scholarly journals Experimental Investigation of Bow Slamming on a Ship: The Effect of Weight and Impact Angle

Kapal ◽  
2021 ◽  
Vol 18 (1) ◽  
pp. 51-57
Author(s):  
Suandar Baso ◽  
Andi Nadia Himaya ◽  
Faizal Arya Samman ◽  
Andi Dian Eka Anggriani ◽  
Rosmani Rosmani
Keyword(s):  
Peak Pressure ◽  
Pressure Coefficient ◽  
Impact Angle ◽  
Impact Pressure ◽  
Time Duration ◽  
Bottom Part ◽  
Ship Model ◽  
Bow Flare ◽  
Impact Angles ◽  
The Impact

The impact pressure induced by slamming can imply physical damage on a ship. The high probability of the slamming impact is on the bow part in the actual sea state. In this present study, the slamming induced pressure on the bow flare of a ship have been investigated through the experiment. The experiment was schemed by the dropping test based on free-falling body in the wave tank, wherein the bow of the ship model was inclined in several impact angles 0° to 30° to the free-water surface. To measure slamming impact pressure acting on the bow flare, the piezoelectric sensors S1, S2, S3, S4 were attached to the bow section and installed on a computer. As the obtained results, the impact pressure on bow flare occurred in a short time duration caused by slamming. The discrepancy of the peak impact pressure between ship model weight of 2.42 kg and 7.29 kg for the impact angle 0° is 70.36% S1, 69.52% S2, 68.97% S3, and 68.34% S4. For the relative impact angle of 30°, the discrepancy is 67.02% S1, 65.73% S2, 58.51% S3, and 48.21% S4. The tendency of the peak pressure coefficient at the sequenced impact points S1, S2, S3, S4 is similar for all impact angles 0°, 10°, 20°, and 30°. The peak pressure coefficient due to the full load condition is highest in the nearest bottom part, and the peak pressure coefficients due to the lightship condition highest in the nearest bottom part caused by the small impact angle.

Experimental Study of Impact Force of a Low-Speed Droplet Colliding on the Solid Surface at Different Impact Angles

2017 ◽  
Author(s):  
Bin Zhang ◽  
Qian Lv ◽  
Penghua Guo ◽  
Jingyin Li
Keyword(s):  
High Speed ◽  
Impact Force ◽  
Impact Angle ◽  
Force Transducer ◽  
Normal Velocity ◽  
Time Duration ◽  
Low Speed ◽  
Impact Process ◽  
Impact Angles ◽  
The Impact

Erosion problems due to droplet impacts are widely encountered in many fields. This may result in deterioration or even failure of the elements, and should be taken into consideration in the design of machines. The impact force is thought of as an essential factor in material erosion. In this paper, a highly sensitive piezoelectric force transducer was employed to record the impact force of the low-speed droplet colliding on an aluminum plate at different impact angles, in combination with a high-speed camera used to capture the impact process of the droplet. The results showed that the experimental setup can measure the impact force evolution precisely and reliably. The peak of the normal impact force increases with the normal velocity quadratically, while the impulse increases with the normal velocity linearly. In addition, a smaller impact angle would lead to longer time duration of the impact force. The high-speed images show that the initial impact patterns of the droplet have similar behavior in the initial impact process, with regardless of vertical or oblique impacts.

Erosion-Abrasion Behavior of Eutectic Al-Mn Alloy Matrix Composites Reinforced with Al2O3 Particulates

2010 ◽  
Vol 152-153 ◽  
pp. 1054-1057
Author(s):  
Bing Liu ◽  
Xin Mei Li ◽  
Xiang Liu ◽  
Chun Yao Wang
Keyword(s):  
Solid Solution ◽  
Shear Stress ◽  
Impact Angle ◽  
Matrix Composites ◽  
Alloy Matrix ◽  
Abrasion Test ◽  
Wear Rates ◽  
Impact Angles ◽  
The Impact ◽  
Worn Surface

