Effect Of Impact Angle Research Articles

Honeycomb core failure mechanism of CFRP/Nomex sandwich panel under multi-angle impact of hail ice

The rudder of an airplane is fabricated as a sandwich panel and can potentially be damaged by hail ice. The dynamic responses of a CFRP/Nomex sandwich panel with barely any visible core damage under multi-angle impact of an ice sphere at various velocities are researched experimentally and by using numerical simulations at the mesoscale. The results show that the honeycomb core represents three types of failure modes: wrinkling, fracture of cell walls, and debonding of cell walls at the interface of two-glued-paper-walls (TGPW) due to resin failure. These failure modes exist at specific impact velocities and angles. This paper proposes a mesoscale numerical modeling method of a honeycomb structure to represent the debonding failure at the TGPW interface. In addition, the mechanical properties of these failures are revealed, as the wrinkling of the cell walls are caused by buckling and the fracture of the cell walls and debonding of the TGPW interface are caused by out-plane and in-plane shearing of cell walls. The results showed that the relationship between the denting and impact kinetic energy under multi-angle impact is linear with respect to the impact angle. The effects of impact angles on the contacting forces on a rigid wall and sandwich panel are presented as the amount of peak impact forces affected by the target material type. However, the intensity of the peak impact forces is rarely affected by the type of the target material. The peak impact force of nonvertical impact is greater than that of the normal impact when the normal components of the impact velocities are the same. This is because the impact angle affects the distribution of ice scatter fragments during the impact, and this generates different pressure distributions on the face sheet of the panel.

Investigation & characterization of plasma sprayed cermet coatings on special steel alloy for gas turbine applications

The gas turbines are the components which are commonly affected by severe high-temperature erosion wear due to impingement of solid particles entrained in the stream of fluid. The present investigation focuses on the applicability of plasma sprayed coatings for turbines by improving the erosion resistance of the base material. The present work includes high-temperature solid particle erosion behaviour of [35%(WC-Co)/65%(Cr3C2NiCr), [70%NiCrAlY + 30%TiO2] & [70%NiCrAlY + 25%Cr2O3 + 5%YSZ] coatings deposited by atmospheric plasma spray (APS) process. All the coating materials are considered by weight (%). The effect of impact angle on erosion performance of uncoated and coated specimens were comparatively studied by using the air-jet erosion tester (ASTM G76-13). The eroded surface morphology was analysed by using a porosity tests, microhardness values, scanning electron microscopy & X-ray diffraction analysis. All Coatings exhibits the ductile erosive mechanism at the temperature of 700 °C with severe plastic deformation. The NiCrAlY + TiO2 coating is more protective than the other two coatings in high temperature and erosion environments due to its higher ductility, homogenous microstructure, and lesser porosity of the coatings. However, uncoated MDN 420 steel exhibits lesser wear loss when compared to the coated substrates. This may be due to the alumina particles' embedment onto the coated surface, which might present a shielding effect against further material loss to occur.

Slurry erosion behaviour of Ni-Hard under various impact angle and speed

To Study wear analysis of slurry pump with an experimental condition is an economically costly and lengthy process. Therefore, wear study can be done on various laboratory tests such as Slurry pot tester, Coriolis wear tester, Whirling arm wear test device, particle impact jet test. To analyze of erosion wear rate of slurry pump material in different operating conditions is performed on slurry pot tester. In the latest pump the Ni-Hard is widely used material in the slurry transportation. The one of the major application of slurry pump made from Ni-Hard is in Thermal power plant for ash slurry transportation. In this paper an experimental work has been carried out to find the effect of impact angle and particle impact speed at 20% w/w slurry concentration of sand on the wear rate of the Ni-Hard material. From the experimental results it is found that as particle velocity increases erosion wear rate of the material is increases. It was also found that the erosion of the material increases with impact angle till 30° then the erosion of material decreases gradually.

