scholarly journals FRAGMENTATION OF COLLIDING DISCS

1996 ◽  
Vol 07 (06) ◽  
pp. 837-855 ◽  
Author(s):  
FERENC KUN ◽  
HANS J. HERRMANN
Keyword(s):  
Mass Distribution ◽  
Initial Velocity ◽  
Cell Model ◽  
Low Velocity Impact ◽  
Anomalous Scaling ◽  
Low Velocity ◽  
Velocity Impact ◽  
Brittle Solids ◽  
A Cell ◽  
The Impact

We study the phenomena associated with the low-velocity impact of two solid discs of equal size using a cell model of brittle solids. The fragment ejection exhibits a jet-like structure the direction of which depends on the impact parameter. We obtain the velocity and the mass distribution of the debris. Varying the radius and the initial velocity of the colliding particles, the velocity components of the fragments show anomalous scaling. The mass distribution follows a power law in the region of intermediate masses.

Experimental investigation of low velocity impact on textile cellular composite with different energy construction

2018 ◽  
Vol 48 (6) ◽  
pp. 1009-1023 ◽  
Author(s):  
Xiaozhou Gong ◽  
Pengying Pei ◽  
Yu Hu ◽  
Xiaogang Chen
Keyword(s):  
Cell Size ◽  
Impact Energy ◽  
Initial Velocity ◽  
Low Velocity Impact ◽  
Wall Material ◽  
Low Velocity ◽  
Velocity Impact ◽  
Cellular Composite ◽  
Big Cell ◽  
The Impact

Cellular composite, with an array of regular hexagonal cells in the cross section, is a type of textile composites having the advantage of being light weight and energy absorbent over the solid composite materials. However, when it is under the same energy level of low velocity impact with different tup mass and velocity, its behavior is yet unknown. In the experiment, four groups of samples, with twelve geometrical variants have been systematically created for the impact testing. The impact test is running in two categories with one type of low velocity impact with initial velocity of 5.5 m/s by the tup mass of 0.55 kg, and another testing under the similar impact energy but with a lower initial velocity around 2.0 m/s with heavier tup mass of 4.52 kg. The impact energies in the above cases are very similar about 8.5 J, which indicates that the impact energy is the same while the energy construction is different. After the test, it is found that composite with medium cell size has more stable mechanical performances under various exposed impact conditions. It is also concluded that composites with big cell size are much easier to be destroyed under heavier impact tup, therefore, under condition of more critical loading force, it is necessary to find a way to enhance the big cell sized composites’ wall material in order to strengthen their structure performances. The results of this work provide a reference for the researchers who are kneeing to investigate the impact mechanism of textile cellular composites.

Response and failure modes of biaxial warp-knitted flexible composite subject to low-velocity impact

2021 ◽  
pp. 152808372110154
Author(s):  
Ziyu Zhao ◽  
Tianming Liu ◽  
Pibo Ma
Keyword(s):  
Impact Energy ◽  
Linear Density ◽  
Failure Modes ◽  
Impact Response ◽  
Low Velocity Impact ◽  
Minor Effect ◽  
Low Velocity ◽  
Velocity Impact ◽  
Flexible Composites ◽  
The Impact

In this paper, biaxial warp-knitted fabrics were produced with different high tenacity polyester linear density and inserted yarns density. The low-velocity impact property of flexible composites made of polyurethane as matrix and biaxial warp-knitted fabric as reinforcement has been investigated. The effect of impactor shape and initial impact energy on the impact response of flexible composite is tested. The results show that the initial impact energy have minor effect on the impact response of the biaxial warp-knitted flexible composites. The impact resistance of flexible composite specimen increases with the increase of high tenacity polyester linear density and inserted yarns density. The damage morphology of flexible composite materials is completely different under different impactor shapes. The findings have theoretical and practical significance for the applications of biaxial warp-knitted flexible composite.

Coda Waves for Health Monitoring of Composites Under Low-Velocity Impact

2021 ◽  
Author(s):  
Subal Sharma ◽  
Vinay Dayal
Keyword(s):  
Ultrasonic Waves ◽  
Coda Waves ◽  
Low Velocity Impact ◽  
Coda Wave ◽  
Low Velocity ◽  
Fibrous Composite Material ◽  
Velocity Impact ◽  
Isotropic Composite ◽  
The Impact ◽  
Impact Damages

Abstract Coda waves have been shown to be sensitive to lab-controlled defects such as very small holes in fibrous composite material. In the real world, damages are subtler and more irregular. The main objective of this work is to investigate coda wave capability to detect low-velocity impact damages. The emphasis is to detect the presence of barely visible impact damages using ultrasonic waves. Detection of incipient damage state is important as it will grow over the life of the structure. Differential features, previously used in similar work, have been utilized to detect realistic impact damages on carbon fiber composites. Quasi-isotropic composite laminates were subjected to low-velocity impact energy ranging from 2J to 4.5J. Two differential features reported could be used detect the presence of damage. It is also observed that ply orientation can be a deterministic factor for indicating damages. The size and shape of the impact damage has been characterized using ultrasonic C-scans. Results indicate that coda waves can be used for the detection of damage due to low-velocity impact.

