Miscellaneous Studies in Hard-Hammer Percussion Flaking: The Effects of Oblique Impact

1975 ◽  
Vol 40 (2Part1) ◽  
pp. 203-207 ◽  
Author(s):  
John D. Speth
Keyword(s):  
Impact Angle ◽  
Oblique Impact ◽  
Steel Balls ◽  
Vertical Impact

Steel balls were dropped on to massive glass prisms at an impact angle of 45° in order to determine the effects of oblique impact on several attributes of flake size and flake shape. The results indicate that a flake produced by oblique impact is shorter, but not significantly thinner (except in the immediate area of the cone), than a flake of comparable platform thickness produced by vertical impact.

scholarly journals Abrasive jet micro-machining of metals

2021 ◽  
Author(s):  
Sayeed Ally
Keyword(s):  
Normal Incidence ◽  
Impact Angle ◽  
Oblique Impact ◽  
Micro Machining ◽  
Surface Evolution ◽  
Abrasive Particles ◽  
Micro Features ◽  
Semi Empirical ◽  
First Time ◽  
Good Agreement

Abrasive jet micro-machining is a process that utilizes small abrasive particles entrained in a gas stream to erode material, creating micro-features such as channels and holes. Erosion experiments were carried out on aluminum 6061-T6, Ti-6A1-4V alloy, and 316L stainless steel using 50 μm A1₂O₃ abrasive powder launched at an average speed of 106 m/s. The dependence of erosion rate on impact angle was measured and fitted to a semi-empirical model. The erosion data was used in an analytical model to predict the surface evolution of unmasked channels machined with the abrasive jet at normal and oblique incidence, and masked channels at normal incidence. The predictions of the model were in good agreement with the measured profiles for unmasked channels at normal and oblique impact, and masked channels in at normal incidence up to an aspect ratio (channel depth/width) of 1.25. For the first time, it has been demonstrated that the surface evolution of features machined in metals can be predicted.

Evaluation of Local Damage to Reinforced Concrete Panels Subjected to Oblique Impact of Rigid and Soft Missiles

2018 ◽  
Author(s):  
Akemi Nishida ◽  
Minoru Nagai ◽  
Haruji Tsubota ◽  
Yinsheng Li
Keyword(s):  
Reinforced Concrete ◽  
Simulation Method ◽  
Impact Angle ◽  
Oblique Impact ◽  
Local Damage ◽  
Empirical Formulas ◽  
Rc Structures ◽  
Impact Tests ◽  
Oblique Impacts ◽  
The Impact

Many empirical formulas have been proposed for evaluating local damage to reinforced concrete (RC) structures caused by impacts of rigid missiles. Most of these formulas have been derived based on impact tests normal to the target structures. Up to now, few impact tests oblique to the target structures have been carried out. This study has been conducted with the purpose of proposing a new formula for evaluating the local damage caused by oblique impacts based on previous experimental and simulation results. In this paper, the results of simulation analyses for evaluating the local damage to a RC panel subjected to normal and oblique impacts by rigid and soft missiles, by using the simulation method that was validated using the results of previous impact experiments. Based on the results of these simulation analyses, the effects of the rigidity of the missile as well as the impact angle on the local damage to the target structures are clarified.

scholarly journals A lattice Boltzmann simulation of oblique impact of a single rain droplet on super-hydrophobic surface with randomly distributed rough structures

2020 ◽  
Vol 15 (3) ◽  
pp. 443-449
Author(s):  
Zhang Shusheng ◽  
Lu Hao ◽  
Zhang Li-Zhi ◽  
Riffat Saffa ◽  
Ure Zafer ◽  
...  
Keyword(s):  
Lattice Boltzmann ◽  
Contact Time ◽  
Hydrophobic Surface ◽  
Impact Angle ◽  
Oblique Impact ◽  
Building Structures ◽  
Pinning Effect ◽  
Lattice Boltzmann Simulation ◽  
Boltzmann Method ◽  
The Impact

Abstract In this paper, oblique impact of a single rain droplet on super-hydrophobic surface with randomly distributed rough structures was investigated by lattice Boltzmann method. The effects of the impact angle of the droplet as well as the skewness and kurtosis of rough surface on the bouncing ability of the droplet were in this paper. It was found that the oblique impact can effectively reduce the contact time in the process of droplet bouncing off, because the energy consumption caused by the pinning effect is reduced. Moreover, the contact time most possibly reaches the shortest when the impact angle is 45°. Decreasing the skewness and keeping the kurtosis around 4.0 can enhance the bouncing ability during the droplet oblique impact on randomly distributed rough surfaces. The results are useful for the design of building structures.

