Penetration Fracture Characteristics of CFRP Curved Shells According to Oblique Impact

2006 ◽  
Vol 306-308 ◽  
pp. 291-296 ◽  
Author(s):  
In Young Yang ◽  
Young Jea Cho ◽  
Kwang Hee Im ◽  
Cheon Seok Cha ◽  
Young Nam Kim
Keyword(s):  
Slope Angle ◽  
High Strength ◽  
Structural Materials ◽  
Oblique Impact ◽  
Steel Ball ◽  
Curvature Radius ◽  
Transverse Impact ◽  
Reinforced Plastics ◽  
Impact Surface ◽  
The Impact

CFRP (Carbon Fiber Reinforced Plastics) of the advanced composite materials as structural materials for vehicles, has a wide application in light weighs structural materials of airplanes, ships and automobiles because of high strength and stiffness. However, there is a design variable to be considered in practical application of the laminate composite material, that is, this material is vulnerable to transverse impact. This paper aims at evaluating the effects of curvature and oblique impact on the penetration characteristics of composite laminate shells. They are stacked to [02/902]S, [03/903]S and [02/903/0]S, [0/902/0]S and their interlaminar number two and four. Those specimens were prepared to varied curvature radius (R=100, 150, 200mm and ∞). They are cured by heating to the appropriate hardening temperature (130oC) by means of a heater at the vacuum bag of the autoclave. Test specimens were prepared with dimensions 100mm×140mm. When the specimen is subjected to transverse impact by a steel ball, the velocity of the steel ball was measured both before and after impact by determining the time for it to pass two ballistic-screen sensors located a known distance apart. In general, the critical penetration energy increased as the curvature increased, interface decreased and slope angle on the impact surface increased.

The effect of surface roughness on oblique bicycle helmet impact tests

2020 ◽  
Vol 234 (4) ◽  
pp. 320-327
Author(s):  
Philip G Petersen ◽  
Lloyd V Smith ◽  
Derek Nevins
Keyword(s):  
Surface Roughness ◽  
Oblique Impact ◽  
Road Surface ◽  
Rotational Acceleration ◽  
Impact Surface ◽  
Impact Tests ◽  
Side Impacts ◽  
Road Surfaces ◽  
The Impact ◽  
Abrasive Paper

The friction between a helmet and impact surface affects the accelerations imparted to the head. The roughness of the impact surface is, therefore, a consideration when developing oblique impact standards. An 80-grit abrasive paper is commonly used in oblique impact tests to simulate a road surface, but has not been validated for bicycle impacts and may not accurately represent real road surfaces. In the following study, a helmeted NOCSAE headform with a Hybrid III neck was dropped onto a 45° anvil at 6.5 m/s using a twin wire guided drop tower. Helmeted drops were performed in two orientations (frontal and side) on road surfaces, roughened steel surfaces, 80-grit abrasive paper and a low friction surface. For each impact, measures of linear and rotational acceleration were obtained. These metrics were compared across impact orientations and surfaces to assess the influence of surface roughness on headform impact response. Frontal impacts were less sensitive to the impact surface roughness than side impacts across metrics. Among metrics, rotational acceleration showed the largest effect due to surface roughness. Compared to the road surface, peak rotational acceleration from impacts on the 80-grit surface were 6.5% less and 48% greater for frontal and side impacts, respectively. Based on consideration of the peak and cumulative impact measures, steel impact surfaces appear to better simulate road impact than the commonly used 80-grit abrasive paper.

Analysis of Postimpact Plastic Indentation Profiles

2015 ◽  
Vol 809-810 ◽  
pp. 223-228 ◽  
Author(s):  
Stelian Alaci ◽  
Florina Carmen Ciornei ◽  
Constantin Filote ◽  
Ionuţ Cristian Românu
Keyword(s):  
Mild Steel ◽  
Coordinate System ◽  
Laser Scanner ◽  
Vertical Axis ◽  
Angular Speed ◽  
Steel Ball ◽  
Curvature Radius ◽  
Impact Point ◽  
Plastic Indentation ◽  
The Impact

The paper presents the analysis of plastic indentations resulting after the impact between a steel ball and a disc made of mild steel, rotating about a vertical axis. The imprints are analysed using a laser scanner, the profiles of the mark, in normal and tangent section about the impact point radius, being relevant. It is shown that the use of parabolas is sufficient to approximate the profiles of the imprint. The profiles from the two sections are interpolated and then brought for comparison into the same coordinate system. Finally, the curvature radii of the profiles from the two sections are found and the remark that increasing the angular speed of the disc presents opposite effects to the curvature radius in the two sections.

