SIMPLIFIED ANALYSIS OF LOW VELOCITY IMPACT ACTIONS ON SHALLOW DOMES

2013 ◽  
Vol 05 (02) ◽  
pp. 1350013 ◽  
Author(s):  
YI YANG ◽  
NELSON LAM ◽  
LIHAI ZHANG ◽  
EMAD GAD
Keyword(s):  
Nonlinear Behavior ◽  
Low Velocity Impact ◽  
Elastic Behavior ◽  
Response Behavior ◽  
Lumped Mass ◽  
Low Velocity ◽  
Mass Model ◽  
Simplified Approach ◽  
Lumped Masses ◽  
The Impact

This paper is concerned with a simplified approach of estimating the effects of the impact of a projectile on a circular dome. The procedure to be introduced involves simplifying the impactor (projectile) and the target (the dome) by a two-degree-of-freedom (2DOF) system which is made up of two lumped masses connected by elastic springs. This modeling approach has only been adapted for analyzing the impact response behavior of beams and plates. The original contributions of this paper is the development of equations and charts for estimating the value of the lumped mass and spring stiffness in the 2DOF lumped mass model to emulate the response behavior of circular domes. Linear elastic behavior of the dome is assumed but nonlinear behavior of the impactor has been taken into account. The developed calculation procedure has been validated and illustrated by case studies.

ESTIMATION OF RESPONSE OF PLATE STRUCTURE SUBJECT TO LOW VELOCTIY IMPACT BY A SOLID OBJECT

2012 ◽  
Vol 12 (06) ◽  
pp. 1250053 ◽  
Author(s):  
Y. YANG ◽  
N. T. K. LAM ◽  
L. ZHANG
Keyword(s):  
Low Velocity Impact ◽  
Solid Object ◽  
Response Behavior ◽  
Lumped Mass ◽  
Low Velocity ◽  
Plate Structure ◽  
Novel Method ◽  
Lumped Masses ◽  
The Impact ◽  
Two Degree Of Freedom

This paper introduces the use of a two-degree-of-freedom (2DOF) model which comprises two spring-connected lumped masses for analyzing the response behavior of a plate structure to a low velocity impact of a flying solid object. We propose a novel method for calculating the value of the equivalent lumped mass and that of the spring constant which characterizes the 2DOF model. This is an important contribution given that existing calculation methods that are based on results from modal analysis would only be suitable for modeling the impact actions of wind or blast. Analysis involving the use of a 2DOF model is inexpensive and convenient to operate whilst achieving very good accuracies as demonstrated herein. By contrast, modeling impact response behavior by finite element analyses can be very time consuming and labour intensive because of the need to model in detail the impactor in contact with the target.

Low-velocity impact on cylindrically curved bilayers

2018 ◽  
Vol 232 (4) ◽  
pp. 568-576
Author(s):  
A Bidi ◽  
Gh Liaghat ◽  
Gh Rahimi
Keyword(s):  
Shear Deformation Theory ◽  
Low Velocity Impact ◽  
Fourier Series Expansion ◽  
Balance Model ◽  
Radius Of Curvature ◽  
Hertz Contact ◽  
Low Velocity ◽  
Mass Model ◽  
Velocity Impact ◽  
The Impact

In this study, low-velocity impact response of cylindrically curved bilayer panels is studied. A large number of parameters affect the impact dynamics and many models have been used for solution previously. These models can be classified as energy balance model, spring–mass model, and complete models in which the dynamic behavior of the structure is exactly modeled. In this study, a two degrees of freedom spring–mass model is used to evaluate contact force between the composite panel and impactor. This work uses the modified Hertz contact model which is linearized form of general Hertz contact law. First-order shear deformation theory coupled with Fourier series expansion is used to derive the governing equations of the curved bilayer panel. The effects of panel curvature, impact velocity, and mass of impactor on the panel behavior under low-velocity impact are investigated. The results show that changing the panel radius of curvature will change the impact force, impact duration, and local panel deformation. Finally, analytical solutions have been compared with numerical results.

SIMULATIONS OF RESPONSE TO LOW VELOCITY IMPACT BY SPREADSHEET

2010 ◽  
Vol 10 (03) ◽  
pp. 483-499 ◽  
Author(s):  
N. T. K. LAM ◽  
H. H. TSANG ◽  
E. F. GAD
Keyword(s):  
Approximate Solutions ◽  
Low Velocity Impact ◽  
Elastic Response ◽  
Governing Equations ◽  
Lumped Mass ◽  
Low Velocity ◽  
Computational Tools ◽  
Single Degree Of Freedom ◽  
Dynamic Analyses ◽  
The Impact

