Effect Of Impact Angle Research Articles

Effect of impact angle on hot corrosion resistance of abrasive water jet peened Ti-6Al-4V alloy

The effect of peening angle (10° to 40°) on NaCl induced hot corrosion behavior of Ti-6Al-4V alloy was evaluated at 750 °C for 100 h. Peening at higher impact angles progressively increases the surface roughness, number of sub-grains, magnitude of compressive residual stresses and hardness of the alloy. During hot corrosion, the surfaces of Ti-6Al-4Al, irrespective of the peened condition, develops oxide scales that contain oxides of Ti, Al and V. Hot corrosion rate, measured in terms of rate of mass gain and the rate constant, Kp, was highest for the unpeened alloy but decreased for surfaces subjected to AWJ peening. Surfaces peened at increasing impact angles have smaller mass gain rate and the one peened at the impact angle of 30° exhibited the lowest corrosion rate and a lowest Kp of ~0.08 mg2/cm4/h. The surface peened at 40° is, however, not as corrosion resistant. The mechanism of corrosion was discussed in the context of corrosion products formed and the opposing influences of initial roughness and compressive residual stresses. While higher roughness promotes hot corrosion by facilitating sites for corrosive attack, higher compressive residual stresses retard the diffusion of corrosive species into the Ti-6Al-4V surface. Based on these discussions, the optimum impact angle for AWJ peening for imparting maximum hot corrosion resistance on Ti-6Al-4V was determined to be ~30°.

Impact resistance and energy absorption characteristics of nickel-based alloy ring at elevated temperatures

To evaluate the high-temperature containment capability of a turbine casing, the impact resistance of half-ring specimens and full circular casings made of GH4169 nickel-based alloy was investigated. Ballistic impact tests were first conducted on GH4169 half-ring specimens using blade-shaped projectiles of DZ125 material fired from a single-stage gas gun. Meanwhile, explicit finite element simulations of the half-ring impact tests were performed with LS-DYNA. Comparing experimental and simulation results validated the accuracy of the model and revealed the effects of impact angle and ambient temperature. Then the process of a turbine casing containing a blade at 500 °C was simulated using the validated FE model. The results showed that the impact angle and the ambient temperature significantly affect the impact resistance of GH4169 half-ring specimen. Furthermore, the interaction mechanism between the turbine blade and casing differs across the three stages of the containment process.

Tungsten wall cratering under high-velocity dust impacts: Influence of impact angle and temperature

The integrity of plasma-facing components (PFCs) in fusion reactors is severely tested by high-velocity dust collisions, which occur during explosive events such as runaway electron terminations. These events can expel dust particles at velocities of 0.5 – 1 km/s in current fusion devices and potentially several km/s in advanced reactors like ITER and DEMO, leading to significant material erosion and damage. Given the limitations of existing models, which effectively address only low-velocity impacts, there is a critical need for improved modeling of high-velocity dust-wall interactions. This study utilizes molecular dynamics (MD) simulations to explore the effects of impact angle and target temperature on the interactions between tungsten (W) dust particles and W walls under extreme velocities ranging from 2.5 to 4.5 km/s. Our research focuses on analyzing the morphology of impact craters, and characteristics of ejecta across a range of impact angles (0° to 75°) and with dislocation density for temperatures (300 to 3000 K). Our study reveals that the angle of impact and temperature almost exclusively determine the shape of the crater and the distribution of ejecta, highlighting the critical role of these factors in the dynamics of dust-wall interactions. Comparison with the experimental data obtained from W-on-W impact tests shows a strong correlation with our theoretical predictions.