A STUDY ON DAMAGE BEHAVIOR OF GLASS BY OBLIQUE IMPACT OF STEEL BALL

2006 ◽  
Vol 20 (25n27) ◽  
pp. 4291-4296 ◽  
Author(s):  
CHANG-MIN SUH ◽  
DONG-KYUN KIM ◽  
MOON-HWAN LEE
Keyword(s):  
Finite Element ◽  
Crack Length ◽  
Impact Test ◽  
Oblique Impact ◽  
Steel Ball ◽  
Crack Growth Behavior ◽  
Soda Lime Glass ◽  
Ball Impact ◽  
Damage Behavior ◽  
The Impact

The damage behavior of soda-lime glass was studied by oblique impact test with a steel ball, and in order to investigate the effect of roughness damage on glass, variable damages and strength degradation of smooth and Al 2 O 3 sand blasted for roughness glass was investigated by the ball impact test. After the test, the crack patterns were investigated using a stereo-microscope. In addition, the finite element method was performed to analyze the stress distribution and variation in the glass impacted obliquely by the steel ball. As a result of the impact test, the crack length of 90° impacted glass was the largest and that of 50° impacted glass was the smallest. In particular, as the impact velocity and diameter of the steel ball increased, the difference in crack length was prominent. The finite element analysis showed the maximum principle stresses distribution in the contact area of glass specimen. The result of analysis was accorded with the crack growth behavior by the oblique impact test.

Study on Impact Characteristics of CFRP Structural Member According to Stacking Conditions

2014 ◽  
Vol 680 ◽  
pp. 254-257
Author(s):  
Ju Ho Choi ◽  
Yong Jun Yang ◽  
Cheon Seok Cha ◽  
In Young Yang
Keyword(s):  
High Strength ◽  
Structural Member ◽  
Reinforced Plastics ◽  
Advanced Composite ◽  
Collapse Characteristics ◽  
Advanced Composite Materials ◽  
Fiber Reinforced Plastics ◽  
Strength And Stiffness ◽  
Impact Characteristics ◽  
The Impact

CFRP (Carbon Fiber Reinforced Plastics) is an anisotropic material which is the most widely adapted lightweight structural member. CFRP of the advanced composite materials as structure materials for vehicles has a widely application in lightweight structural materials of air planes, ships and automobiles because of high strength and stiffness. The CFRP Square members were made of 8ply unidirectional prepreg sheets stacked at different angles and interface numbers. Based on the collapse characteristics of CFRP member, the collapse characteristics and energy absorption capability were analyzed. The impact collapse tests were carried out for each section member. The purpose is to examine experimentally absorption behavior and strength evaluation depending on changes in the stacking configuration when the CFRP Square member s with different stacking configuration is exposed to separate impact velocity.

A Study on Impact Strength of CFRP Using Infrared Thermography

2012 ◽  
Vol 628 ◽  
pp. 390-395 ◽  
Author(s):  
Hee Jae Shin ◽  
Lee Ku Kwac ◽  
Sun Ho Ko ◽  
Tae Hoon Kim ◽  
Hong Gun Kim
Keyword(s):  
Thermal Characteristics ◽  
High Strength ◽  
Reinforced Plastics ◽  
Advanced Composite ◽  
Average Temperature ◽  
Advanced Composite Materials ◽  
Weight Test ◽  
Strength And Stiffness ◽  
Falling Weight ◽  
The Impact

Of the advanced composite materials for aerospace structures such as aircrafts and space devices, the carbon fiber reinforced plastics (CFRP) is applied to many sectors that require lightweight materials for its high strength and stiffness. One of the disadvantages of the CFRP, however, is that it is weak against impact. In this study, impact test specimens were manufactured with five fiber stacking angles (0°/0°, 0°/15°, 0°/30°, 0°/45°, 0°/90°) according to ASTM D7136[15], and a falling weight test was performed to analyze the correlation between their mechanical and thermal characteristics. As a result, the impact energy applied to the five test specimens with different fiber stacking angles was almost constant at 30.63 J - 30.78 J. The absorbed energy increased with the increase in the fiber stacking angle, and decreased after 0°/45°. The average temperature on the fractured surface increased with the increase in the fiber stacking angle in all specimens other than the 0°/0° specimen.

