frontal Section ◽  
The Impact

This paper treats the crash analysis and energy absorption response of Rain Forest Vehicle (RFV) subjected to frontal impact scenario namely impacting rigid wall and column. Dynamic computer simulation techniques validated by experimental testing are used to carry out a crash analysis of such vehicle. The study aims at quantifying the energy absorption capability of frontal section of RFV under impact loading, for variations in the load transfer paths and geometry of the crashworthy components. It is evident that the proposed design of the RFV frontal section are desirable as primary impact energy mitigation due to its ability to withstand and absorb impact loads effectively. Furthermore, it is found that the impact energy transmitted to the survival room may feasibly be minimized in these two impact events. The primary outcome of this study is design recommendation for enhancing the level of safety of the off-road vehicle where impact loading is expected.   

Effect of specimen size and ball size on breakage throughput in the drop-weight test

2018 ◽  
Vol 233 (2) ◽  
pp. 202-210 ◽  
Author(s):  
Mehdi Akhondizadeh ◽  
Masoud Rezaeizadeh
Keyword(s):  
Impact Energy ◽  
Specimen Size ◽  
Test Machine ◽  
Ball Size ◽  
Drop Weight ◽  
Weight Test ◽  
Drop Weight Test ◽  
Steel Balls ◽  
The Impact ◽  
Specific Impact

Effects of specimen size and ball size on the breakage throughput under the impact loading are investigated using a drop-weight test machine. Samples are square-shaped building stones ranging 20–60 mm in width and 22–256 g in mass. They include granite, marble, and two types of travertine with the thickness of 15 mm. The impact energies, up to 160 J, are achieved by falling balls in a drop-weight test machine. Several steel balls with the diameter of 60, 84, 96, and 120 mm have been used as an impactor. The ball size is a parameter whose effect on the breakage throughput is investigated here. Results show that the larger specimens have better breakage than the smaller ones at the same specific impact energy. It is also indicated that, at constant specific impact energy, the smaller balls behave more efficiently than the larger balls.

scholarly journals Research on Impact Stress Transfer Characteristics of Lunar Rock Coring Drill

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Peng Li ◽  
Yizhuo Wang ◽  
Bo Xu ◽  
Junwei Liu ◽  
Weiwei Zhang
Keyword(s):  
Impact Energy ◽  
Lunar Surface ◽  
Cutting Edge ◽  
Design Parameters ◽  
Drill Bit ◽  
Drilling Tool ◽  
Drill Stem ◽  
Impact Stress ◽  
Transfer Characteristics ◽  
The Impact

In the whole lunar surface drilling and sampling task, it is critical to make the operation of the drilling and sampling impact system efficient and reliable. This paper focuses on how to improve the impact stress obtained at the cutting edge of the drill bit. Firstly, with the objective of maximizing the output impact energy, the design parameters of the percussive mechanism are optimally selected; based on the one-dimensional stress wave transfer theory, the collision input model and transfer models of impact stress in the drilling tool are established. Secondly, in order to verify the above design parameters and theoretical models, the percussive drive characteristics’ test and the transfer characteristics’ tests of impact stress in the drill stem and drilling tool joints are carried out in turn. The experimental results are consistent with the theoretical analysis, which clarifies the transfer characteristics of the impact stress at the various stages of generation, incidence, and transfer to the cutting edge. It was finally found that increasing the percussive frequency and impact energy of the percussive mechanism as well as the contact stiffness of the collision surface can increase the incident impact stress of the drilling tool, while reducing the length of the screw connection between the drill bit and the drill stem can reduce the impact stress loss. This provides a theoretical reference for the design of the percussive mechanism and drilling tools in lunar surface drilling and sampling tasks.

