scholarly journals Influence of Incremental Impact on the Damage of Coal-Rock under Unidirectional Constraint

2019 ◽  
Vol 2019 ◽  
pp. 1-9
Author(s):  
Hongbao Zhao ◽  
Huan Zhang ◽  
Jinyu Li ◽  
Nansong Ju ◽  
Zhijie Wen
Keyword(s):  
Impact Load ◽  
Damage Model ◽  
Impact Resistance ◽  
Cumulative Damage ◽  
Axial Pressure ◽  
Loading Test ◽  
Damage Degree ◽  
Coal Rock ◽  
The Impact ◽  
Pendulum Impact

Taking the briquette sample as research object, the influence of the incremental impulse (momentum) on the damage of coal-rock under different uniaxial axial pressure was studied by using the self-developed pendulum impact dynamic loading test device, cooperating with the ultrasonic detection device. Meanwhile, the influence of constant impulse on the damage degree of coal-rock was compared. The results show that the damage degree of coal-rock increases with the increase of the impulse, and the damage fitting curve is upward concave, indicating that the coal sample tends to accelerating failure. Moreover, with the increase of axial pressure, the variation gradient of the damage degree of coal-rock tends to moderate and the cumulative damage degree decreases under the same impulse, and the impact resistance of coal-rock increases. When the impulse is constant, the damage degree of coal-rock increases with the number of impact, and the damage curve is upward convex, indicating that coal-rock has a tendency to slow down the damage. The cumulative damage degree of coal-rock decreases with the increase of axial pressure, and the number of impact needed to destroy coal-rock is increased. In addition, the damage model of coal-rock was proposed, and the criterion of coal-rock damage was obtained, which shows that the damage degree of coal-rock increases with the increase of impact load and decreases with the increase of static axial load.

scholarly journals Axial Impact Load of a Concrete-Filled Steel Tubular Member with Axial Compression Considering the Creep Effect

Materials ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3134 ◽  
Author(s):  
Tao Lan ◽  
Guangchong Qin ◽  
Jinzhao Zhuang ◽  
Youdi Wang ◽  
Qian Zheng ◽  
...  
Keyword(s):  
Impact Load ◽  
Slenderness Ratio ◽  
Concrete Strength ◽  
Pressure Ratio ◽  
Impact Resistance ◽  
Axial Pressure ◽  
Axial Impact ◽  
Creep Effect ◽  
The Impact ◽  
Peak Value

The dynamic loads acting on concrete-filled steel tubular members under axial impacts by rigid bodies were studied herein by FEM. The whole impact process was simulated and the time history of the impact load was obtained. The effects of eight factors on the axial impact load were studied; these factors were the impact speed, mass ratio, axial pressure ratio, steel ratio, slenderness ratio, concrete strength, impact position, and boundary conditions. Besides this, the effects of concrete creep on the impact load were also considered by changing the material parameters of the concrete. The results show that axial impact load changes with time as a triangle. The peak value of impact load increases and the impact resistance improves with the growth of the axial pressure ratio, steel ratio, slenderness ratio, and concrete strength after creep occurs. As the eccentricity of the axial impact acting on a concrete-filled steel tubular member increases, the peak value of the impact load decreases. The enhancement of constraints at both ends of the member can improve the impact resistance. The creep reduction coefficients for the peak axial impact load of a concrete-filled steel tubular member under axial compression and considering the creep effect over 6 months and 30 years are 0.60 and 0.55, respectively. A calculation formula for the peak value of impact load was suggested based on the existing formula, and its accuracy was proved by finite element calculation in this study.

scholarly journals Applicability of Thermoplastic Elastomers to Impact Load Reduction in Sports Equipment

Proceedings ◽  
2020 ◽  
Vol 49 (1) ◽  
pp. 163
Author(s):  
Akihiro Matsuda ◽  
Shigeru Kawahara
Keyword(s):  
Impact Load ◽  
Damage Model ◽  
Thermoplastic Elastomer ◽  
Tensile Loading ◽  
Thermoplastic Elastomers ◽  
Load Reduction ◽  
Loading Test ◽  
Element Analysis ◽  
Hyperelastic Model ◽  
The Impact

In this paper, mechanical properties of thermoplastic elastomers were investigated to expand the applicability of thermoplastic elastomers to the impact load reduction for the sports equipment. The thermoplastic elastomers show both thermoplastic and elastomeric properties. These are expected to apply to the impact load reduction in sports equipment due to good processability and less-smell. In this study, thermoplastic elastomers were applied for monotonic and cyclic tensile loading tests. The thermoplastic elastomer (TPE) materials in this study were newly developed for the specific purpose of impact load reduction. The nonlinear hyperelastic model considering the viscosity and damage model was applied to the tensile loading test results. finite element analysis (FEA) results of TPE specimens with periodic geometric shapes to reduce impact load were investigated.

