Effect Of Impact Angle Research Articles

Angled shots onto body armour using 9 mm ammunition: the effect on potential blunt injury

IntroductionSome military specialists wear body armour that is more similar to police armour and provides protection from ammunition fired from pistols. During ballistic testing, these armours are mounted on a...

Erodent Impact Angle and Velocity Effects on Surface Morphology of Mild Steel

Erosion of the flow-lines due to sanding is a problem of practical significance in almost all areas of oil and gas and other closely related industries. The presented work was aimed at investigating the effects of sand impact angle and velocity on the erosion rate of the flow-lines. An in-house built sand blasting technique was used to erode the representative mild steel plates with accelerated sand stream. Scanning Electron Microscopy (SEM), Energy-dispersive X-ray Spectroscopy (EDS) and weight loss (WS) techniques were used to quantify the effect of impact angle and velocity on the erosion rate of the exposed surface. The experimental data revealed an increasing trend in erosion rate with rise in sand velocity and impact angle. The highest erosion rate of 8.58 ± 0.1 mm/year was calculated at an impact angle of 90̊ and velocity of 20 m/s. At smaller impact angles, magnitude of the sand impact force on the target surface was reduced and consequently the erosion rate. The overall erosion rate, investigated at the particle velocities of 10 m/s and 20 m/s, was decreased from 6.59 ± 0.18 to 1.88 ± 0.09 and 8.58 ± 0.1 to 2.91 ± 0.11, respectively, with a decrease in the impact angle from 90̊ to 30̊.

Erosion Behavior of Steel Pipes Carrying of Some Iraqi Crude Oils

This paper deals with erosion that is defined as a process of progressive removal of material from a target surface due to repeated impacts of solid particles for the special case of two phases (liquid and solid). Experimental investigation dependence on erosion rate in different Iraqi oils obtained from Baghdad East Field (Al-Khaseb oil (Kh) and Al-Tanoma oil (T)) and from Al- Durra Refinery (Al-Stratege oil (ST)). The effect of impact angle and testing time on erosion rates has been analyzed. An erosion devise is fabricated and special fixtures havebeen developed to conduct erosion tests at various impactangles (30°, 45°, 60°,and 90°). Experimentshave been conducted in oil in absence and presence sandof concentration (1.74 wt. %) with three particle sizes (600 µm, 850 µm and mixture of two) at the velocity of (8.4 m/s). The results indicated that the increasing of impact angle led to decreasing erosion rate.

Effect of Impact Angle on Erosive Abrasive Wear of Ductile and Brittle Materials

Effect of Impact Angle on Erosive Abrasive Wear of Ductile and Brittle Materials

Effect of nose shape on semi-armor-piercing warhead penetration performance

The numerical simulations of different head shape semi-armor-piercing warheads penetrating thin steel target are done using the finite element software ANSYS/LS-DYNA, and the whole process of different nose shape semi-armor-piercing warheads vertically penetrating the thin steel plate is compared. Besides, the influence of impact angle on penetration performance of three different nose shape projectiles is researched. The analysis results indicate that the nose shape has a significant influence on semi-armor-piercing warhead penetration performance. The effect of impact angle on the three kinds of projectiles’ residual kinetic energy and deflection is different. The research results provide references for designing of warhead and battlefield damage assessment.

Effect of Impact Angle on the Erosion–Corrosion Behavior of AISI 420 Stainless Steel in 3.5 wt.% NaCl Solution

