scholarly journals Resistance to the piercing of composite materials

2018 ◽  
Vol 19 (6) ◽  
pp. 540-543
Author(s):  
Lesław Kyzioł
Keyword(s):  
Composite Materials ◽  
High Strain ◽  
Physical Nonlinearity ◽  
Impact Loads ◽  
Strain Rates ◽  
Test Results ◽  
The Impact ◽  
The Mathematical Model ◽  
Different Thickness ◽  
Optimal Calculation

For structures that carry dynamic loads, the requirements are imposed for safety reasons. The requirements apply to both materials and construction. This requires searching for optimal calculation methods, including geometric and physical nonlinearity, which are results from the construction of the structure. An example is various ballistic structures (ballistic shields), which are hit by bullets in which huge energy is accumulated. In this case, the hitting in the shield with a bullet can be considered as a load due to mass impact. Loads at high strain rates are described by various mathematical models. The mathematical model is complex because a large number of "coefficients" is required, moreover, the obtained test results are not always repeatable. The paper presents the results of shooting multilayer plates with composite materials with 7.62 mm caliber bullets. The shield consisted of three layers, the outer layers were steel or aluminum, the inner layer was natural or modified wood. The samples had the shape of a shield and were 50 mm in diameter and of different thickness. The results of the research allowed to assess the impact of wood modification on its puncture resistance.

scholarly journals Evaluation of Energy Absorption Capabilities of Polyethylene Foam under Impact Deformation

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3613
Author(s):  
Baohui Yang ◽  
Yangjie Zuo ◽  
Zhengping Chang
Keyword(s):  
Energy Absorption ◽  
Failure Modes ◽  
High Strain ◽  
Early Stage ◽  
High Energy ◽  
Test Method ◽  
Test Theory ◽  
Strain Rates ◽  
Impact Properties ◽  
The Impact

Foams are widely used in protective applications requiring high energy absorption under impact, and evaluating impact properties of foams is vital. Therefore, a novel test method based on a shock tube was developed to investigate the impact properties of closed-cell polyethylene (PE) foams at strain rates over 6000 s−1, and the test theory is presented. Based on the test method, the failure progress and final failure modes of PE foams are discussed. Moreover, energy absorption capabilities of PE foams were assessed under both quasi-static and high strain rate loading conditions. The results showed that the foam exhibited a nonuniform deformation along the specimen length under high strain rates. The energy absorption rate of PE foam increased with the increasing of strain rates. The specimen energy absorption varied linearly in the early stage and then increased rapidly, corresponding to a uniform compression process. However, in the shock wave deformation process, the energy absorption capacity of the foam maintained a good stability and exhibited the best energy absorption state when the speed was higher than 26 m/s. This stable energy absorption state disappeared until the speed was lower than 1.3 m/s. The loading speed exhibited an obvious influence on energy density.

Response of Various Metals to Large Torsional Strains Over a Large Range of Strain Rates—Part 1: Ductile Metals

1983 ◽  
Vol 105 (1) ◽  
pp. 42-47 ◽  
Author(s):  
G. R. Johnson ◽  
J. M. Hoegfeldt ◽  
U. S. Lindholm ◽  
A. Nagy
Keyword(s):  
Large Range ◽  
High Strain ◽  
Strain Rates ◽  
Test Results ◽  
Ductile Metals ◽  
Positive Strain ◽  
Lower Strain ◽  
Torsional Test ◽  
Shear Strains ◽  
Nickel 200

This paper presents torsional test results for six ductile metals subjected to large shear strains and high strain rates. Included are OFHC copper, Cartridge brass, Nickel 200, Armco IF iron, Carpenter electrical iron, and 1006 steel. Torsional shear strains as high as 700 percent are achieved and strain rates vary from quasi-static to over 300 s−1. At the lower strain rates all of the materials exhibit positive strain hardening and strain rate hardening under essentially isothermal conditions. At the higher strain rates there is significant adiabatic thermal softening and strong evidence for shear instabilities and localizations. Constitutive relationships are derived from the test data and finite element computations of the tests are performed.

Experimental and Numerical Investigation on the Load Carrying Behavior of Large Ship Windows

2014 ◽  
Author(s):  
Wolfgang Fricke ◽  
Bjarne Gerlach ◽  
Matthias Guiard
Keyword(s):  
Ultimate Load ◽  
Impact Loads ◽  
Test Results ◽  
Lateral Loads ◽  
Load Range ◽  
Filled Rubber ◽  
Load Carrying ◽  
Drop Tests ◽  
Load Tests ◽  
The Impact

Aboard ships windows are exposed to static as well as dynamic loads, e.g. impact loads. Failure can lead to serious consequences. Therefore two research projects were initiated in order to analyze the load carrying behavior of windows. In addition to quasi-static ultimate load tests and drop tests with water filled rubber bags special attention is paid to the Finite Element (FE) modeling. In particular the response — stresses and deformations — to quasi-static lateral loads can be calculated with good agreement to test results. Hence FE calculations can be useful to determine and compare failure mechanisms of different window designs. An ultimate load range can be estimated by taking into account the breaking strength range of glass. A comparison between FE calculations and results of the impact tests showed that these are sensitive to conditions which could hardly be measured during the test, e.g. the shape of the approaching water-filled rubber bag. Varying of parameters eventually yielded that window response to impact loads can also be calculated sufficiently, at least, to evaluate different window designs. Further investigations on this topic are in progress.