scholarly journals Simulation and Experimental Study on the Discontinuous Dynamic Impact on Unidirectional Confined Coal-Rock Damage

2019 ◽  
Vol 2019 ◽  
pp. 1-15
Author(s):  
Tao Wang ◽  
Hongbao Zhao ◽  
Yang Li ◽  
Huan Zhang ◽  
Nansong Ju
Keyword(s):  
Impact Velocity ◽  
Static Load ◽  
Impact Load ◽  
Cumulative Effect ◽  
Dynamic Impact ◽  
Loading Test ◽  
Microcrack Propagation ◽  
Impact Impulse ◽  
Coal Rock ◽  
Pendulum Impact

The deformation and the damage characteristics of coal and rock under different restraint static load and different impact velocity were studied with the FEM software LS-DYNA. Based on this, the influence of impact load on the damage of coal rock under one-dimensional constraint condition was studied by using the self-developed constrained pendulum impact dynamic loading test device and ultrasonic testing device. The results show that the deformation of coal and rock increases with the increase of impact velocity and decreases firstly and then remains constant with the increase of constraint static load; when the constraint static load exceeds the compression strength, the displacement increases rapidly and the coal collapses at a strike; the damage quantity of coal and rock has a cumulative effect, and the damage quantity increases with the increase of impact number; when the constraint static load is identical, the increase of impulse contributes to microcrack propagation, and the damage quantity of coal and rock accelerates with the increase of single impact impulse; when the impulse is identical, the constraint static load restrains the microcrack propagation, and the damage quantity of coal and rock decelerates with the increase of constraint static load; the complete damage quantity range of coal and rock is 0.65∼0.75. In order to fully destroy the coal and rock, if the single horizontal impulse is greater, the number of shocks needed is less; if the constrained static load is greater, the more impact times are needed.

IMPACT RESISTANCE PROPERTIES OF KEVLAR/GLASS FIBER HYBRID COMPOSITE LAMINATES

2015 ◽  
Vol 76 (3) ◽  
Author(s):  
Norazean Shaari ◽  
Aidah Jumahat ◽  
M. Khafiz M. Razif
Keyword(s):  
Glass Fiber ◽  
Hybrid Composite ◽  
Composite Laminates ◽  
Impact Damage ◽  
Impact Resistance ◽  
Impact Behavior ◽  
Slight Reduction ◽  
Depth Of Penetration ◽  
Damage Degree ◽  
The Impact

In this paper, the impact behavior of Kevlar/glass fiber hybrid composite laminates was investigated by performing the drop weight impact test (ASTM D7136). Composite laminates were fabricated using vacuum bagging process with an epoxy matrix reinforced with twill Kevlar woven fiber and plain glass woven fiber. Four different types of composite laminates with different ratios of Kevlar to glass fiber (0:100, 20:80, 50:50 and 100:0) were manufactured. The effect of Kevlar/glass fiber content on the impact damage behavior was studied at 43J nominal impact energy. Results indicated that hybridization of Kevlar fiber to glass fiber improved the load carrying capability, energy absorbed and damage degree of composite laminates with a slight reduction in deflection. These results were further supported through the damage pattern analysis, depth of penetration and X-ray evaluation tests. Based on literature work, studies that have been done to investigate the impact behaviour of woven Kevlar/glass fiber hybrid composite laminates are very limited. Therefore, this research concentrates on the effect of Kevlar on the impact resistance properties of woven glass fibre reinforced polymer composites.

scholarly journals Impact Resistance Analysis and Optimization of Variant Truss Beam Structure Based on Material Properties

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5847
Author(s):  
Xiaohao Li ◽  
Junqi Pan ◽  
Xingchen Zhou
Keyword(s):  
Simulation Analysis ◽  
Impact Load ◽  
Impact Resistance ◽  
Structure Design ◽  
Response Surfaces ◽  
Optimization Strategy ◽  
Buffer Effect ◽  
Characteristic Analysis ◽  
Beam Structure ◽  
The Impact