A program which can be used to simulate the elastic response of lumped mass single-degree-of-freedom systems to impact actions is introduced in this paper. The underlying governing equations and the implementation of their solutions on a spreadsheet are described. As illustrated in the paper, the program can be extended to obtaining approximate solutions for the inelastic response of a reinforced column to the impact by a vehicle. Solutions obtained from the developed spreadsheet have been compared with those obtained by other means. Few engineers have the skills of undertaking their own sanity checks on analyses involving transient actions including that of the impact of an object. Codes of practices often resort to the use of equivalent static loading for representing transient actions and this may give misleading results. Portable and inexpensive computational tools like the ones presented herein enable engineers to conveniently undertake their own sanity checks on computer output from dynamic analyses.

scholarly journals Modelling of Low-velocity Impacts on Composite Beams in Large Displacement

2021 ◽  
Vol 15 (58) ◽  
pp. 254-271
Author(s):  
Mattia Utzeri ◽  
Marco Sasso ◽  
Gianluca Chiappini ◽  
Stefano Lenci
Keyword(s):  
Analytical Model ◽  
Experimental Test ◽  
High Speed ◽  
Time History ◽  
Free Vibrations ◽  
Large Displacement ◽  
Low Velocity Impact ◽  
Lumped Mass ◽  
Low Velocity ◽  
The Impact

The paper provides an evaluation of the nonlinear dynamic response of a cantilever beam made of composite material subjected to low-velocity impacts. The structure is assumed to respond in a quasi-static manner and modelled by a continuous beam in large displacement with a lumped mass attached. First, an analytical model was developed to study the free vibrations of a beam, taking into account the nonlinearities due to large displacements and inertia. Then, the analytical findings were compared with experimental test data. The vibration of a real composite beam has been acquired through high-speed imaging technique. The displacements of the beam were extracted by digital image analysis; then, the nonlinear parameters of the analytical model were determined by the Fitting Time History technique. The results obtained by the analytical model and the experimental test are compared with numerical analysis. The validated analytical model was adapted to study a low-velocity impact; the lumped mass was associated with a rigid projectile, whose initial speed represents the impact velocity.

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.

Energy absorbed ability and damage analysis for honeycomb sandwich material of bio-inspired micro aerial vehicle under low velocity impact

2020 ◽  
pp. 095440622097542
Author(s):  
Jianxun Du ◽  
Peng Hao ◽  
Mabao Liu ◽  
Rui Xue ◽  
Lin’an Li
Keyword(s):  
Honeycomb Structure ◽  
Low Velocity Impact ◽  
Parameter Study ◽  
Low Velocity ◽  
Micro Aerial Vehicle ◽  
Thin Walled Structures ◽  
Wide Range ◽  
Aerial Vehicle ◽  
Thin Walled ◽  
The Impact

Because of the advantages of light weight, small size, and good maneuverability, the bio-inspired micro aerial vehicle has a wide range of application prospects and development potential in military and civil areas, and has become one of the research hotspots in the future aviation field. The beetle’s elytra possess high strength and provide the protection of the abdomen while being functional to guarantee its flight performance. In this study, the internal microstructure of beetle’s elytra was observed by scanning electron microscope (SEM), and a variety of bionic thin-walled structures were proposed and modelled. The energy absorption characteristics and protective performance of different configurations of thin-walled structures with hollow columns under impact loading was analyzed by finite element method. The parameter study was carried out to show the influence of the velocity of impactor, the impact angle of the impactor and the wall thickness of honeycomb structure. This study provides an important inspiration for the design of the protective structure of the micro aerial vehicle.

Low Velocity Impact Resistance of CPVC Pipes Exposed to Natural Outdoor Weathering Conditions

2012 ◽  
Vol 445 ◽  
pp. 959-964
Author(s):  
Z. Khan ◽  
Necar Merah ◽  
A. Bazoune ◽  
S. Furquan
Keyword(s):  
Impact Resistance ◽  
Outdoor Exposure ◽  
Impact Testing ◽  
Low Velocity Impact ◽  
Pipe Material ◽  
Low Velocity ◽  
Impact Energies ◽  
The Impact ◽  
Impact Events ◽  
Outdoor Weathering

Low velocity drop weight impact testing of CPVC pipes was conducted on 160 mm long pipe sections obtained from 4-inch (100 mm) diameter schedule 80 pipes. Impact test were carried out for the base (as received) pipes and after their exposure to out door natural weathering conditions in Dhahran, Saudi Arabia. The results of the impact testing on the natural (outdoor exposure) broadly suggest that the natural outdoor exposures produce no change in the impact resistance of CPVC pipe material for the impact events carrying low incident energies of 10 and 20J. At the impact energies of 35 and 50J the natural outdoor exposures appear to cause appreciable degradation in the impact resistance of the CPVC pipe material. This degradation is noted only for the longer exposure periods of 12 and 18 months.

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.

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