A discussion on deformation of solids by the impact of liquids, and its relation to rain damage in aircraft and missiles, to blade erosion in steam turbines, and to cavitation erosion - Oblique impact of a jet on a plane surface

1966 ◽  
Vol 260 (1110) ◽  
pp. 96-100 ◽  
Keyword(s):  
Plane Surface ◽  
Thin Sheet ◽  
Small Region ◽  
Oblique Impact ◽  
Stagnation Pressure ◽  
Angle Of Incidence ◽  
Steam Turbines ◽  
Lateral Velocity ◽  
Impact Surface ◽  
The Impact

The dynamics of the region where a jet, striking a plane surface obliquely, is transformed into a thin sheet will be discussed. The maximum (stagnation) pressure is the same for all angles of incidence but the area over which the high pressure acts is much reduced as the angle of incidence, 0 , becomes small. The main transformation from a jet to a sheet is due to a pressure of order sin 2 0 x the jet cross section. The pressure is due to the destruction of the component of velocity normal to the impact surface, but since pressure acts equally in all directions it imparts lateral velocity to streams which are not in the plane of symmetry. Each element of the stream can be regarded as passing through a small region where an impulsive body force changes its direction without changing its velocity, and some properties of this impulse will be described. One case will be given where the transformations from a jet to a thin flat sheet can be described completely and the calculated distribution of pressure in the region where it occurs compared with experimental measurements. Though a jet cannot produce a pressure greater than the stagnation pressure as a steady state, it seems theoretically possible to attain a much higher pressure for a short time when a very oblique jet is moved sideways.

Finite Element Analysis of Transverse Impact on a Woven Textile

2004 ◽  
Author(s):  
Yiping Duan ◽  
Michael Keefe ◽  
Travis A. Bogetti ◽  
Brian Powers
Keyword(s):  
Finite Element ◽  
Failure Modes ◽  
High Strength ◽  
Theoretical Work ◽  
Impact Behavior ◽  
Transverse Impact ◽  
Element Analysis ◽  
Distribution Energy ◽  
The Impact ◽  
Woven Textile

High-strength textiles are widely used in soft impact threat shield systems. During the past several decades, a lot of experiments and theoretical work were conducted to understand the transverse impact behavior of textile structures. As a continuation of those efforts, this paper presents finite element modeling of transverse impact of a rigid right circular cylinder into a square patch of plain-woven textile. Two boundary conditions are applied on the woven textile: four edges clamped; two opposite edges clamped and the other two edges left free. Results show that during the initial stage of the impact, there exists an abrupt momentum/energy transfer from the projectile to the local textile in the impact region. The modeling results also show that the textile boundary condition plays an important role in the impact. It significantly affects the textile transient deformation, stress distribution, energy absorption, and failure modes. The textile absorbs energy more quickly when all its four edges are clamped.

scholarly journals Impact resistance of steel materials to ballistic ejecta and shelter development using steel deck plates

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Hiroyuki Yamada ◽  
Kohei Tateyama ◽  
Shino Naruke ◽  
Hisashi Sasaki ◽  
Shinichi Torigata ◽  
...  
Keyword(s):  
Impact Energy ◽  
Impact Test ◽  
Impact Resistance ◽  
Protective Layer ◽  
High Strength ◽  
Steel Plates ◽  
Corrugated Plates ◽  
Shelter Construction ◽  
The Impact ◽  
Ballistic Ejecta