Effects of different impact angles such as 45°and 90°on the erosion-abrasion properties of eutectic Al-Mn alloy and its composites reinforced with Al2O3 particulates were studied by rotating erosion-abrasion test, and the microstructure and the worn surfaces were analyzed. The results show that the as-cast Al-Mn alloy is composed of aluminium-manganese solid solution, MnAl6 and Al11Mn4 phase, while the δ-Al2O3 particles are included in the composites besides the aforementioned microstructures. With elongating the erosion time, the wear rates of the Al-Mn alloy and its composites increase at the impact angle of 90°, whereas they firstly increase and then decrease , and there is a maximum at 45°. The distortion wear caused by the normal stress is dominant at 90°, which lead to the erosion pits on the worn surface. However, the cutting wear by the shear stress is predominant at 45°, which result in the ploughs.

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

2014 ◽  
Vol 136 (2) ◽  
Author(s):  
Y. M. Abd-Elrhman ◽  
A. Abouel-Kasem ◽  
S. M. Ahmed ◽  
K. M. Emara
Keyword(s):  
Rebound Effect ◽  
Impact Angle ◽  
Silica Sand ◽  
Slurry Erosion ◽  
Nominal Size ◽  
Erosion Mechanisms ◽  
Impact Angles ◽  
The Impact ◽  
Calculated Number ◽  
Number Of Particles

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.

Crashworthiness Simulation Analysis of Light Sport Aircraft Fuselage Structure

2011 ◽  
Vol 199-200 ◽  
pp. 48-53 ◽  
Author(s):  
Pu Woei Chen ◽  
Shu Han Chang ◽  
Yu Yang Hsieh ◽  
Tai Sing Sun
Keyword(s):  
Simulation Analysis ◽  
Impact Angle ◽  
General Aviation ◽  
Aviation Industry ◽  
Aircraft Fuselage ◽  
Passenger Safety ◽  
Engine Mount ◽  
Distance Travel ◽  
Impact Angles ◽  
The Impact

In recent years, light sport aircraft, which not only serve the purpose of personal recreation but also act as a means of transportation for medium and short distance travel, have rapidly gained popularity in the general aviation industry worldwide. The FAA established regulations for this new category of airplanes in 2004. However, the crashworthiness requirements for this type of airplane have not been clearly specified. This study used the finite element method to investigate the effect of the impact angle and speed of the LSA fuselage structure on passenger safety during a crash event. We used sink speed defined by NASA AGATE, ASTM and FAR as parameters. The passenger compartment reducing rate defined by MIL-STD-1290A was used for a safety boundary condition. The results show that the maximum cockpit reducing rate of the airplane impact angle is 30o. When the impact angle increases, owing to the engine mount and fire wall’s reinforced structure, this type of airplane can sustain a greater vertical drop speed. When the impact angle is about 80°~90°, the maximum impact speed the fuselage that can be sustained is 33 m/s. This work also completed a simulation of safe and unsafe ranges for light sport aircraft at various impact angles and vertical drop speeds during impact.

scholarly journals Impact and Ricochet of a High Speed Projectile from a Plate

2021 ◽  
Vol 71 (6) ◽  
pp. 737-747
Author(s):  
Hussein Bassindowa ◽  
Bakhtier Farouk ◽  
Steven B. Segletes
Keyword(s):  
Titanium Alloy ◽  
High Speed ◽  
Computational Study ◽  
Incident Angle ◽  
Finite Thickness ◽  
Impact Angle ◽  
Projectile Velocity ◽  
Alloy Plate ◽  
Impact Angles ◽  
The Impact