Erosion, erosion–corrosion, and synergistic behaviors of AISI 420 stainless steel were studied in 3.5 wt.% NaCl solution containing silica sand with the size of 250–500 μm as erodent particle. The erosion and erosion–corrosion tests were carried out according to ASTM G11909 standard and the synergism was calculated. The tests were performed using a slurry jet apparatus at a jet velocity of 6.5 m/s, sand concentration of 90 g/l, and various impinging angles of 20 deg–90 deg. Scanning electron microscope (SEM) was used to study the eroded surfaces and erosion mechanisms. The SEM images showed that under low impacting angles, cutting deformation was the main erosion mechanism while impact and work hardening could be responsible for material removal at high impacting angles. The results showed that the maximum erosion–corrosion and synergism rates occurred at an impingement angle of about 50 deg while the maximum pure erosion rate was obtained at impingement angle of about 35 deg. Energy dispersive spectrometry (EDS) analysis showed that an oxide layer was formed on the surfaces of the samples during erosion–corrosion tests. This oxide layer could make the surface more brittle and could lead to an increment of about 15 deg in the angle of the maximum removal rate. The formation and the subsequent removal of the nonprotective oxide layer as well as possible initiation and propagation of pits during erosion–corrosion tests could lead to higher erosion–corrosion rate compared to pure erosion resulting in a positive synergism under the conditions tested.

Theoretical and Experimental Study on the Effects of Impact Angle on the Performance of Kevlar Woven Fabric Rubber Composite Armor against Shaped Charge Jet Impact

AbstractKevlar woven fabric rubber composite armor (WFRCA) is a type of add‐on armor that usually consists of two steel plates with two Kevlar woven fabrics and a rubber layer in between. In this study, a theoretical model was developed to analyze the effect of the impact angles on the performance of the Kevlar WFRCA against the shaped charge jet impact. The calculation of the precursor length was discussed in detail. A series of X‐ray experiments were conducted to analyze the disturbance mechanism and precursor length of the Kevlar WFECA against the shaped charge jet under different impact angles. Theoretical and experimental analyses showed that the greater the impact angle, the higher the tip velocity of the precursor and the shorter the precursor length. A microscopic study of the edge of the Kevlar woven fabric, rubber, and steel plates after the shaped charge jet impact was also conducted to evaluate the structure and composition. Several broken Kevlar fibers were embedded in the steel plate and the moving jet. This phenomenon can be used to further investigate the disturbance mechanism of the Kevlar WFRCA against the shaped charge impact.

Numerical and experimental analysis of dynamic oblique impact: Effect of impact angle

Surface failures under dynamic oblique impact occur in many mechanical systems. In automobile engine, valve seat insert works under complex vibrating conditions. This leads persistently to the evolution of contact pressure, stress and strain as a function of time. By simplifying the system to a ball-on-flat configuration, the contact dynamic behavior was investigated as a function of impact angle. In order to better understand experiments on the experimental bench test, a finite element model was developed. Experimental and numerical results show an evolution from permanent reciprocating sliding at low angles to an intermittent motion called multi-impacts at higher angles. Experimental electrical contact resistance measurements confirm the observed evolutions. As a consequence, shearing stress is reduced when plastic deformation is increased with multi-impacts.

Sticking/rebound criterion for collisions of small adhesive particles: Effects of impact parameter and particle size

The collision-sticking phenomenon among micron-sized particles is ubiquitous in nature and plays an important role in formation of particle agglomerates or deposits. In this paper, a validated 3D JKR-based discrete-element method (DEM) is employed to investigate oblique collisions of micron-sized particles. Special attention is paid to the effects of impact parameter and particle size on the sticking/rebound criterion and energy dissipation pathways. Various energy dissipation mechanisms, including viscoelastic effect, sliding resistance and rolling resistance, are incorporated in our DEM model. Based on our simulation results, the temporal evolution for the collision process is revealed in detail to establish a deeper understanding of collision dynamics. Moreover, two regimes are clarified according to the effect of impact angles on the sticking criterion. In the low impact angle regime, the normal critical velocity VCN keeps as a constant. While in the regime of high impact angle, VCN rapidly drops. Furthermore, the strong effect of particle size ratio on the critical velocity is also analyzed. This effect can be well described by the dimensionless adhesion parameter, Ad. Finally, a generalized formula is drawn as the sticking/rebound criterion for collisions of fine particles, which can be readily implemented in computational fluid dynamics (CFD) codes.