Numerical Simulation of Impact Behavior of Ceramic Coatings Using Smoothed Particle Hydrodynamics Method

Abstract In this work, the impact behavior of an alumina spherical particle on alumina coating is modeled using the smoothed particle hydrodynamics (SPH) method. The effects of impact angle (0 deg, 30 deg, and 60 deg) and velocity (100 m/s, 200 m/s, and 300 m/s) on the morphology changes of the impact pit and impacting particle, and their associated stress and energy are investigated. The results show that the combination of impact angle of 0 deg and velocity of 300 m/s produces the highest penetration depth and largest stress and deformation in the coating layer, while the combination of 100 m/s and 60 deg causes the minimum damage to the coating layer. This is because the penetration depth is determined by the vertical velocity component difference between the impacting particle and the coating layer, but irrelevant to the horizontal component. The total energy of the coating layer increases with the time, while the internal energy increases with the time after some peak values, which is due to energy transmission from the spherical particle to the coating layer and the stress shock waves. The energy transmission from impacting particle to coating layer increases with the increasing particle velocity and decreases with the increasing inclined angle. The simulated impact pit morphology is qualitatively similar to the experimental observation. This work demonstrates that the SPH method is useful to analyze the impact behavior of ceramic coatings.

Simplified analysis of curvilinear penetration of free fall sphere projectile in soft soil

Free fall projectiles have been used in offshore engineering to determine in-situ undrained shear strength profiles of near-surface soft soils from accelerations recorded during penetrating. In doing so, however, only the equation of motion in the vertical direction has been formulated with the vertical acceleration by assuming vertical impact and penetration. In this study, the governing equations of curvilinear penetration of a sphere projectile are established with consideration of an angle of impact with soil surface. By treating the penetration process as an initial value problem, an algorithm is proposed for computing the trajectory, velocity and linear acceleration of penetration. The effects of impact angle, impact velocity and soil strength non-homogeneity on the penetration behavior are analyzed using a set of parameters reported in literature. The computed results of the final embedment depth and linear acceleration of sphere are shown to be in reasonably good agreement with published field data. Moreover, a new explicit equation is derived for determining the undrained shear strength of soil based on both vertical and horizontal linear accelerations. The accuracy of the undrained shear strength estimated by assuming vertical penetration is assessed. The impact angle is shown to have important influence on soil strength determination.

The effect of impingement angle on erosion wear characteristics of HVOF sprayed WC-Ni and WC-Cr3C2-Ni cermet composite coatings

The present study investigated the erosion wear behavior of WC-Ni and WC-Cr3C2-Ni cermet coatings deposited by high velocity oxy-fuel (HVOF) spray process on the substrate of 1Cr18Ni9Ti stainless steel. Microstructures and morphologies of the coatings were examined using SEM images, and x-ray diffractometer was used to analyze the phase composition of the powder and the coatings. The erosion test was carried out using home-made jet rig. In order to better fit the research background of this study, the erodent used for erosion was taken from the Yellow River, China. The coating is well combined with the substrate; and WC-Cr3C2-Ni coating consists of WC, Cr3C2 and Ni phases, WC-Ni coating consists of WC, W2C and Ni phases. Some mechanical properties of the two coatings were compared, WC-Cr3C2-Ni coatings have higher hardness to be compared with WC-Ni ones due to a lower binder content; and the elasticity modulus and nano-hardness values of the WC-Cr3C2-Ni coating are higher than that of the WC-Ni coating. The relationship between the wear performance of the coatings and impingement angle was obtained; and the erosion resistance of the coatings was analyzed. It was observed that WC-Cr3C2-Ni cermet coating exhibits higher erosion resistance under all testing conditions as compared with the WC-Ni cermet coating and 1Cr18Ni9Ti stainless steel. The results show that the erosion mechanism at low angle is mainly cutting, while erosion pits dominate at high angle for the coatings, moreover, plastic deformation could be observed in the case of the binder depletion and cracking found place. and the erosion mechanisms of the 1Cr18Ni9Ti stainless steel are mainly cutting and plastic deformation at low angle and high angle, respectively.

Flow and heat transfer characteristics of droplet obliquely impact on a stationary liquid film

The flow and heat transfer characteristics of a droplet obliquely impact on a stationary liquid film is numerically studied by using a coupled level set and volume of fluid method (CLSVOF). The effects of impact angle, Weber number, and film thickness are analyzed. As compared with the normal impact, the flow features and surface heat flux distribution for oblique impact are asymmetric and where the secondary droplets only can be observed on one side. Corresponding mechanisms have also been interpreted. The maximum value of the local surface heat flux decreases and moves to the right with the increase in impact angle, while the minimum local surface heat flux on both sides increases as the impact angle increases. With a greater Weber number or a thinner film thickness, the maximum local surface heat flux is higher, while the minimum local surface heat flux on both sides appears to be an opposite trend. In addition, the impact angle has little effect on the average surface heat flux.