Low Velocity and Compression-After-Impact Response of Pin-Reinforced Sandwich Composites

1999 ◽  
Author(s):  
Uday K. Vaidya ◽  
Mohan V. Kamath ◽  
Mahesh V. Hosur ◽  
Anwarul Haque ◽  
Shaik Jeelani
Keyword(s):  
Impact Testing ◽  
Low Velocity Impact ◽  
Sandwich Composites ◽  
Low Velocity ◽  
Static Compression ◽  
Velocity Impact ◽  
Transverse Stiffness ◽  
Impact Studies ◽  
Compression After Impact ◽  
The Impact

Abstract In the current work, sandwich composite structures with innovative constructions referred to as Z-pins, or truss core pins are investigated, in conjunction with traditional honeycomb and foam core sandwich constructions, such that they exhibit enhanced transverse stiffness, high damage resistance and furthermore, damage tolerance to impact. While the investigations pertaining to low velocity impact have appeared recently in Vaidya et al. 1999, the current paper deals with compression-after-impact studies conducted to evaluate the residual properties of sandwich composites “with” and “without” reinforced foam cores. The resulting sandwich composites have been investigated for their low velocity (< 5 m/sec) impact loading response using instrumented impact testing at energy levels ranging from 5 J to 50 J impact energy. The transverse stiffness of the cores and their composites has also been evaluated through static compression studies. Compression-after-impact studies were then performed on the sandwich composites with traditional and pin-reinforcement cores. Supporting vibration studies have been conducted to assess the changes in stiffness of the samples as a result of the impact damage. The focus of this paper is on the compression-after-impact (CAI) response and vibration studies with accompanying discussion pertaining to the low velocity impact.

Effect of SiO2 Nanoparticles on the Mechanical and Low Velocity Impact Properties of Epoxy/Glass Composites

2016 ◽  
Vol 838 ◽  
pp. 29-35
Author(s):  
Michał Landowski ◽  
Krystyna Imielińska
Keyword(s):  
Flexural Strength ◽  
Energy Absorption ◽  
Impact Energy ◽  
Epoxy Matrix ◽  
Low Velocity Impact ◽  
Low Velocity ◽  
Nanoparticle Suspension ◽  
Impact Properties ◽  
Velocity Impact ◽  
The Impact

Flexural strength and low velocity impact properties were investigated in terms of possibile improvements due to epoxy matrix modification by SiO2 nanoparticles (1%, 2%, 3%, 5%, 7%wt.) in glass/epoxy laminates formed using hand lay-up method. The matrix resin was Hexion L285 (DGEBA) with Nanopox A410 - SiO2 (20 nm) nanoparticle suspension in the base epoxy resin (DGEBA) supplied by Evonic. Modification of epoxy matrix by variable concentrations of nanoSiO2 does not offer significant improvements in the flexural strength σg, Young’s modulus E and interlaminar shear strength for 1% 3% and 5% nanoSiO2 and for 7% a slight drop (up to ca. 15-20%) was found. Low energy (1J) impact resistance of nanocomposites represented by peak load in dynamic impact characteristics was not changed for nanocompoosites compared to the unmodified material. However at higher impact energy (3J) nanoparticles appear to slightly improve the impact energy absorption for 3% and 5%. The absence or minor improvements in the mechanical behaviour of nanocomposites is due to the failure mechanisms associated with hand layup fabrication technique: (i.e. rapid crack propagation across the extensive resin pockets and numerous pores and voids) which dominate the nanoparticle-dependent crack energy absorption mechanisms (microvoids formation and deformation).

Low Velocity Impact on Fiber Reinforced Geocomposites

2016 ◽  
Vol 827 ◽  
pp. 145-148 ◽  
Author(s):  
Sneha Samal ◽  
David Reichmann ◽  
Iva Petrikova ◽  
Bohdana Marvalova
Keyword(s):  
Impact Damage ◽  
Acoustic Vibration ◽  
Low Velocity Impact ◽  
Low Velocity ◽  
Velocity Impact ◽  
Impact Behaviour ◽  
Reinforced Composite ◽  
Before And After ◽  
Two Parameters ◽  
The Impact

Low velocity impact strength of the fabric reinforced geocomposite has investigated in this article. Various fabrics such as carbon and E-glass were considered for reinforcement in geopolymer matrix. The primary two parameters such as low velocity, impact damage modes are explained on the E-glass and carbon based fabric geocomposite. The onset mode of damage to failure mode is examined through C-scan analysis. The quality of the composite is observed using c-scan with acoustic vibration mode of sensor before and after impact test. Then the effect of fabric and matrix on the impact behaviour is discussed. Residual strength of the composite is measured to determine post impact behaviour. It has been observed that resistance properties of E-glass reinforced composite is better than carbon fabric reinforced composite.