First direct observations of interplanetary shock impact angle effects on actual geomagnetically induced currents: The case of the Finnish natural gas pipeline system

The impact of interplanetary (IP) shocks on the Earth’s magnetosphere can greatly disturb the geomagnetic field and electric currents in the magnetosphere-ionosphere system. At high latitudes, the current systems most affected by the shocks are the auroral electrojet currents. These currents then generate ground geomagnetically induced currents that couple with and are highly detrimental to ground artificial conductors including power transmission lines, oil/gas pipelines, railways, and submarine cables. Recent research has shown that the shock impact angle, the angle the shock normal vector performs with the Sun-Earth line, plays a major role in controlling the subsequent geomagnetic activity. More specifically, due to more symmetric magnetospheric compressions, nearly frontal shocks are usually more geoeffective than highly inclined shocks. In this study, we utilize a subset (332 events) of a shock list with more than 600 events to investigate, for the first time, shock impact angle effects on the subsequent GICs right after shock impact (compression effects) and several minutes after shock impact (substorm-like effects). We use GIC recordings from the Finnish natural gas pipeline performed near the Mäntsälä compression station in southern Finland. We find that GIC peaks (> 5 A) occurring after shock impacts are mostly caused by nearly frontal shocks and occur in the post-noon/dusk magnetic local time sector. These GIC peaks are presumably triggered by partial ring current intensifications in the dusk sector. On the other hand, more intense GIC peaks (> 20 A) generally occur several minutes after shock impacts and are located around the magnetic midnight terminator. These GIC peaks are most likely caused by intense energetic particle injections from the magnetotail which frequently occur during substorms. The results of this work are relevant to studies aiming at predicting GICs following solar wind driving under different levels of asymmetric solar wind forcing.

Effects of impact angles and shapes on CAI strength of composite honeycomb structure

The Compression After Impact (CAI) strength can enhance safety and reliability in engineering applications, improve simulation and prediction capabilities. It is also an important indicator for assessing the damage tolerance capacity of composite structures. The CAI strength is directly influenced by low-velocity impact, which holds significant scientific research implications for evaluating structural safety, optimising design and enhancing material properties. Analysing different impact shapes and angles provide a closer representation of real-world engineering scenarios, rendering results more reliable and valuable. The subject is a CFRP panel with Nomex honeycomb sandwich structure, where both the skin and core are composed of composite materials. Low-velocity impact and compression after impact tests were conducted to establish an integrated and refined finite element model for the CFRP panel with Nomex honeycomb structure. The model’s validity was confirmed by comparing with test results. Various impact shapes and angles were investigated using the established model to examine their influence on the CAI strength of the composite honeycomb sandwich structure. The following conclusions were drawn: (1) Sharper impactors result in lower CAI strength and higher compressive failure displacement. (2) The CAI strength, normalised CAI strength, and failure displacement of the structure increase with the impact angles. Among the tested angles, the 30° impact angle induced the least damage, exhibiting the highest CAI strength, normalised CAI strength, and failure displacement. However, as the angle increases, energy losses between the impactor and specimen increase, impact energy decrease. Consequently, the structural indicators decrease compared to the 30° impact angle.

Role of Impact Angle on Equatorial Electrojet (EEJ) Response to Interplanetary (IP) Shocks

AbstractInterplanetary (IP) shocks are one of the dominant solar wind structures that can significantly impact the Geospace when impinge on the Earth's magnetosphere. IP shocks severely distort the magnetosphere and induce dramatic changes in the magnetospheric currents, often leading to large disturbances in the geomagnetic field. Sudden enhancements in the solar wind dynamic pressure (PDyn) during IP shocks cause enhanced high‐latitude convection electric fields which penetrate promptly to equatorial latitudes. In response, the equatorial electrojet (EEJ) current exhibits sharp changes of magnitudes primarily controlled by the change in PDyn and the local time. In this paper, we further investigated the influence of shock impact angle on the EEJ response to a large number (306) of IP shocks that occurred during 2001–2021. The results consistently show that the EEJ exhibits a heightened response to the shocks that head‐on impact the magnetosphere (frontal shocks) than those with inclined impact (inclined shocks). The greater EEJ response during the frontal shocks could be due to a more intensified high‐latitude convection electric field resulting from the symmetric compression of the magnetosphere. Finally, an existing empirical relation involving PDyn and local time is improved by including the effects of impact angle, which can quantitatively better predict the EEJ response to IP shocks.

