Experimental Study on Cement Clinker Particles under Impact Force
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In order to further study the impact crushing mechanism of cement clinker, the impact experiment has been carried out at different impact angles. Impact crushing curves, acoustic emission signal and peak impact force and impact fracture morphology have been systematically studied. It is shown that each impact crushing curve includes an inertia peak and an actual impact peak. AE signal directly reflects the crack initiation and propagation during the process of impact experiment. With the increase of impact angle, the average value of peak impact force decreases. The peak impact force value reaches the minimum at 75 °. The experiment results will offer a successful alternative to the low – energy grinding of cement clinker.Keywords:
Impact
Impact energy
Acoustic Emission
Although numerous studies on the impact response of laminated composites have been conducted, there is as yet no agreement within the composites community on what parameter or parameters are adequate for quantifying the severity of an impact event. One of the more interesting approaches that has been proposed uses the maximum contact force during impact to quantify the severity of the impact event, provided that the impact velocity is sufficiently low. A significant advantage of this approach, should it prove to be reliable, is that quasi-static contact loading could be used to simulate low velocity impact. In principle, a single specimen, loaded quasi-statically to successively increasing contact loads could be used to map the entire spectrum of damage as a function of maximum contact force. The present study had as its objective assessing whether or not the maximum contact force during impact is a suitable parameter for characterizing an impact. The response of [+/-60/0(sub 4)/+/-60/0(sub 2)](sub s) laminates fabricated from Fiberite T300/934 graphite epoxy and subjected to quasi-static contact loading and to low velocity impact was studied. Three quasi-static contact load levels - 525 lb., 600 lb., and 675 lb. - were selected. Three impact energy levels - 1.14 ft.-lb., 2.0 ft.-lb., and 2.60 ft.-lb. - were chosen in an effort to produce impact events in which the maximum contact forces during the impact events were 525 lb., 600 lb., and 625 lb., respectively. Damage development was documented using dye-penetrant enhanced x-ray radiography. A digital image processing technique was used to obtain quantitative information about the damage zone. Although it was intended that the impact load levels produce maximum contact forces equal to those used in the quasi-static contact experiments, larger contact forces were developed during impact loading. In spite of this, the damage zones developed in impacted specimens were smaller than the damage zones developed in specimens subjected to the corresponding quasi-static contact loading. The impacted specimens may have a greater tendency to develop fiber fracture, but, at present, a quantitative assessment of fiber fracture is not available. In addressing whether or not contact force is an adequate metric for describing the severity of an impact event, the results of this study suggest that it is not. In cases where the quasi-static load level and the maximum contact force during impact were comparable, the quasi-statically loaded specimens consistently developed larger damage zones. It should be noted, however, that using quasi-static damage data to forecast the behavior of impacted material may give conservative estimates of the residual strength of impacted composites.
Impact
Impact energy
Contact force
Quasistatic loading
Contact Mechanics
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This study presents the effects of temperature, impact energy, and specimen thickness on low-velocity impact (LVI) and compression-after-impact (CAI) behaviors of composites. LVI tests were conducted by an impact test machine at 20 °C and low temperatures. CAI tests were applied to the specimens at 20 °C. Studies have revealed that a drop in temperature results in an up to 40% increase in maximum contact force. Impact damage increases significantly as impact energy increases for thick specimens. The strength of CAI reduces with a drop in temperature and an increase in impact energy while increasing with a rise in thickness.
Impact energy
Impact
Drop Impact
Impact resistance
Compression test
Drop test
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Impact
Impact energy
Limiting
Impact resistance
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The low velocity impact response of sandwich panels at different energy levels has been investigated by conducting drop-weight impact tests using an instrumented falling-weight impact tower. Impact parameters like maximum impact force and the extent of the damage were evaluated and compared for different types of sandwich panels. Finite elements simulations have been undertaken using the LS-DYNA software; the results of FE simulations have a good agreement with the experiments. It shows that, the impact force increased with thickness of face-sheets and foam core, the extent of the damage increased with the impact energy, sandwich panels with steel face sheet has a good impact resistance in comparison with sandwich panel with aluminum face sheets.