FEM analysis on the abrasive erosion process in ultrasonic-assisted abrasive waterjet machining

In this work, a finite element method (FEM) explicit dynamic simulation was employed to investigate the abrasive erosion process in ultrasonic-assisted abrasive waterjet (AWJ) machining. Johnson-Holmquist ceramic material model with failure criteria was utilized to realize the deletion of the failure elements for the simulation of material removal. The effects of impact angle and particle shape on the erosion rate were analyzed. The residual stress in workpiece induced by the erosion under the vibration condition was compared to that under the non-vibration condition. Furthermore, the ultrasonic-assisted erosion processes of multiple particles under different overlapping conditions on the impact areas were simulated. The simulation results show that the application of vibration can effectively improve the erosion rate and influences the contact process between the particle and the workpiece surface. The residual stress distribution in the section of workpiece parallel to the vibration direction is not symmetric under the vibration condition, which is quite different from the nearly symmetric one obtained without vibration.

Experimental Investigation of Erosion of Stainless Steel by Liquid-solid Flow Jet Impingement

Erosion of pipeline has in long time been an important issue due to the high particle production rate and watercut in the maturing assets. The present study has been conducted to assess the performance of stainless steel and the effect of various working conditions under high velocity (20ms-1) of liquid-solid jet impingement in various types of media containing 1.5wt% particles in normal water. Cumulative mass loss vs. exposure time was used to evaluate the erosion rate of the stainless steel. The surface and cross-sectional morphologies before and after the erosion tests were observed by scanning electron microscopy (SEM) to illustrate the evolution of erosion process. The effect of fluid impact angle on stainless steel depends on the competitive effect of normal stress and shear stress. Under normal impact, the surface film would be broken and damaged, but still remain on the electrode surface to provide somewhat protection. With the decrease of impact angle, shear stress becomes dominant, and it would thinner and even completely remove the film. The effects of impact angle on steel surface status and erosion rate are confirmed by surface morphology observation.

Effect of impact angle and testing time on erosion of stainless steel at higher velocities

Abstract Erosion is vitally important in aerospace and petrochemical industries, especially when the targets such as flight engines, gas control valves etc are subjected to high speed in an environment containing sand particles. A new erosion test rig, with a capability of producing a velocity greater than Mach 3, was built up to cater to this purpose. Results obtained from stainless steel testing showed that erosion rate was saturated at 120 s and reduced subsequently. In addition, the results of erosion rates at different impact angles indicated that severe erosion maximizes at an impact angle of 40°. Further, erosion profiles showed different erosion effects on the sample surface. Surface roughness increased with respect to time and peaked at 45°. Investigation into surface microstructure revealed different erosion mechanisms associated with different impact angles. The erosion mechanism transition from micro-plowing to indentation induced plastic deformation took place from low to high impact angles. Further, computational fluid dynamic model was used to compare with experimental results.

Effect of impact angle on the slurry erosion-corrosion of Stellite 6 and SS316

This study is an investigation of the effect of impingement angle on slurry erosion-corrosion of Stellite 6 manufactured by sand casting, lost wax casting and SS316. The tests were performed using an impingement rig in which a slurry with 3.5% NaCl and 1.177g/l suspended angular sand particles at 19m/s were recirculated for 1 h. The results were obtained for angles of 20°, 45°, 60° and 90° to the exposed surface. Post-experimental analysis using light microscopy, surface profiling and SEM assisted with clarification of the wear mechanisms and assessment of the severity of surface damage. Stellite 6 consistently exhibited superior wear resistance compared with SS316. The most severe regime for SS316 was experienced at low angle of impingement, 45°, due to its ductility. Alternatively, the brittle network of chromium carbides showed significant impact on the behavior of cast Stellite 6 under solid-liquid impingement with the most critical erosion-corrosion damage occurring at 60°.