Erosion wear behavior of benzoyl chloride modified areca sheath fiber reinforced polymer composites

Abstract The erosion wear properties of randomly oriented benzoyl chloride modified short areca sheath (AS) fiber reinforced polyvinyl alcohol (PVA) composites has been presented in this paper. The test specimens were prepared using various weights of fibers (0, 10, 20, 30 and 40%) by injection molding process. Wear behavior was studied using silica sand particle (200 ± 50 μm) as erodent taking impact angles (15, 30, 45, 60 and 90°) and impact velocities (48, 70, 82 and 109 m/s). The effect of impact angle and impact velocity of the erodent on erosion rate were studied and discussed. Pure PVA demonstrates greatest erosion rate at 30° whereas PVA/AS composites display most extreme erosion rate at 45° impact angle independent of fiber loading indicating semi ductile behavior. The minimum erosion was obtained at 10 wt% of fiber loading composites as compared with other fabricated composites. The eroded surface was further examined by scanning electron microscope (SEM) to study the eroded surface texture.

The derailment behaviour and mechanism of a subway train under frontal oblique collisions

Frontal oblique collision is more likely to cause train derailment and result in more serious consequences. In order to investigate the effect of impact angle on the derailment behaviour and mechanism of a subway train under frontal oblique collisions, a finite element model of train-rigid wall is established based on a four-section train running at 25 km/h. The oblique impact angle ranges from 6.34° to 45°. Numerical results indicate that middle coupler movements and lateral impact force are two main factors influencing derailment behaviours of the train during oblique collisions. For this reason, at 6.34°, the train has no risk of derailment. As the impact angle increases to 11.31°, train derails in saw-tooth mode and rear bogie of vehicle 1 derails. In oblique collisions of 15° and 20°, little-zigzag mode occurs with vehicle 1 and front bogie of vehicle 2 completely dropping from rail. However, once impact angle exceeds 25°, different movements of middle couplers have little influence on train derailment behaviours because impact force plays a leading role. In this condition, only vehicle 1 derails and the rest vehicles are not affected. Train derails in large displacement lateral mode. As to the analysis above, limiting yawing movement of middle couplers and improving lateral crashworthiness of vehicle structures are effective measures to decrease the risk of train derailment during oblique collisions.

Experimental and simulation studies of abrasive particles impacting monocrystalline silicon in suspension thin film flow field of ultrasonic polishing

In ultrasonic polishing (USP), when the gap between the polishing tool and workpiece is small enough, the suspension seeped into it can be considered as suspension thin film (STF). STF flow field provides a periodic oscillation condition for abrasive particles, which can improve abrasive particle cutting performance by changing its behavior. It is very effective for improving the polishing efficiency and surface quality of hard-to-machine materials. However, the interaction behavior of target material, STF flow field, and abrasive particle in USP has rarely been studied. In this paper, to fulfill a fundamental understanding of this field, the behavior of abrasive particles impacting monocrystalline silicon in STF flow field is investigated by experimental and simulation methods. At macro-level, through the study of ultrasonic amplitude, abrasive particle size, and polishing tool rotational speed in USP experiments, the positive role of STF flow field has been revealed, and the change characteristic of surface roughness is obtained. The computational fluid dynamics (CFD) simulation results show that strong transverse shear flow is formed in STF, which plays a major role in material removal. At micro-level, novel mathematical models of plastic deformation and brittleness removal and material removal mechanism of STF flow field are proposed. Comprehensive analysis of blunt and sharp abrasive particles impacting monocrystalline silicon is implemented through finite element method (FEM), which includes the effect of abrasive particle size on material removal rate (MRR), kinetic energy change of abrasive particle, force analysis of impact, the effect of impact angle, and polishing tool rotation on MRR. The final results show FEM simulation results are consistent with that of CFD simulation and experiments, which is of great significance to reveal the behavior principle of abrasive particles in STF and guide the actual production.