Theoretical modeling of concrete friction-impact deterioration using water-borne sand abrasion experiment

To explore the influence of impact angle on concrete abrasion deterioration under water-borne sand, a theoretical model for friction-impact deterioration was developed. This model innovatively proposes the inhibition effect of the normal impact action on the tangential friction mass loss and the facilitation effect of the tangential friction action on the normal impact mass loss to rationally explain the effect of impact angle on concrete mass loss. Simultaneously, a water-borne sand accelerated abrasion experiment was conducted to initiate a comprehensive discussion on surface abrasion deterioration indicators, including mass loss, number of holes, aperture, hole area, and hole volume. In addition, the concrete abrasion mass loss rate was evaluated based on the friction-impact deterioration model combined with experimental data. Applying this model facilitates a reliable prediction of concrete's mass loss caused by abrasion. Consequently, this allows for a more accurate assurance of the safety of concrete structures exposed to abrasive conditions throughout their operational life. The results show that the mass loss per unit area, maximum aperture, hole area ratio, and hole volume exhibit a trend of first decreasing, then increasing and finally decreasing with the increase of impact angle. Under 15°, 60°, and 90°, 70 % of the mass loss per unit area of the concrete specimens occurred within the first 6 d of abrasion. When the angles were 30° and 45°, 50 % of the mass loss per unit area of the concrete specimens occurred in the 9–12 d abrasion. It has been revealed that 69° results in the most severe abrasion mass loss. The abrasion deterioration process of concrete can be divided into three primary stages, including surface mortar abrasion, prime aggregate-mortar abrasion, and continuous aggregate-mortar abrasion. Additionally, the friction-impact theoretical model was employed to simulate the abrasion of both single and multiple pier columns, and the simulations provided insights into the non-uniform mass loss rate distribution around the pier columns.

Research on the solid particle erosion wear of pipe steel for hydraulic fracturing based on experiments and numerical simulations

Erosion wear is a common failure mode in the oil and gas industry. In the hydraulic fracturing, the fracturing pipes are not only in high-pressure working environment, but also suffer from the impact of the high-speed solid particles in the fracturing fluid. Beneath such complex conditions, the vulnerable components of the pipe system are prone to perforation or even burst accidents, which has become one of the most serious risks at the fracturing site. Unfortunately, it is not yet fully understood the erosion mechanism of pipe steel for hydraulic fracturing. Therefore, this article provides a detailed analysis of the erosion behavior of fracturing pipes under complex working conditions based on experiments and numerical simulations. Firstly, we conducted erosion experiments on AISI 4135 steel for fracturing pipes to investigate the erosion characteristics of the material. The effects of impact angle, flow velocity and applied stress on erosion wear were comprehensively considered. Then a particle impact dynamic model of erosion wear was developed based on the experimental parameters, and the evolution process of particle erosion under different impact angles, impact velocities and applied stress was analyzed. By combining the erosion characteristics, the micro-structure of the eroded area, and the micro-mechanics of erosion damage, the erosion mechanism of pipe steel under fracturing conditions was studied in detail for the first time. Under high-pressure operating conditions, it was demonstrated through experiments and numerical simulations that the size of the micro-defects in the eroded area increased as the applied stress increased, resulting in more severe erosion wear of fracturing pipes.

High-velocity oblique impact experiments on ice and snow spheres: Implications for the collisional evolution of icy planetesimals at different thermal evolution stages

In order to determine the effect of impact angle on the impact strength of icy planetesimals, we conducted a range of oblique impact experiments for spherical ice and snow targets simulating icy planetesimals at different thermal evolution stages. The ice targets had no porosity and the snow targets had a porosity of 0.5. A polycarbonate or glass sphere impacted the ice targets at 744–1747 m s−1 and the snow targets at 938–5085 m s−1 over a range of impact angles from grazing to head-on collisions. All experiments were conducted using a two-stage light gas gun and a target chamber set in a cold room of −15 °C at Kobe University, Japan. The impact strength, which is a specific energy, Q, when the largest fragment mass is a half of the original target mass, for the ice and snow targets in a head-on collision was determined to be 12 and 520 J kg−1, respectively, whereas it was found that the impact strength depended on the impact velocity. Thus, the normalized largest fragment mass, ml/Mt, could well scale with the velocity dependent Q, that is, Qviγ (where ml and Mt are the masses of largest fragment and target, respectively, and vi is the impact velocity). At high Q, ml/Mt increased drastically with the decrease of impact angle when the impact angle was smaller than a critical angle, θc, and θc~30° for the ice targets and θc~45° for the snow targets. At small Q, ml/Mt continued to increase as the impact angle became smaller for both types of targets. The ml/Mt for oblique impacts had a good correlation with the effective specific energy, Qeff=Qsin2θ, where θ is the impact angle, and the effective impact strength was determined to be 16 J kg−1 and 499 J kg−1 for the ice and snow targets, irrespective of the impact angle. Furthermore, the scaling parameter, Πs_eff, which was proposed by Housen and Holsapple (1990) but includes Qeff instead of Q, multiplied by 1−ϕλ, where ϕ is the porosity, showed even better correlation with ml/Mt, and all ml/Mt data of ice and snow targets could be merged, irrespective of impact velocity and ϕ. Based on our experimental results and a theory on the oblique impact of solar system bodies proposed by Shoemaker (1962), we could estimate the degree of disruption (ml/Mt) at any impact energy and any impact angle for icy planetesimals. Our findings demonstrate that the degree of disruption for icy planetesimals that have experienced sufficient thermal evolution was larger than that for those that did not experience significant thermal evolution.