Numerical investigation of heat transfer enhancement in a fin and tube heat exchanger using vortex generators

In presented work, numerical analysis of heat transfer and pressure drop using vortex generators in fin and flat tube heat exchanger has been presented. Conjugate heat transfer 3D numerical model has been developed and successfully carried out. Rectangular winglets were set in pairs, with downstream orientation. The effects of impact angles of 5°, 10° and 20° as well as winglet height were examined through Nu number and j/f factor. Reynolds number is ranged from 350 to 2200. The numerical results showed that in the range of the present study, the variation of these parameters can result in the increase of heat transfer but with a penalty of pressure drop. Pressure drop increases for larger impact angles and with winglet height. Optimum heat transfer without significant pressure drop increase gives the vortex generator geometry of 0.64 × 1.92 mm (i.e. winglet height equals 2/3 fin spacing) with impact angle 10°.

Liquid Sheet Formed by Impingement of Two Viscous Jets

Impinging-jet injectors are commonly used in liquid-propellant rocket engines. Previous theoretical studies on sheets formed by two impinging liquid jets have largely ignored the affect of liquid viscosity, however, several experimental results have illustrated that liquid viscosity could greatly influence sheet characteristics. This paper proposes an improved theoretical analysis model for two viscous liquid impinging jets, in which viscosity and energy dissipation are taken into account; experiments were also performed to validate the theory. Furthermore, based on this model, the effects of impingement angle, jet velocity profile, Weber number, and Reynolds number on sheet characteristics, such as sheet shape, thickness, and velocity distribution, were investigated.

Stepwise Erosion as a Method for Investigating the Wear Mechanisms at Different Impact Angles in Slurry Erosion

In the present work, stepwise erosion technique was carried out to investigate in detail the influence of impact angle on the erosion process of AISI 5117 steel. The number of impact sites and their morphologies at different impact angles were investigated using scanning electron microscope (SEM) examination and image analysis. The tests were carried out with particle concentration of 1 wt. %, and the impact velocity of slurry stream was 15 m/s. Silica sand—which has a nominal size range of 250–355 μm—was used as an erodent, using whirling-arm test rig. The results have shown that the number of craters, as expected, increases with the increase in the mass of erodent for all impact angles and this number decreases with the increase of the impact angle. In addition, the counted number of craters is larger than the calculated number of particles at any stage for all impact angles. This may be explained by the effect of the rebound effect of particles, the irregular shape for these particles, and particle fragmentation. The effect of impact angle based on the impact crater shape can be divided into two regions; the first region for θ ≤ 60 deg and the second region for θ ≥ 75 deg. The shape of the craters is related to the dominant erosion mechanisms of plowing and microcutting in the first region and indentation and lip extrusion in the second region. In the first region, the length of the tracks decreases with the increase of impact angle. The calculated size ranges are from few micrometers to 100 μm for the first region and to 50 μm in the second region. Chipping of the former impact sites by subsequent impact particles plays an important role in developing erosion.

Effect of impact angle and velocity on erosion of API X42 pipeline steel under high abrasive feed rate

The cost of erosion attack to the global oil and gas industry has drawn significant attention amongst researchers in recent years. Erosion is a complex phenomenon and in order to recommend ways to mitigate its effect it is essential to have a full understanding of the tribo-mechanisms involved. In the present study erosion tests were conducted on API X42 steel using aluminum oxide as erodent. The extent of material degradation is a function of the properties of abrasive particle, target material, erodent velocity, abrasive feed rate, attack angle and environment. In this study, erosion tests were carried out under high mean abrasive feed rate of 160gmin−1. Particle velocities and attack angles employed were as follows: 36ms−1, 47ms−1, 56ms−1 and 81ms−1 at 30°, 45°, 60° and 90°, respectively. Similar to erosion at low abrasive feed rate, it is found that erosion rate decreases with increasing impact angle and increases with increasing particle velocity. However, under the present experimental conditions, it is found that the velocity exponent (n) in the erosion rate equation (E=kVn) decreases with increasing abrasive particle angle of incidence. Contrary to common understanding for low particle feed rate tests, this finding suggests that the “n” value is mechanism dependent. Several mechanisms are found to be responsible for the behavior of API X42 steel under the experimental conditions used in this work. Heavy plastic deformation and fracture, ploughing and metal cutting are identified as operative mechanisms during erosion of API X42 pipeline steel.