Influence of impact angle on size distribution of fragments in hypervelocity impacts

When aluminum alloy 2017-T4 spheres strike thick aluminum alloy 6061-T6 targets at 4 km/s, the size of fragments collected from a test chamber was measured and the effects of impact angle on the size and projected area of the fragments were examined. Impact angle clearly affected the size distribution and projected area distribution of the fragments. The cumulative number of fragments as a function of fragment length and projected area was proportional to the normal component of the impact velocity raised to the power 1.5. When the cumulative number on the vertical axis was divided by the normal component of the impact velocity raised to the power 1.5, experimental formulas with respect to fragment length and projected area were proposed using a bilinear exponential distribution function. The crater shapes on the targets were also examined, as were the area and shape of the indentations created by fragment particles on the witness plate. Their relationship to fragment size distribution was discussed. These results will assist in the revision of ISO 11227 with respect to oblique impact conditions.

On the critical flow velocity for erosion-corrosion in local eroded regions under liquid-solid jet impingement

The eroded surface of 2205 duplex stainless steel after liquid-solid jet impingement can be divided into three regions according to the severity of erosion-corrosion damage. The erosion-corrosion behavior for different local eroded regions was investigated using surface profile and potentiostatic polarization measurements. The results show that the critical flow velocity of these three regions is 13 m/s, 11 m/s and 15 m/s, respectively. The region with a lower critical value is more sensitive to erosion-corrosion damage with the increase of jet flow velocity showing much higher erosion-corrosion damage. The combined effect of impact angle and impact velocity of solid particles is the main reason causing the difference of critical flow velocity for different local eroded regions.

Effect of Impact Angle and Rotational Motion of Spherical Blocks on the Coefficients of Restitution for Rockfalls

The coefficients of restitution are among the most important parameters in rockfall trajectory modelling. However, they are difficult to obtain, they depend on many parameters and they present a significant variation even for similar geotechnical and kinematic conditions. Many definitions for the coefficients of restitution exist, but there is no agreement on which describes better the response of a block to an impact. In this paper, an extensive experimental investigation is presented, consisting of 600 oblique impact tests and the various coefficient of restitution definitions are assessed, with an emphasis on the effects of impact angle and angular velocity. These tests follow on the research presented in Asteriou and Tsiambaos (Int J Rock Mech Min Sci 106:41–50, 2018), where free-fall tests were performed to address the effects of impact velocity, block mass and material type. It was found that all those parameters affect significantly the coefficients of restitution. Moreover, an empirical model was proposed to estimate the coefficient of restitution for central impacts. The applicability of this model is extended for oblique impacts based on the results of the tests presented in this paper.

Multi-phase smoothed particle hydrodynamics modeling of supercooled large droplet dynamics for in-flight icing conditions

Understanding the dynamics of a single large water droplet is needed for accurate simulations of the in-flight icing phenomenon. Obtaining information on the ratio of ejected to deposited water and the post-impact droplet distribution should improve the numerical modeling of the bulk of impinging droplets. In this study, a weakly compressible multi-phase Smoothed Particle Hydrodynamics (SPH) method with shifting algorithm and surface tension model is presented to simulate the single droplet dynamics. The validity of the approach has been proved by modeling the classical problems of Rayleigh–Taylor instability, dam break, and droplet formation by comparing against other numerical and experimental data in the literature. Finally, droplet impingement on a liquid film and dry solid surface has been simulated and compared against the experimental data. The effect of impact angle and film thickness on the crown formation is studied to demonstrate the importance of modeling SLD impingement for in-flight icing conditions.

Effect of Impact Angle on the Erosion Rate of Coherent Granular Soil, with a Chernozemic Soil as an Example

It has been shown in experiments in a hydraulic flume with a knee-shaped bend that the rate of soil erosion more than doubles at the flow impact angles to the channel side from 0° to 50°. At higher channel bends, the experiment could not be performed because of backwater. Results of erosion by water stream approaching the sample surface at angles between 2° and 90° are reported. It has been found that the maximum erosion rate is observed at flow impact angles of about 45°, and the minimum rate at 90°. The minimum soil erosion rate is five times lower than the maximum erosion rate. This is due to the difference in the rate of free water penetration into the upper soil layer, and the impact of the hydrodynamic pressure, which is maximum at the impact angle of 90°. The penetration of water into the interaggregate space results in the breaking of bonds between aggregates, which is the main condition for the capture of particles by the flow.