Effect of Impact Angle and Speed, and Weight Abrasive Concentration on AISI 1015 and 304 Steel Exposed to Erosive Wear

Effect of Impact Angle and Speed, and Weight Abrasive Concentration on AISI 1015 and 304 Steel Exposed to Erosive Wear

Effect of impingement angle and impact velocity on slurry erosive wear behaviour of particulate reinforced aluminium composites

Effect of impingement angle and impact velocity on slurry erosive wear behaviour of particulate reinforced aluminium composites

A multiscale computation study on bruise susceptibility of blueberries from mechanical impact

Impact bruising is a prevalent form of mechanical damage that occurs in blueberries during harvesting and postharvest handling processes. The accurate quantification of bruising remains a challenging task, primarily due to the limitations of available technologies. To address this issue, herein, the data-enabled computational method was employed to evaluate the bruise susceptibility of blueberries under various free drop scenarios. A multiscale computational model, comprising the skin, flesh, and seeds, was constructed based on the anatomical structures of blueberries. The mechanical properties were obtained through compression tests, and free drop experiments were conducted to validate the computational model. A total of 120 cases were simulated, considering various drop heights, impact angles, and contact surface materials. Based on simulation results, empirical models to predict bruise susceptibility were developed specifically for each contact surface material using the response surface methods. The results revealed that mechanical behavior of blueberries subjected to compressive loading was adequately described using a linear elastic-plastic model, with Young’s modulus, tangent modulus, and yielding strain being 0.339 MPa, 0.166 MPa, and 0.185, respectively. The equivalent plastic strain (PEEQ) metric from simulations effectively captured bruising distribution in drop impacts with a bruising threshold value set at 0.1. Bruise susceptibility was influenced by the modulus ratios between the contact surface material and blueberry, and exhibited a linear positive relationship with drop heights. In addition, the effect of impact angle was contingent on the drop height. At lower drop heights, greater bruising occurred at vertical impact angles. As the drop height increased, the blueberries became more susceptible to bruising at the horizontal impact angles. The specific transition in drop height varied among different contact surface materials. These results demonstrate the capability of the multiscale computational model to simulate drop scenarios and assess the bruise susceptibility of blueberries. The theoretical insights provided by this study offer valuable guidance for optimizing fresh-market blueberry mechanical harvesting machine design and postharvest handling processes for longer shelf-life.

Facial Fracture Injury Criteria from Night Vision Goggle Impact.