scholarly journals Experimental and numerical analysis of high and low velocity impacts against neat and shear thickening fluid (STF) impregnated weave fabrics

2018 ◽  
Vol 183 ◽  
pp. 01044
Author(s):  
Djalel Eddine Tria ◽  
Larbi Hemmouche ◽  
Abdelhadi Allal ◽  
Abdelkader Benouali
Keyword(s):  
High Velocity ◽  
Shear Thickening ◽  
Force Sensor ◽  
Low Velocity Impact ◽  
Dynamic Force ◽  
Low Velocity ◽  
Shear Thickening Fluid ◽  
Velocity Impact ◽  
Pull Out ◽  
The Impact

This investigation aims to study the efficiency of STF impregnated plain-weave fabric made of Kevlar under high and low velocity impact conditions. The shear thickening fluid (STF) was prepared by ultrasound irradiation of silica nanoparticles (diameter ≈30 nm) dispersed in liquid polyethylene glycol polymer. STF impregnation effect was determined from single yarn pull-out test and penetration at low velocity using drop weight machine equipped with hemi-spherical penetrator and dynamic force sensor. Force-displacement curves of neat and impregnated Kevlar were analysed and compared. Also, the STF impregnation effect on Kevlar multilayers was analysed from high velocity impact tests using 9mm FMJ bullet at 390 m/s. After impact, Back face deformation (BFD) of neat and impregnated Kevlar layers were measured and compared. Results showed that STF impregnated fabrics have better energy absorption and penetration resistance as compared to neat fabrics without affecting the fabric flexibility. When relative yarn translations are restricted (e.g. at very high levels of friction), windowing and yarn pull-out cannot occur, and the fibres engaged with the projectile fail in tension that leads to fabric penetration. Microscopy of these fabrics after testing have shown pitting and damage to the Kevlar filaments caused by the hard silica particles used in the STF. Mesoscopic 3D Finite Element models were developed using explicit LS-DYNA hydrocode to account for STF impregnation by employing the experimental results of yarn pull-out tests, low and high velocity impacts. It was found that friction between fibers and yarns increase the dissipation of energy upon impact by restricting fiber mobility, increasing the energy required for relative yarn translations and transferring the impact energy to a larger number of fibers.

RESIDUAL STRENGTH OF SANDWICH STRUCTURE SUBJECTED TO LOW VELOCITY IMPACT

2006 ◽  
Vol 20 (25n27) ◽  
pp. 4384-4389 ◽  
Author(s):  
KI-WEON KANG ◽  
JUNG-KYU KIM ◽  
SEONG-KYUN CHEONG ◽  
HEUNG-SEOB KIM
Keyword(s):  
Residual Strength ◽  
Sandwich Structure ◽  
Strength Reduction ◽  
Low Velocity Impact ◽  
Low Velocity ◽  
Reduction Behavior ◽  
Static Tests ◽  
Velocity Impact ◽  
Impact Tester ◽  
The Impact

The goals are to identify the strength reduction behavior and its statistical properties of sandwich structure subjected to low velocity impact. For these, the impact tests were performed using the impact tester and the damages are inspected by SAM. And then, subsequent static tests are conducted under flexural loading for the impacted structures. The strength reduction behavior is evaluated via the residual strength prediction model. Also, a statistical model is developed to identify the fluctuation of residual strength. The model well describes the distribution of residual strength.

Low-Velocity Impact on a Functionally Graded Circular Thin Plate

2006 ◽  
Author(s):  
Pantele Chelu ◽  
Liviu Librescu
Keyword(s):  
Plate Theory ◽  
Equation System ◽  
Functionally Graded ◽  
Low Velocity Impact ◽  
Thin Plates ◽  
Low Velocity ◽  
Alternative Analysis ◽  
Velocity Impact ◽  
Graded Material ◽  
The Impact

In this paper, an alternative analysis strategy based on a Wavelet-Galerkin scheme specially tailored to solve impact problems of functionally graded orthotropic thin plates subjected to low-velocity impact is presented. The plate considered to be circular, is assumed to be clamped on its lateral edge and has internal supports of rigid, elastic and viscoelastic types. The material properties of the plate are represented in the form of exponential functions of the thickness coordinate. A rigid spherical indenter impacts the plate. The study is based on the classical lamination plate theory (CLT). An advanced contact law of the Hertzian type is adopted. A nonlinear Volterra integral equation system is obtained in the following unknown functions: the impact force and the dynamic reaction forces at the rigid, elastic and viscoelastic internal point supports. Numerical simulations displaying the contact force, the transversal displacement and the penetration depth are graphically presented, and pertinent conclusions regarding the implications of incorporation of graded material systems are outlined.

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