Investigation on effect of using rubber as core material in sandwich composite plate subjected to low velocity normal and oblique impact loading

In this article, the structural performance of composite plate under low velocity impact is studied. Two forms of layup sequence namely jute-epoxy laminate (JE) and jute-epoxy-rubber sandwich (JE-R-JE) are considered for evaluation. Special emphasis is provided for evaluating the influence of normal and oblique loading. The various dynamic parameters such as energy, peak load, and deformation are analysed in detail to study the effect of impact angle on both laminate and sandwich. Stress analysis of both the laminate and sandwich structure is carried out to discuss the effect of introducing rubber as a core material. The results reveal that using rubber as a core material has a significant effect on energy absorption. In addition, it is noticed that increasing the angle of impact yields better performance of the composite plate. The results presented here may serve as benchmark for the effective utilization of composite plates in low velocity impact applications.

Effect of Impingement Angle on Erosion Resistance of HVOF Sprayed WC-10Co-4Cr Coating on CA6NM Steel

In the present investigation, WC–10Co–4Cr coating was deposited by high velocity oxy-fuel (HVOF) process on CA6NM hydro turbine steel to improve its erosion resistance. The coating was characterized in term of crossectional microstructure, phase, microhardness and fracture toughness using a field emission scanning electron microscope (FESEM), X-ray diffractometer and microhardness tester respectively. Solid particle erosion resistance of the substrate and coating were evaluated by air jet erosion tester at two different impingement angles (30° and 90°). Coating microstructure has shown a homogeneous and well-bonded laminar morphology. The microhardness of the coating was observed more than three times higher than CA6NM substrate. This resulted in significant improvement in erosion resistance of coated CA6NM steel at both impingement angles.

Effect of impingement angle and WC content on high temperature erosion behavior of SiC-WC composites

Hot pressed dense SiC-(0, 10, 30 or 50wt%)WC composites were subjected to erosion against SiC particles at 800°C. Effects of WC content and angle of impingement (30°, 60° or 90°) on the erosion performance of composites were evaluated. Erosion rate ranged from 2.1×102mm3/kg to 7.7×102mm3/kg with varying WC content or angle of impingement. The erosion rate of the composites increased with increasing the impingement angle from 30° to 90°, and decreased with WC content up to 30wt%. Minimum and maximum erosion wear rates were obtained for SiC-30wt% WC composites at 30° and for SiC-50wt% WC composites at normal impact, respectively. Grain fracture and pull-out were observed as major mechanisms of material removal for the composites. Decreased angle of impingement led to reduced grain fracture and pull-out, and hence reduction in material removal. Owing to increased fracture toughness with incorporation of WC particles, the composites showed less fracture and removal of WC particles up to 30wt% reinforcement.

A Study on Slurry Erosion Behavior of High Chromium White Cast Iron

High chromium white irons (HCCIs) are used extensively throughout the mineral processing industry to handle erosive and corrosive slurries. This study is an investigation of the effect of impact angle and velocity on slurry erosion of HCCI. The tests were carried out using a rotating whirling-arm rig with particle concentration of 1 wt. %. Silica sand which has a nominal size range of 500–710 μm was used as an erodent. The results were obtained for angles of 30 deg, 45 deg, 60 deg, and 90 deg to the exposed surface and velocities of 5, 10, and 15 m/s. The highest erosion resistance of HCCI was at normal impact and the lowest at an angle of 30 deg, irrespective of velocity. The low erosion resistance at an oblique angle is due to large material removal by microcutting from ductile matrix and gross removal of carbides. The effect of velocity, over the studied range from 5 m/s to 15 m/s, on the increase in the erosion rate was minor. The change of impact velocity resulted in changing the slurry erosion mechanisms. At normal incidence, plastic indentation with extruded material of the ductile matrix was the dominant erosion mechanism at low impact velocity (5 m/s). With increasing impact velocity, the material was removed by the indentation of the ductile matrix and to smaller extent of carbide fracture. However, at high impact velocity (15 m/s), gross fracture and cracking of the carbides besides plastic indentation of the ductile matrix were the dominant erosion mechanisms.

The Effect of Impact Angle of the Particle on Solid Particle Wear Properties of Basalt Base Glass-Ceramics

The Effect of Impact Angle of the Particle on Solid Particle Wear Properties of Basalt Base Glass-Ceramics