INTRODUCTION: Military personnel extensively use night vision goggles (NVGs) in contemporary scenarios. Since NVGs may induce or increase injuries from falls or vehicular accidents, biomechanical risk assessments would aid design goal or mitigation strategy development.METHODS: This study assesses injury risks from NVG impact on cadaver heads using impactors modeled on the PVS-14 NVG. Impacts to the zygoma and maxilla were performed at 20° or 40° angles. Risks of facial fracture, neurotrauma, and neck injury were assessed. Acoustic sensors and accelerometers assessed time of fracture and provided input variables for injury risk functions. Injuries were assessed using the Abbreviated Injury Scale (AIS); injury severity was assessed using the Rhee and Donat scales. Risk functions were developed for the input variables using censored survival analyses.RESULTS: The effects of impact angle and bone geometry on injury characteristics were determined with loading area, axial force, energy attenuation, and stress at fracture. Probabilities of facial fracture were quantified through survival analysis and injury risk functions. These risk functions determined a 50% risk of facial bone fracture at 1148 N (axial force) at a 20° maxillary impact, 588 N at a 40° maxillary impact, and 677 N at a 20° zygomatic impact. A cumulative distribution function indicates 769 N corresponds to 50% risk of fracture overall.DISCUSSION: Results found smaller impact areas on the maxilla are correlated with higher angles of impact increasing risk of facial fracture, neck injuries are unlikely to occur before fracture or neurotrauma, and a potential trade-off mechanism between fracture and brain injury.Davis MB, Pang DY, Herring IP, Bass CR. Facial fracture injury criteria from night vision goggle impact. Aerosp Med Hum Perform. 2023; 94(11):827-834.

Effect of Impact Angles and Temperatures on the Solid Particle Erosion Behavior of HVOF Sprayed WC-Co/NiCr/Mo and Cr3C2-CoNiCrAlY Coatings

Effect of Impact Angles and Temperatures on the Solid Particle Erosion Behavior of HVOF Sprayed WC-Co/NiCr/Mo and Cr3C2-CoNiCrAlY Coatings

DEM-FEM coupling analysis of shot′s energy distribution and target′s residual stress of pneumatic shot peening

Pneumatic shot peening is a widely used surface strengthening method. During the peening process, shots often collide with each other, resulting in large energy loss and small compressive residual stress. In order to achieve the optimum compressive residual stress with as little energy loss as possible, firstly the collision mechanism of shots and the forming and coupling mechanism of the target’s residual stress are revealed, and then pneumatic shot peening is simulated by using DEM-FEM coupling model. Then, the effects of impact angle θ, initial shot velocity v 0, shot diameter d p, and mass flow rate r m on the percentage η of shots with different ratios of the impact velocity to initial shot velocity v m/v 0, the energy loss (EL), the energy transferred from shots to the target (ET), the residual energy (ER) and the compressive residual stress (RS) are investigated. The results show that as many random shots successively impact the target, the RS field induced by each shot couples with some adjacent RS fields induced by other shots, so that disperse RS fields are gradually transformed into a continuous RS layer with the compressive RS in the surface and the tensile RS in the subsurface. With the increase of θ and r m and with the decrease of v 0 and d p, the collision probability of shots increases, so EL also increases and η of shots with a large v m/v 0 decreases. While, ET increases with the increase of v 0 and d p, decreases with the increase of r m, and first increases and then decreases with the increase of θ. ET does not entirely determine but greatly affects the compressive RS field. So, the surface compressive RS and the maximum compressive RS first increase and then decrease with the increase of θ and r m, while the two parameters increase with the increase of v 0 and d p. The optimum parameters of shots are θ = 75°, v 0 = 60 m s−1, d p = 0.25 mm and r m = 2 kg min−1, in which ET reaches 45%, the surface compressive RS of S11 and S33 reach 512 MPa and 510 MPa respectively, and the maximum compressive RS of S11 and S33 reach 665 MPa and 746 MPa respectively.

Dynamic response and failure analysis for urban bridges under far-field blast loads

Compared to near/mid-field explosions, the far-field blast generates blast waves with long duration and propagation distance, which will cause distinctly different damage effects. The dynamic response and failure mechanism of urban bridges under far-field blast loads are numerically investigated in this work. To address the excessive model scale caused by the direct simulation and remapping methods, approximate far-field blast waves are input into the air domain through the Autodyn subroutine in the present far-field blast simulations. The reliability of the loading method and the fluid-structure interaction simulation scheme adopted here is then demonstrated by published experimental data. Based on an urban bridge prototype, the refined numerical model of the bridge is established. Eventually, the failure process and damage modes of the bridge under far-field explosions are analyzed, while the effects of impact angles and load parameters are explored. The results imply that (i) the response of the bridge under far-field explosions is global, while the typical features in the response process are the pier tilt and superstructure uplift; (ii) the damage modes of the bridge include crush and twist of piers, damage to shear keys, cracking of bent caps, and movement of the superstructure; (iii) the decrease of impact angle exacerbates the pier displacement and reduces the superstructure uplift; (iv) for peak overpressure, decay parameter and positive phase duration, the bridge structural response is most sensitive to peak overpressure.