In order to meet the increasing application requirements with regards to structural impact resistance in industries such as mining, construction, aerospace engineering, and disaster relief and mitigation, this paper designs a variant truss beam structure with a large shrinkage ratio and high impact resistance. Based on the principle of the curved trajectory of scissor mechanisms, this paper conducts a finite element simulation analysis of the impact load on the truss beam structure, a theoretical analysis of the impact response and a relevant prototype bench-top experiment, completing a full study on the impact resistance mechanism of the designed variant truss beam structure under the impact load. In the paper, the buffer effect of the external load impact on the variant truss beam structure is analyzed from the perspective of the energy change of elastic–plastic deformation. This paper proposes an optimization strategy for the variant truss beam structure with the energy absorption rate as the optimization index through extensive analysis of the parameter response surfaces. The strategy integrates analyses on the response characteristic analysis of various configuration materials to obtain an optimal combination of component parameters that ensures that the strength of the truss beam structure meets set requirements. The strategy provides a feasible method with which to verify the effectiveness and impact resistance of a variant truss structure design.

scholarly journals Impact Response of Hammerhead Pier Fibrous Concrete Beams Designed with Topology Optimization

2020 ◽  
Author(s):  
Meivazhisalai Parasuraman Salaimanimagudam ◽  
Covaty Ravi Suribabu ◽  
Gunasekaran Murali ◽  
Sallal R. Abid
Keyword(s):  
Topology Optimization ◽  
Concrete Beams ◽  
Impact Load ◽  
Impact Resistance ◽  
Adaptive Mesh ◽  
Impact Response ◽  
Adaptive Meshing ◽  
Repeated Impact ◽  
Ductility Ratio ◽  
The Impact

Reducing the weight of concrete beams is a primary (beyond strength and durability) concern of engineers. Therefore, this research was directed to investigate the impact response of hammerhead pier concrete beams designed with density-based method topology optimization. The finite element topology optimization was conducted using Autodesk fusion 360 considering three different mesh sizes of 7 mm, 10 mm, and adaptive meshing. Three optimized hammerhead beam configurations; HB1, HB2, and HB3, respectively, with volume reductions greater than 50 %. In the experimental part of this research, nine beams were cast with identical size and configuration to the optimized beams. Three beams, identical to the optimized beams, were tested under static bending for verification purposes. In comparison, six more beams, as in the preceding three beams but without and with hooked end steel fibers, were tested under repeated impact load. The test results revealed that the highest flexural capacity and impact resistance at crack initiation and failure were recorded for the adaptive mesh beams (HB3 and HB3SF). The failure impact energy and ductility ratio of the beam HB3SF was higher than the beams HB1SF and HB2SF by more than 270 %. The results showed that the inclusion of steel fiber duplicated the optimized beam’s impact strength and ductility several times. The failure impact resistance of fibrous beams was higher than their corresponding plain beams by approximately 2300 to4460 %, while their impact ductility ratios were higher by 6.0 to 18.1 times.

Microstructure and Impact Load Performance of Friction Stir Welded Joint of AZ31B Magnesium Alloy

2020 ◽  
Vol 866 ◽  
pp. 54-62
Author(s):  
Hong Feng Wang ◽  
Sheng Rong Liu ◽  
Xiao Le Ge ◽  
Jia Fei Pu ◽  
Lei Bao ◽  
...  
Keyword(s):  
Friction Stir Welding ◽  
Magnesium Alloy ◽  
Impact Load ◽  
Base Material ◽  
Welding Parameters ◽  
Loading Test ◽  
Az31b Magnesium Alloy ◽  
Friction Stir ◽  
Joint Area ◽  
The Impact

10mm thickness AZ31B magnesium alloy was used as the friction stir welding object in this study. Different welding joints were obtained by setting different friction stir welding parameters. Metallographic analysis and impact loading test were carried out on the joint area. The experiment results show that (i) when the rotational speed of the stirring head is 600rpm and the welding speed is 120mm/min, the microstructure of the joint has the characteristics of compactness, thinning, and large-area twinning, which is beneficial to improve the plasticity of the joint area; (ii) the impact load of the joint is the highest, but lower than that of the base material, which is 95.5% of the base material; (iii) the fracture of impact specimen presents ductile fracture.

scholarly journals Experimental Investigation on Relations Between Impact Resistance and Tensile Properties of Cement-Based Materials Reinforced by Polyvinyl Alcohol Fibers

2019 ◽  
Vol 9 (20) ◽  
pp. 4434
Author(s):  
Ju Zhang ◽  
Pucun Bai ◽  
Changwang Yan ◽  
Shuguang Liu ◽  
Xiaoxiao Wang
Keyword(s):  
Polyvinyl Alcohol ◽  
Tensile Properties ◽  
Impact Load ◽  
Impact Resistance ◽  
Crater Diameter ◽  
Cement Based Materials ◽  
Weight Test ◽  
Ultimate Failure ◽  
Drop Weight Test ◽  
The Impact