Impact energy
Impact
Impact resistance
Sandwich panel
Drop Impact
LS-DYNA
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Impact energy
Impact
Low energy
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This paper presents research into the energy balance of stressing conveyor belts by impact processes. Research is described in the areas of measuring the resistance of conveyor belts to puncture, the impact process, and the effect of changes to the impact height on the tensile and impact forces. Measurements were performed on a rubber–textile belt with a polyamide carcass. Hammers with pyramidal and spherical impactors were used to compare the resistance of the examined conveyor. Values were obtained for the maximum energies for the selected impact heights and the residual positional energies for the measured bounce heights. The difference between these energies represents the impact energy. The results confirmed that the impact energy of a hammer with a pyramidal impactor is greater than the impact energy of a hammer with a spherical impactor, while this difference increases with increasing impact height. The shape of the pyramidal impactor simulates sharp-edged materials, which is the cause of greater damage in the tribological interaction with the conveyor belt. This paper provides information for determining the limit conditions for setting appropriate impact heights depending on the weight of the material transported using a given belt conveyor.
Hammer
Impact energy
Impact
Conveyor belt
Impact resistance
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Because of the limitations that are experienced when trying to perform Charpy and Izod impact tests, the drop weight impact test is preferred over the more conventional impact methods to determine whether the material is brittle or ductile. The drop weight impact technique indicates the conditions under which real-life components would be subject to impact loading. In this study, a drop-weight impact instrument has been designed and manufactured using a dropping weight which impacts the specimens, falls through a perpendicular guide tube with a high range of impact energy levels. Force - deformation and acceleration –time graphs, could be determined by using various sensor systems were installed to calculate the impactor's velocity and the magnitude of the impact force. Consequently, the energy absorption of different materials can be measured and the damage resistance could be indicated.
Charpy impact test
Impact
Impact energy
Impact resistance
Drop Impact
Brittleness
Penetration (warfare)
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The impact programmer for impact test was designed and the impact analysis was conducted. The effects of the material and geometric parameters on the impact force and pulse shape were investigated. The impact characteristics were examined by experimental and finite element method. The impact test was conducted with free drop impact tester. The ABAQUS/Explicit 5.5 version was used for finite element analysis. The geometric parameters of the conical and dome type impact programmer were analyzed. The polyurethane impact programmers were fabricated and tested. The effects of the hardness and thickness of the impact programmer were studied. The peak acceleration and time duration of impact programmer have close correlation with the hardness, impact energy and thickness of the impactor. The experiment was good agreement with analytical predictions. The impact pulse shape generated with polyurethane impact programmer was half sine shape. The maximum impact force was proportional to impact energy. The impact acceleration was decreased with thickness of impact programmer. The maximum impact time duration level was about 2 msec.
Impact
Impact energy
Programmer
LS-DYNA
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In order to further study the impact crushing mechanism of cement clinker, the impact experiment has been carried out at different impact angles. Impact crushing curves, acoustic emission signal and peak impact force and impact fracture morphology have been systematically studied. It is shown that each impact crushing curve includes an inertia peak and an actual impact peak. AE signal directly reflects the crack initiation and propagation during the process of impact experiment. With the increase of impact angle, the average value of peak impact force decreases. The peak impact force value reaches the minimum at 75 °. The experiment results will offer a successful alternative to the low – energy grinding of cement clinker.
Impact
Impact energy
Acoustic Emission
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To investigate the low-speed impact response of the BR1200HS steel and AA6082 aluminum alloy self-piercing riveted (SPR) joint, low-speed impact tests with impact energies of 2.5 J, 5.0 J, 7.5 J, 10.0 J, 12.5 J, 15.0 J, 20.0 J, and 30.0 J were conducted utilizing a drop hammer impact tester. The results show that with the increased impact energy, the visual breakages of the SPR joints become more severe. The maximum impact energy the joints can sustain ranges from 10.0 J to 12.5 J. When the impact energy is less than 12.5 J, the contact force/energy–time curves show similar variations. Moreover, as the impact energy increases, total uptake energy value (Et), maximum uptake energy value (Ef), and maximum contact force (Fm) of the joints increase gradually. The low-speed impact energy has little effect on the maximum static tensile force of the impacted joints. However, the residual energy values decrease with the increase in impact energy. The tensile failure form of the joints is the pulling out of the rivets from the lower plates, and the low-speed impacts have no significant effect on the tensile failure form of the joints.
Impact energy
Hammer
Impact
Drop Impact
Rivet
Contact force
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