Crashworthiness of double-gradient hierarchical hexagonal tubes under multiple loads

Hierarchical design and gradient design have been shown to improve the crashworthiness of structures. However, fewer studies combine the two. Therefore, this study combines the two to design a novel double-gradient hierarchical hexagonal tube (DGHHT) based on a hexagonal tube (HT). According to the different axial gradients, they are divided into DGHHT-1 and DGHHT-2. The crashworthiness under multiple loads was studied by finite element simulation. Firstly, the reliability of the finite element model is validated by experimental results. Secondly, compared with single-gradient hierarchical hexagonal tubes (SGHHT), DGHHT have better resistance to global bending under multiple loads. When studying mass effects, it was found that both HT and DGHHT had increased peak force and SEA. When HT is designed as DGHHT-2, specific energy absorption (SEA) can be increased by up to 82.74%. Studying the effects of impact angle found that DGHHT-2 has better resistance to global bending than HT as the angle increases. Studying the effect of DGHHT-2 axial gradient distribution found that reasonable distribution of its axial gradient can further improve its ability to resist global bending. Finally, compared with the structures proposed in other studies, DGHHT-2 also has better resistance to global bending at an impact angle of 30°. The double-gradient hierarchical design in this study can provide new design ideas for crashworthiness design.

Ice impact response and energy dissipation characteristics of PVC foam core sandwich plates: Experimental and numerical study

In this paper, the dynamic responses and energy dissipation characteristics of polyvinyl chloride (PVC) foam core sandwich plates under ice impact are investigated. The ice impact tests of PVC foam core sandwich plates were conducted by employing the horizontal impact experimental apparatus. The finite element simulations were conducted to analyze the dynamic response of PVC foam core sandwich plates based on soil and concrete material model for ice impactor. It was demonstrated that numerical results were in good agreement with experimental results. The deformation modes of the top facesheets were coupling of local indentation with global bending deformation, while the deformation modes of bottom facesheets were overall bending deformation. The permanent deformation of face sheets show that the impact resistance of sandwich plate is better than that of equivalent weight hull plate (EWHP). In addition, based on the actual navigation environment of ship, the effect of impact angle and ice floe shape on dynamic response and energy dissipation are analyzed.

Effect of Impact Angle on the Impact Mechanical Properties of Bionic Foamed Silicone Rubber Sandwich Structure.

In this paper, a red-eared slider turtle is used as the prototype for the bionic design of the foamed silicone rubber sandwich structure. The effect of impact angle on the performance of the foamed silicone rubber sandwich structure against low-velocity impact is studied by the finite element method. The numerical model uses the intrinsic structure model of foamed silicone rubber with porosity and the three-dimensional Hashin fiberboard damage model. The validity of the model was verified after experimental comparison. Based on the finite element simulation of different impact angles and velocities, the relationship between impact velocity and residual velocity, as well as the penetration threshold at various impact angles are obtained, and the change law of impact resistance of foamed silicone rubber sandwich structure with impact angle and velocity, as well as the damage pattern of sandwich structure at different impact angles and velocities are given. The results can provide a basis for the impact resistance design of the bionic foamed silicone rubber sandwich structure. The results show that, at a certain impact speed, the smaller the impact angle, the longer the path of the falling hammer along the plane of the sandwich structure, the lighter the damage to the sandwich structure and the greater the absorbed energy, so that avoiding the impact from the frontal side of the sandwich structure can effectively reduce the damage of the sandwich structure. When the impact angle is greater than 75°, the difference in impact resistance performance is only 2.9% compared with 90°, and the impact angle has less influence on the impact resistance performance at this time.

Effect of impingement angle and impact velocity on slurry erosive wear behaviour of particulate reinforced aluminium composites

Effect of impingement angle and impact velocity on slurry erosive wear behaviour of particulate reinforced aluminium composites