Numerical simulation of pipeline deformation caused by rockfall impact.

Rockfall impact is one of the fatal hazards in pipeline transportation of oil and gas. The deformation of oil and gas pipeline caused by rockfall impact was investigated using the finite element method in this paper. Pipeline deformations under radial impact, longitudinal inclined impact, transverse inclined impact, and lateral eccentric impact of spherical and cube rockfalls were discussed, respectively. The effects of impact angle and eccentricity on the plastic strain of pipeline were analyzed. The results show that the crater depth on pipeline caused by spherical rockfall impact is deeper than by cube rockfall impact with the same volume. In the inclined impact condition, the maximum plastic strain of crater caused by spherical rockfall impact appears when incidence angle α is 45°. The pipeline is prone to rupture under the cube rockfall impact when α is small. The plastic strain distribution of impact crater is more uneven with the increasing of impact angle. In the eccentric impact condition, plastic strain zone of pipeline decreases with the increasing of eccentricity k.

Effect of Feed Rate and Impact Angle on the Erosive Wear of High Velocity Oxy-fuel Sprayed Coating Under High Temperature Conditions

In the present investigation erosive wear behavior of EWAC 1006 Co-base alloy deposited by high velocity oxy-fuel (HVOF) spraying process was investigated. The microstructure, porosity and hardness of the coating was evaluated. The effect of impact angles of 30°, 60° and 90° and erodent feed rate of 1, 3, 5 g/min on the erosive wear were evaluated. All erosive wear tests were conducted at high temperature (450°C) against erodent velocity of 40 m/s. The erosive wear was found to decrease with the increase in impact angle of the erodent and increase with the increase in erodent feed rate. The erosive wear of the coating was 3-4 times lower than the substrate. Analysis of the scanning electron microscope images revealed cutting and lip formation as the material removal mechanisms in these coatings under erosive wear conditions used in this investigation.

Effect of Impact Angle on Slurry Erosion Behavior and Mechanisms of Carburized AISI 5117 Steel

The paper reports the influence of carburizing on the slurry erosion behavior of AISI 5117 steel using a whirling-arm rig. The microstructure and hardness profile of the surface layer of carburized steel were investigated. For characterizing the slurry damage process and for better understanding of material removal at different angles, scanning electron microscope (SEM) images at different locations on eroded surface using stepwise erosion combined with relocation SEM were presented. The study is also focused on studying the erosion wear resistance properties of AISI 5117 steel after carburizing at different impact angles. The tests were carried out with particle concentration of 1 wt. %, and the impact velocity of slurry stream was 15 m/s. Silica sand has a nominal size range of 250 – 355 μm was used as an erodent. The results showed that, carburizing process of steel increased the erosion resistance and hardness compared with untreated material for all impact angles. The erosion resistance of AISI 5117 steel increases by 75%, 61%, 33%, 10% at an impact angle of 30 deg, 45 deg, 60 deg, and 90 deg, respectively, as result of carburizing, i.e., the effectiveness of carburizing was the highest at low impact angles. Treated and untreated specimens behaved as ductile material, and the maximum mass loss appeared at impact angle of 45 deg. Plough grooves and cutting lips appeared for acute impact angle, but the material extrusions were for normal impact angles. The erosion traces were wider and deeper for untreated specimens comparing by the shallower and superficial ones for the carburized specimens. Chipping of the former impact sites by subsequent impact particles plays an important role in developing erosion.