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

Wear ◽  
2015 ◽  
Vol 332-333 ◽  
pp. 1028-1034 ◽  
Author(s):  
Maha Messaadi ◽  
Guillaume Kermouche ◽  
Philippe Kapsa
Keyword(s):  
Experimental Analysis ◽  
Impact Angle ◽  
Oblique Impact ◽  
Impact Effect

A study on the frontal oblique collision-induced derailment mechanism in subway vehicles

2019 ◽  
Vol 234 (6) ◽  
pp. 584-595
Author(s):  
Shuguang Yao ◽  
Huifen Zhu ◽  
Mingyang Liu ◽  
Zhixiang Li ◽  
Ping Xu ◽  
...  
Keyword(s):  
Lateral Displacement ◽  
Element Model ◽  
Vertical Displacement ◽  
Rigid Wall ◽  
Impact Angle ◽  
Oblique Impact ◽  
Oblique Collision ◽  
Impact Speed ◽  
Vertical Displacements ◽  
The Impact

Oblique collisions can more easily lead to train derailment and cause heavy casualties. In this paper, a fine finite-element model of a subway head vehicle–rigid wall frontal oblique collision was established and validated by a single wheelset derailment simulation. Furthermore, the derailment mechanisms and patterns under an oblique impact angle of 6.34°–40° and at an impact speed of 8–40 km/h were studied via simulation. The results indicated that three types of derailment, such as roll-over derailment, climb/roll-over derailment and wheel-lift derailment, have occurred. When the impact speed was set to 25 km/h, a climb/roll-over derailment occurred under the impact angle of greater than 40°; a roll-over derailment occurred under the impact angle of 20°–40°; and the vehicle would not derail when the impact angle was less than 15°. When the impact angle was 6.34°, the vehicle was in danger of wheel-lift derailment with the largest wheel vertical displacement of 26.83 mm and lateral displacement of 12.52 mm under the impact speed of 40 km/h, but it was safe with the largest displacement of no more than 18 mm and lateral displacement of 8.39 mm if the impact speed was less than 40 km/h. It is shown that the derailment patterns are more sensitive to the impact angle. Therefore, both the lateral and vertical displacements should be considered when studying the oblique collision-induced derailment mechanisms and patterns.

scholarly journals Abrasive jet micro-machining of metals

2021 ◽  
Author(s):  
Sayeed Ally
Keyword(s):  
Normal Incidence ◽  
Impact Angle ◽  
Oblique Impact ◽  
Micro Machining ◽  
Surface Evolution ◽  
Abrasive Particles ◽  
Micro Features ◽  
Semi Empirical ◽  
First Time ◽  
Good Agreement

Abrasive jet micro-machining is a process that utilizes small abrasive particles entrained in a gas stream to erode material, creating micro-features such as channels and holes. Erosion experiments were carried out on aluminum 6061-T6, Ti-6A1-4V alloy, and 316L stainless steel using 50 μm A1₂O₃ abrasive powder launched at an average speed of 106 m/s. The dependence of erosion rate on impact angle was measured and fitted to a semi-empirical model. The erosion data was used in an analytical model to predict the surface evolution of unmasked channels machined with the abrasive jet at normal and oblique incidence, and masked channels at normal incidence. The predictions of the model were in good agreement with the measured profiles for unmasked channels at normal and oblique impact, and masked channels in at normal incidence up to an aspect ratio (channel depth/width) of 1.25. For the first time, it has been demonstrated that the surface evolution of features machined in metals can be predicted.

Shock Pressure in Oblique Impact—A Theoretical Analysis

1974 ◽  
Vol 41 (1) ◽  
pp. 124-130 ◽  
Author(s):  
C. A˚ke Persson
Keyword(s):  
Shock Wave ◽  
Pressure Rise ◽  
Impact Angle ◽  
Oblique Impact ◽  
Shock Pressure ◽  
Elastic Media ◽  
Linear Elastic ◽  
Wave Velocities ◽  
Impact Angles ◽  
The Impact