Cement-based material is brittle and is easily damaged by an impact load with a few blows. The purpose of this paper is to study the relations between the impact resistance and tensile properties of cement-based materials reinforced by polyvinyl alcohol fiber (PVA-FRCM). A drop-weight test and uniaxial tension test were performed. The relations were studied based on the experimental results, including the relation between the blow number and the tensile stress at the first visible cracking (σc) and the relation between the blow number and the tensile strain at the ultimate failure (εf). Results showed that the blow number for the first visible crack for disc impact specimens increases obviously with the increase of σc of slab specimens. The crater diameter and blow number for ultimate failure of the disc specimens increase with the increase of εf of slab specimens. For the PVA-FRCM specimens with larger σc and εf, much more blows are needed to cause both the first visible crack and ultimate failure. Polyvinyl alcohol fibers can reinforce impact resistance and tensile properties of cement-based materials.

Rollover Analysis of Heavy Vehicle Bus

2014 ◽  
Vol 660 ◽  
pp. 633-636 ◽  
Author(s):  
Mohd Khir Mohd Nor ◽  
Muhammad Zulhusmi Dol Baharin
Keyword(s):  
Maximum Stress ◽  
Motor Vehicle ◽  
Motor Vehicle Accident ◽  
Impact Load ◽  
Heavy Vehicle ◽  
Loading Test ◽  
Stress Point ◽  
Impact Side ◽  
The Impact ◽  
Static Simulation

Rollover is motor vehicle accident that occurs when vehicle is tipping over onto its side or roof. Due to its fatality rate, the Malaysian government reinforced an Economic Commission for Europe of the United Nations (UN/ECE) Regulation no. 66 (R66) upon bus construction. This is to prevent the catastrophic consequences of rollover accidents. The R66 regulation provides an option of certification based on full-scale vehicle testing that maitaning the survival space. Therefore research that contribute to the development of safe transportation vehicle under rollover is really important. The physical prototype of rollover test can be simplified using simulation model. Using this motivation, the characteristic of heavy vehicle rolleover is investigated in this paper. The simulation was performed using ANSYS simulation tool and simplified by locating the position of the bus in unstable equilibriumm, just before it hit the ground. Another method is to perform a quasi-static loading test. The quasi-static simulation test was performed using impact load that directed towards the side of beam around the centre of frame body. The dynamic response due to rollover impact was determined using an Explicit Dynamic Analysis in ANSYS. The stress maximum stress first developed around the impact area before lag the stress stream to the opposite side. It can be observed that the maximum stress point is located at the middle structure of impact side. After few times of impact, the maximum stress starts to changes to the opposite side. Quasi-static simulation result in higher total deformation on impact side area. It also indicates high maximum stress point around the middle structure.

scholarly journals Effect of Three-dimensional Printing with Nanotubes on Impact Resistance

2019 ◽  
Author(s):  
Anne Schmitz
Keyword(s):  
Mechanical Properties ◽  
Lower Limb ◽  
Impact Resistance ◽  
Three Dimensional ◽  
Three Dimensional Printing ◽  
Impact Tester ◽  
The Impact ◽  
Dimensional Printing ◽  
Pendulum Impact ◽  
Pendulum Impact Tester

Abstract The types of biomedical devices that can be three-dimensional printed (3DP) is limited by the mechanical properties of the resulting materials. As a result, much research has focused on adding carbon nanotubes (CNT) to these photocurable polymers to make them stronger. However, there is little to no data on how CNTs affect the impact resistance of these polymers, an important property when designing and manufacturing lower limb prosthetics. The objective of this study was to expand the use of 3DP to prosthetics by testing the hypothesis that adding CNTs to a stereolithographic (SLA) photocurable resin will result in a cured polymer with increased impact resistance. Twenty-six total specimens: 13 with nanotubes and 13 without nanotubes, were printed on a Form2 SLA printer. Once all the specimens were printed, washed, and cured, the impact resistance was quantified using a pendulum impact tester in a notched Izod configuration. Contrary to the hypothesis, the specimens with SWCNTs (0.312 ± 0.036 ft*lb/in) had a significantly lower impact resistance compared to the non-SWCNT specimens (0.364 ± 0.055 ft*lb/in), U = 34.0, p = 0.004. This decreased impact resistance may be due to voids in the printed polymer around the aggregated nanotubes. Thus, SLA polymers still do not have the impact strength needed to be used for a full lower limb prosthetic.

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