AbstractThe destruction caused by ballistic ejecta from the phreatic eruptions of Mt. Ontake in 2014 and Mt. Kusatsu-Shirane (Mt. Moto-Shirane) in 2018 in Japan, which resulted in numerous casualties, highlighted the need for better evacuation facilities. In response, some mountain huts were reinforced with aramid fabric to convert them into shelters. However, a number of decisions must be made when working to increase the number of shelters, which depend on the location where they are to be built. In this study, we propose a method of using high-strength steel to reinforce wooden buildings for use as shelters. More specifically, assuming that ballistic ejecta has an impact energy of 9 kJ or more, as in previous studies, we developed a method that utilizes SUS304 and SS400 unprocessed steel plates based on existing impact test data. We found that SUS304 is particularly suitable for use as a reinforcing material because it has excellent impact energy absorption characteristics due to its high ductility as well as excellent corrosion resistance. With the aim of increasing the structural strength of steel shelters, we also conducted an impact test on a shelter fabricated from SS400 deck plates (i.e., steel with improved flexural strength provided by work-hardened trapezoidal corrugated plates). The results show that the shelter could withstand impact with an energy of 13.5 kJ (2.66 kg of simulated ballistic ejecta at 101 m/s on impact). In addition, from the result of the impact test using the roof-simulating structure, it was confirmed the impact absorption energy is further increased when artificial pumice as an additional protective layer is installed on this structure. Observations of the shelter after the impact test show that there is still some allowance for deformation caused by projectile impact, which means that the proposed steel shelter holds promise, not only structurally, but also from the aspects of transportation and assembly. Hence, the usefulness of shelters that use steel was shown experimentally. However, shelter construction should be suitable for the target environment.

scholarly journals Effect of W on the Impact-Induced Energy Release Behavior of Al–Ni Energetic Structural Materials

Metals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1217
Author(s):  
Shun Li ◽  
Caimin Huang ◽  
Jin Chen ◽  
Yu Tang ◽  
Shuxin Bai
Keyword(s):  
Energy Release ◽  
Structural Materials ◽  
Damage Effect ◽  
Hot Press ◽  
Reaction Heat ◽  
Metal Metal ◽  
Energetic Structural Materials ◽  
Released Energy ◽  
The Impact ◽  
Hot Press Process

Energetic structural materials (ESMs) are an important class of military materials due to their good structural and energy-releasing characteristics. To improve the damage effect of metal–metal ESMs with good mechanical properties, W was added to the 48Al–52Ni composites, and the effect of W on the impact-induced energy release behaviors was investigated. The results showed that the hot-press process and the addition of W did not change the microstructure and surface state of the constituent particles, leading to a stable onset temperature of the Al–Ni intermetallic reaction in (48Al–52Ni)100-xWx composites. Meanwhile, the decrease in the contact area between Al and Ni in the composites with increased W content resulted in the decrease in reaction heat. During the impact process, the intermetallic reaction of W caused by the Al–Ni intermetallic reaction, as well as the oxidation reaction of Al and Ni caused by the brittle fracture along the weak interface, caused the released energy of (48Al–52Ni)40W60 to reach 2.04 kJ/g.

scholarly journals Toughness Property Control by Nb and Mo Additions in High-Strength Quenched and Tempered Boron Steels

Metals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 95
Author(s):  
Irati Zurutuza ◽  
Nerea Isasti ◽  
Eric Detemple ◽  
Volker Schwinn ◽  
Hardy Mohrbacher ◽  
...  
Keyword(s):  
Solid Solution ◽  
Transition Temperature ◽  
High Strength ◽  
Unit Size ◽  
Tempered Martensite ◽  
Size Refinement ◽  
Direct Quenching ◽  
Property Control ◽  
The Impact ◽  
Impact Transition Temperature

The synergetic effect on hardenability by combining boron with other microalloying elements (such as Nb, Mo and Nb + Mo) is widely known for high-strength medium carbon steels produced by direct quenching and subsequent tempering treatment. The improvement of mechanical properties could be reached through optimization of different mechanisms, such as solid solution hardening, unit size refinement, strain hardening, fine precipitation hardening and the effect of carbon in solid solution. The current study proposes a procedure for evaluating the contribution of different microstructural aspects on Charpy impact toughness. First, the effect that austenite conditioning has on low-temperature transformation unit sizes and microstructural homogeneity was analysed for the different microalloying element combinations. A detailed crystallographic characterization of the tempered martensite was carried out using electron backscattered diffraction (EBSD) in order to quantify the effect of unit size refinement and dislocation density. The impact of heterogeneity and presence of carbides was also evaluated. The existing equations for impact transition temperature (ITT50%) predictions were extended from ferrite-pearlite and bainitic microstructures to tempered martensite microstructures. The results show that microstructural refinement is most beneficial to strength and toughness while unit size heterogeneity has a particularly negative effect on ductile-to-brittle transition behaviour. By properly balancing alloy concept and processing, steel having a yield strength above 900 MPa and low impact transition temperature could be obtained by direct quenching and tempering.

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