A computational study of a projectile (either 2024 aluminum or TiAl6V4 titanium alloy) impacting a plate (either titanium alloy or aluminum) is presented in this paper. Projectile velocity (ranging from 250 m/s to 1500 m/s) with varying impact angles are considered. The presence of ricochet (if any) is identified over the ranges of the projectile velocity and impact angle considered. For the cases where ricochet is identified, the ricochet angle and velocity are predicted as functions of the incident angle and the incident velocity. The numerical results are compared with an analytical solution of the ricochet problem. The analytical solutions are from a model developed to predict the ballistic ricochet of a projectile (projectile) penetrator. The dynamics and the deformation of an aluminum (or a titanium alloy) projectile impacting on a finite thickness titanium alloy (or aluminum) plate are simulated. The current work is interesting in that it looks in the field of ballistics of different material combinations than are traditionally studied. The present simulations based on detailed material models for the aluminum and the titanium alloy and the impact physics modelling features in the LS-DYNA code provide interesting details regarding the projectile/plate deformations and post-impact projectile shape and geometry. The present results indicate that for no cases (for specified incoming velocities and impact angles considered) can an aluminum projectile penetrate a titanium alloy plate. The ricochet ‘mode predictions ‘obtained from the present simulations agree well with the ricochet ‘mode predictions’ given in an analytical model.

scholarly journals Neck Moment Characterization of Restrained Child Occupant at Realistic Nontest Standard Higher Impact Speed of 32.2 km/h

2014 ◽  
Vol 2014 ◽  
pp. 1-8
Author(s):  
S. Shasthri ◽  
V. Kausalyah ◽  
Qasim H. Shah ◽  
Kassim A. Abdullah ◽  
Moumen M. Idres ◽  
...  
Keyword(s):  
Interactive Effect ◽  
Impact Angle ◽  
Side Impact ◽  
Impact Speed ◽  
Child Restraint ◽  
Child Restraint System ◽  
Impact Angles ◽  
Child Occupant ◽  
The Impact

The effects of bullet vehicle crash impact angle, child restraint system design, and restraint harness slack at side impact speed of 32.2 km/h (20 mph) on moments sustained at the neck by a three-year-old child are investigated. Mathematical models are built using the response surface method based on simulation results whereby good fitness is achieved. The singular and cross interactive effect of each predictor on the neck moment are analyzed. The number of significant parameters affecting the neck moment is shown to be the largest for wide impact angles (ϕ≥60°) and the impact angle parameter is largely revealed to be the most sensitive. An ideal safe range for low neck moment has been established to be within ϕ angles 45° and 65°. It is further shown that the nature of all parameters effect on the neck moment is highly dependent on the impact angle range.

Impact Pressure Evaluation of Water Jet Peening on Typical Concave Surfaces: Theoretical and Finite Element Analysis

2021 ◽  
Vol 143 (3) ◽  
Author(s):  
Shusen Zhao ◽  
Zhanshu He ◽  
Yanmin Li
Keyword(s):  
Finite Element ◽  
Peak Pressure ◽  
Water Jet ◽  
Impact Pressure ◽  
Concave Surface ◽  
Opening Angle ◽  
Initial Contact ◽  
Groove Surface ◽  
Metal Parts ◽  
The Impact

Abstract Water jet peening (WJP), a surface modification technique, can use the impact pressure induced by shock waves to introduce compressive residual stress in the surface of metal parts, thereby improving the fatigue life of metal parts, especially has broad application prospects in strengthening the concave surface area of metal parts. The impact pressure of the concave surface is different compared with the flat surface due to the effects of geometrical factors on the shock wave released. In this work, a mathematical model for calculating the peak pressure in the initial contact area of the concave surface is developed, and the effects of geometric factors (opening angle of V surface α and spherical radius R) and WJP parameters (jet velocity v and jet diameter d) on the peak pressure are analyzed by using finite element simulation models of WJP on concave V-shaped surface, concave spherical surface, V-groove surface, spherical groove surface, and spherical groove surface established with the coupled Eulerian–Lagrangian (CEL) algorithm of abaqus. A mechanism of impact pressure evaluation of the concave surface is developed to explain the peak pressure results obtained from finite element models. The results show that the peak pressure is mainly determined by α and v, while d does not affect the peak pressure for a concave V-shaped or V-groove surface. The peak pressure is mainly determined by R, v, and d for a concave spherical or spherical groove surface.