Hybrid Simulation Method for PWB Level Drop Tests

2005 ◽  
Author(s):  
Jiansen Zhu ◽  
Esa Hussa ◽  
Juscelino Okura ◽  
Santosh Shetty
Keyword(s):  
Large Deformation ◽  
Simulation Method ◽  
Standard Test ◽  
Test Method ◽  
Drop Test ◽  
Nonlinear Material ◽  
Time Curve ◽  
Impulse Duration ◽  
Drop Tests ◽  
The Impact

PWB level drop tests are widely used as a standard test method to evaluate the reliability of PWB and packages under drop conditions (JEDEC Standard JESD22-B104-A). The drop height and test setup need be adjusted in order to achieve the requirements of a peak shock of 1500g and an impulse duration of 0.5 ms. Generally, the ground need be covered with a thin layer of rubber pad to absorb some of the impact energy. However, this rubber pad will bring challenges for modelling due to large deformation, nonlinear hyperelasticity, and contact. And sometimes, it may also cause the convergence problem. Therefore, a hybrid drop simulation method was developed. This hybrid method can not only circumvent the difficulties mentioned, but also increase the efficiency and reduce the CPU time of PWB drop simulation. When simulating a PWB board level drop test, generally, not only the PWB and the components assembled on it need be modelled, but also the drop vehicle, rubber pad, and ground should be included in the model. For the hybrid drop simulation, however, only part of drop vehicle need be modeled and there is no need to model the ground and the contact between the ground and the drop vehicle. Then an acceleration time curve measured from drop test is applied to the hybrid model so that the responses of the model will mimic the real drop situation. In this way, not only the simulation time is reduced due to smaller model sizes, but also can some difficulties related to large deformation, contact, and nonlinear material properties be avoided. Finally, a comparison of a bare PWB and a populated PWB drop cases was used to validate this hybrid drop simulation method. A reasonable correlation was achieved.

scholarly journals The effects of gravel cushion particle size and thickness on the coefficient of restitution in rockfall impacts

2018 ◽  
Vol 18 (6) ◽  
pp. 1811-1823 ◽  
Author(s):  
Chun Zhu ◽  
Dongsheng Wang ◽  
Xing Xia ◽  
Zhigang Tao ◽  
Manchao He ◽  
...  
Keyword(s):  
Particle Size ◽  
Impact Energy ◽  
Coefficient Of Restitution ◽  
Open Pit ◽  
Test Results ◽  
Drop Tests ◽  
Damage Depth ◽  
The Stability ◽  
Energy Absorbing ◽  
The Impact

Abstract. Gravel cushions are widely used to absorb the impact energy of falling rocks in open-pit mines. A particularly important application is to enhance the energy-absorbing capacity of rockfall sheds. In this paper, we study how varying the thickness and particle size of a gravel cushion influences its energy-consumption and buffering effects. We performed a series of laboratory drop tests by dropping blocks from a fixed height onto cushions of different thicknesses and particle sizes. The results indicate that, for a given impact energy, the cushion thickness has a strong influence on the measured coefficient of restitution (COR) and therefore impact pressure. Additional tests were performed to study how the radius of the block and the height it is dropped from affect the measured COR. This showed that as the movement height of the block is increased the COR also increases, and blocks with larger radii exhibit a larger variability in measured COR. Finally, we investigated the influence of rockfall block radius, r, movement height, H, cushion thickness, h, and particle size, d, on the COR and the damage depth, L, of the cushion. The test results reveal that the cushion thickness is the primary design parameter, controlling not only COR, but also the stability of the cushion material. The results provide a theoretical and practical basis for the design of gravel cushions for rockfall protection.

Comparative Study of Motorcycle Helmets Impact Performance

2014 ◽  
Vol 575 ◽  
pp. 306-310
Author(s):  
Hamzah Azhar ◽  
Aqbal Hafeez Ariffin ◽  
Solah Mohd Syazwan ◽  
Mohd Hafzi Md Isa ◽  
Yahaya Ahmad ◽  
...  
Keyword(s):  
Comparative Study ◽  
Impact Energy ◽  
Drop Test ◽  
Test Machine ◽  
Impact Speed ◽  
Impact Performance ◽  
Energy Absorbing ◽  
Motorcycle Helmets ◽  
Service Duration

Two sets of new and in-service helmets were impact tested using a drop test machine, in accordance to established helmet test protocols. The first test for full helmets was executed in compliance with standard speed requirements of 5.9 m/s in which three of five new helmets performed poorly. The second set utilized lower impact speed of 4 m/s for individual helmet components test. New helmet liners absorbed 5 times more impact energy than the in-service liners while the new shell was 19.3% better in dispersing impact energy than the in-service shell. The undesirable changes in liner thickness have explicit effect on the liner density which is translated into reduction in energy absorbing potential. In brief, exposure to weathering stresses and use intensities has affected helmet impact performance, regardless of service duration.