The variation of shock pressure with the angle between the colliding surfaces in an oblique impact between two plane plates is analyzed theoretically. The analysis is carried out for small impact angles and the plate materials are assumed to behave like fluids (Case 1) and linear elastic media (Case 2). In the latter case the two extreme assumptions concerning the friction at the interface, no friction and no sliding, are treated. The results show that the shock pressure increases quadratically with the impact angle (except for some of the no sliding cases, where decreasing pressure can occur) and that the pressure rise is strongly dependent upon the ratio between the impact velocity and the shock wave velocities for the plate materials.

scholarly journals Experimental study on mechanical property and stone-chip resistance of automotive coatings

2021 ◽  
Author(s):  
Yang Liu ◽  
Chenqi Zou ◽  
Mengyan Zang ◽  
Shunhua Chen
Keyword(s):  
High Speed ◽  
Paint Film ◽  
Tensile Load ◽  
Single Layer ◽  
Impact Angle ◽  
Oblique Impact ◽  
Strong Nonlinearity ◽  
Automotive Coatings ◽  
Impact Tester ◽  
Paint Films

Abstract The damage of automotive coatings caused by stone impact is a problem that has attracted great attention from automotive companies and users. In this work, experiments were conducted to investigate the dynamic tensile properties and stone-chip resistance of automotive coatings. Four kinds of paint films and three typical coatings (single-layer electrocoat coating, single-layer primer coating, and multilayered coating) were used. Under dynamic tensile load using split Hopkinson tension bar (SHTB), the engineering stress-strain curves of the paint films at medium and high strain rates (from 50 to 600 s-1) were obtained. Results indicated that the mechanical properties of the paint films exhibited strong nonlinearity and strain-rate correlation. A modified anti-impact tester was used to complete repeatable single impact tests. The effects of some key parameters, i.e., impact velocity, impact angle, and paint film thickness, on the stone-chip resistance of coatings were systematically investigated. The influence of contact type under high-speed impact conditions was investigated as well. The surface morphologies of the coatings after impact were examined by scanning electron microscopy (SEM), and the failure mechanism of the coatings under normal/oblique impact was discussed. In all experiments, the paint films showed brittle fracture behavior.

Fractal Characterization of Slurry Eroded Surfaces at Different Impact Angles

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
Abouel-Kasem ◽  
M. A. Al-Bukhaiti ◽  
K. M. Emara ◽  
S. M. Ahmed
Keyword(s):  
Erosion Rate ◽  
Impact Angle ◽  
Oblique Impact ◽  
Slurry Erosion ◽  
Normal Impact ◽  
Power Spectral ◽  
Impact Angles ◽  
The Impact ◽  
The Relationship

In the present work, the topographical images of slurry erosion surfaces at different impact angles were quantified using fractal analysis. The study showed that the variation of fractal value of slope of linearized power spectral density with the impact angle is largely similar to the relationship between the erosion rate and the impact angle. Both the fractal value and erosion rate were maximum at 45 deg and 90 deg for ductile and brittle materials, respectively. It was found also that the variation of fractal values versus the impact angle has a general trend that does not depend on magnification factor. The fractal features to the eroded surfaces along different directions showed high directionality at oblique impact angle and were symmetrical at normal impact.

Effects of Impact Angle on Cone Crack Formation in Impact-Loaded Soda-Lime Glass

2004 ◽  
Vol 261-263 ◽  
pp. 319-324 ◽  
Author(s):  
Moon Saeng Kim ◽  
Hyung Seop Shin ◽  
Hyeon Chul Lee ◽  
Ho Jong Kim
Keyword(s):  
Crack Formation ◽  
Soda Lime ◽  
Impact Angle ◽  
Soda Lime Glass ◽  
Ball Impact ◽  
Cone Crack ◽  
Cone Formation ◽  
Punching Process ◽  
Steel Balls ◽  
The Impact

In order to investigate the possibility of punching process of brittle material by ball impact, effects of impact angle on cone crack formation in impact-loaded soda-lime glass were evaluated experimentally. Evaluated were also contact area between specimen and sealing, and the optimal condition for cone crack formation in glass plates by impact with small steel balls. It has been found that lateral and radial cracks gradually developed asymmetrically. However, the perfect cone cracks were found to develop almost symmetrically. As the impact angle increased, the growth rate of cone cracks decreased. Regardless of the impact angle, the PMMA sealing was more effective for perfect cone formation than Aluminum and Polyurethane sealing. Thus, the application for industrial technology for hole (or nozzle) punching process of the brittle materials is expected to be feasible, based upon proper selection of sealing materials.

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