Erosion and its Effect on a Water-Cooled Turbine

1978 ◽  
Author(s):  
Max Freedman
Keyword(s):  
Impact Velocity ◽  
Gas Turbines ◽  
Mass Loss Rate ◽  
Impact Angle ◽  
Aluminum Specimen ◽  
High Impact Velocity ◽  
Short Time ◽  
Impact Angles ◽  
The Impact

Erosion tests were run to obtain data for designing a water-cooled gas turbine collection shroud. All tests utilized a coherent stream of water ejected from a static nozzle against stationary small block specimens. Twenty-one tests were run with aluminum specimens and 16 more tests with other materials. The impact velocity was varied from 165 to 270 m/s (540 to 890 fps). The impact angle was varied from 10 to 90 deg. The mass loss rate results generally show four erosion regions, which are consistent with the literature. A correlation between regions two and four was found. Aluminum specimen erosion rate was found to be unexpectedly high with impact angles of 10 deg and moderate-to-high impact velocity. No report of previous liquid erosion work at impact angles less than 30 deg was found; since it is expected that water-cooled gas turbines will operate at impact angles of about 15 deg, erosion in this low impact angle region should be studied. If the correlation between erosion regions two and four can be quantized, then very short-time tests could be used to predict long-term erosion at minimal cost.

Evaluating Impact Properties of Cement Clinker at Different Angle for Impact Indentation

2011 ◽  
Vol 492 ◽  
pp. 43-46
Author(s):  
Xiu Fang Wang ◽  
Yi Wang Bao ◽  
Yan Qiu ◽  
Xiao Gen Liu ◽  
Yuan Tian
Keyword(s):  
Impact Velocity ◽  
Impact Force ◽  
Surface Damage ◽  
Impact Angle ◽  
Cement Clinker ◽  
Damage Degree ◽  
Indentation Tests ◽  
Impact Angles ◽  
The Impact ◽  
Peak Impact Force

Spherical impact indentation tests with different impact angles (90°, 60°, 45°, and 30°) was carried out to understand the effect of impact angles on damage degree of cement clinker. A linear rail which can adjust angle to alter impact velocity was used to guide the slipping impact head to impact the sample. The different steel wedge was used to change the impact angle. It is found that the area of damage surface for cement clinker is most serious the peak impact force for surface damage decreases but the contact indentation becomes longer with decreasing impact angle when the impact angle is 45°. Under almost the same impact velocity, the smaller the impact angle, the higher the impulse, the longer contact time, and the peak impact force of 45° is maximum.

Analysis of Bloodstains Patterns at Sharp Impact Angles

2016 ◽  
Author(s):  
Mohammad Moshfeghi ◽  
Iman Rahimipetroudi ◽  
Nahmkeon Hur
Keyword(s):  
Crime Scene ◽  
Impact Angle ◽  
Equivalent Diameter ◽  
Glycerol Solution ◽  
Fluid Viscosity ◽  
Bloodstain Pattern ◽  
Droplet Sizes ◽  
Impact Angles ◽  
The Impact ◽  
Inclined Surface

Bloodstain pattern analysis is of tremendous value for the investigation of the evidence at the crime scene. Analyzing the bloodstain patterns provides an appropriate method for retracing the origin of blood droplets and also reconstruction of the crime scene. The patterns of the bloodstains on the floors and walls are determined by the impact conditions of blood drops such as droplet sizes, impact angles and velocities. The objective of this work is to study the bloodstain patterns on an inclined surface, in order to categorize the bloodstain shapes. The experiments have been carried out using a 38% glycerol solution at room temperature between 16° C∼21° C. The experiments have been done for three different droplet diameters, five different velocities and four different surface inclinations. The blood-mimicking fluid viscosity and density have been measured at the same temperature range with the experiments. The results have been investigated in terms of bloodstain shape and patterns and three different categories have been determined. In addition, a new mathematical formula has been derived based on the equivalent diameter of the bloodstains, which relates the bloodstain dimensions to the droplet Reynolds and Weber numbers. It has been shown that the proposed formula fits more accurately with the experimental results for high impact angle cases as compared to the classical formula.

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