Mechanical and Thermal Assessment by BAM of a New Package Design for the Transport of SNF From a German Research Reactor

2020 ◽  
Author(s):  
Steffen Komann ◽  
Viktor Ballheimer ◽  
Thomas Quercetti ◽  
Robert Scheidemann ◽  
Frank Wille
Keyword(s):  
Research Reactor ◽  
Drop Test ◽  
Radioactive Material ◽  
Test Facility ◽  
Test Sequence ◽  
Thermal Safety ◽  
Package Design ◽  
Drop Tests ◽  
Approval Procedure ◽  
The Impact

Abstract For disposal of the research reactor of the Technical University Munich FRM II a new transport and storage cask design was under approval assessment by the German authorities on the basis of International Atomic Energy Agency (IAEA) requirements. The cask body is made of ductile cast iron and closed by two bolted lid systems with metal seals. The material of the lids is stainless steel. On each end of the cask the wood-filled impact limiters are installed to reduce impact loads to the cask under drop test conditions. In the cavity of the cask a basket for five spent fuel elements is arranged. This design has been assessed by the Bundesanstalt für Materialforschung und -prüfung (BAM) in view to the mechanical and thermal safety analyses, the activity release approaches, and subjects of quality assurance and surveillance for manufacturing and operation of the package. For the mechanical safety analyses of the package a combination of experimental testing and analytical/numerical calculations were applied. In total, four drop tests were carried out at the BAM large drop test facility. Two tests were carried out as a full IAEA drop test sequence consisting of a 9m drop test onto an unyielding target and a 1m puncture bar drop test. The other two drop tests were performed as single 9m drop tests and completed by additional analyses for considering the effects of an IAEA drop test sequence. The main objectives of the drop tests were the investigation of the integrity of the package and its safety against release of radioactive material as well as the test of the fastening system of the impact limiters. Furthermore, the acceleration and strain signals measured during the tests were used for the verification of finite-element (FE) models applied in the safety analysis of the package design. The FE models include the cask body, the lid system, the inventory and the impact limiters with the fastening system. In this context special attention was paid to the modeling of the encapsulated wood-filled impact limiters. Additional calculations by using the verified numerical model were done to investigate e.g. the brittle fracture of the cask body made of ductile cask iron within the package design approval procedure. The thermal safety assessment was based on analytical energy balance calculations and FE analyses. As an additional point of evaluation in frame of approval procedure, the effect of possible impact limiter burning under accident conditions of transport was considered by the applicant and assessed by BAM. This paper describes the package design assessment from the point of view of the competent authority BAM including the applied assessment strategy, the conducted drop tests and the additional calculations by using numerical and analytical methods.

Experimental Research on the Low Velocity Impact Damage of CCF300/QY8911 Composite Laminates

2012 ◽  
Vol 583 ◽  
pp. 179-182
Author(s):  
Hai Ming Hong ◽  
Ming Li ◽  
Jian Yu Zhang ◽  
Yi Ning Zhang
Keyword(s):  
Impact Energy ◽  
Composite Laminates ◽  
Low Velocity Impact ◽  
Test Machine ◽  
Low Velocity ◽  
Velocity Impact ◽  
Damage Pattern ◽  
The Impact ◽  
Dent Depth ◽  
Delamination Damage

A group of low-velocity impact tests on CCF300/QY8911 composite laminates were implemented by the low-velocity drop hammer test machine. The dent depth and the internal damage pattern with corresponding impact energy were studied, the internal delamination damage state of laminates after impact were observed through thermal layer exposing tests, and the mechanism of low-velocity impact delamination damage were discussed. The results indicated that there existed a significant inflection point in the curve of impact energy verse dent depth of CCF300/QY8911 composite material, which was also the transition point of different damage patterns. When the impact energy was smaller than the inflection energy, the damage pattern consisted mainly of matrix flaws and delamination damages, but when the impact exceeded the inflection energy, delamination damage hardly expanded while the expansion of damage was mainly fiber break.

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