Stress-strain behavior of carbon filament yarns under high strain rates

2012 ◽  
Vol 82 (7) ◽  
pp. 685-699 ◽  
Author(s):  
Ayham Younes ◽  
Vignaesh Sankaran ◽  
André Seidel ◽  
Martin Waldmann ◽  
Chokri Cherif ◽  
...  
Keyword(s):  
High Speed ◽  
Test Method ◽  
Fiber Reinforced Composites ◽  
Impact Loads ◽  
Strain Rates ◽  
Reinforced Composites ◽  
Test Results ◽  
Fiber Reinforced ◽  
Carbon Filament ◽  
Extreme Stress

Fiber-reinforced composites used in numerous technical applications have to meet the ever increasing safety requirements. Resistance to extreme stress under high velocity impact loads assumes even greater significance. Previous studies on the behavior of fiber-reinforced composites under impact loads provide little insight about the properties of filament yarns, a basis for many composite applications. Hence this paper focuses on the development of a suitable test method for performing high speed tensile tests on all filament yarn types, and the acquisition and analysis of the test results. This will enable the derivation of material models for their usage in the field of composites applications. Initially, the widely used carbon fiber filament yarns have been tested. The conclusive test results with a reduced yarn clamp mass and high stiffness of the test apparatus indicate that tensile strength and modulus of elasticity of carbon filament yarns increase with higher strain rates.

Stress Wave Propagation for Nonlinear Viscoelastic Polymeric Materials at High Strain Rates

2003 ◽  
Vol 19 (1) ◽  
pp. 177-183 ◽  
Author(s):  
Li-Lih Wang
Keyword(s):  
Wave Propagation ◽  
High Frequency ◽  
High Strain ◽  
Polymeric Materials ◽  
Elastic Response ◽  
Stress Wave Propagation ◽  
Strain Rates ◽  
High Strain Rates ◽  
Nonlinear Viscoelastic ◽  
The Impact

ABSTRACTWithout knowing the dynamic constitutive relation of materials under high strain rates, no wave propagation can be correctly analyzed. A Series of experimental and theoretical investigation at high strain rates revealed that the nonlinear viscoelastic behavior of polymers and the related composites are well described by the Zhu-Wang-Tang (ZWT) nonlinear viscoelastic constitutive equation. The impulsive reponse of ZWT materials consists of a rate independent nonlinear elastic response and a high frequency linear viscoelastic response. The dispersion and attenuation of nonlinear viscoelastic waves mainly depend on the effective nonlinearity and the high frequency relaxation time θ2. An “effective influence distance” or “effective influence time” is defined to characterize the wave propagation range where θ2 dominates the impact relaxation process.

Characterization of a Ferritic Stainless Sheet Steel in Simple Shear and Uniaxial Tension at Different Strain Rates

2011 ◽  
Author(s):  
Matti Isakov ◽  
Jeremy Seidt ◽  
Kauko O¨stman ◽  
Amos Gilat ◽  
Veli-Tapani Kuokkala
Keyword(s):  
Uniaxial Tension ◽  
Simple Shear ◽  
High Strain ◽  
Image Correlation ◽  
Materials Testing ◽  
Strain Rates ◽  
Test Results ◽  
High Strain Rates ◽  
Stress Strain

In this study the mechanical properties of ferritic stainless steel EN 1.4521 (AISI 444) were characterized in uniaxial tension and simple shear. The specimen geometries were designed so that tests could be carried out both with a conventional uniaxial materials testing machine and at high strain rates with the Tensile Hopkinson Split Bar method. During the tests, specimen surface deformation was measured using a three dimensional digital image correlation technique based on a two-camera stereovision setup. This technique allowed direct measurement of the specimen gauge section deformation during the test. Test results indicate that the selected approach is suitable for large strain plastic deformation characterization of ductile metals. The stress-strain data obtained from the simple shear tests shows a correlation with the tensile test results according to the von Mises effective stress-strain criterion. Since necking is absent in shear, test data can be obtained at considerably higher plastic strains than in tension. However, the final fracture occurs under a complex loading mode due to the distortion of the specimen geometry and multiaxial loading introduced by the simple shear arrangement. Test results also show that reliable material data can be obtained at high strain rates.

Evaluation of Dynamic Properties of Wood-Plastic Composites Using Split Hopkinson Bar Methods

2016 ◽  
Vol 715 ◽  
pp. 23-26
Author(s):  
Masahiro Nishida ◽  
Shun Furuya ◽  
Hirokazu Ito ◽  
Rie Makise ◽  
Masaki Okamoto
Keyword(s):  
High Strain ◽  
Dynamic Properties ◽  
Wood Flour ◽  
Impact Resistance ◽  
Strain Rates ◽  
High Strain Rates ◽  
Wood Plastic Composites ◽  
Plastic Composites ◽  
Pressure Bar ◽  
The Impact

Wood-plastic composites (WPCs) which consist of wood flour and plastics have been widely used as architectural materials for a long time. However, the impact resistance is not always high and basic mechanical properties at high strain rate are not fully understood. In order to clarify the tensile behavior at high strain rates, split Hokinson pressure bar method was used for WPCs consisting of polypropylene. The effects of mixing ratio on the maximum stress and elongation at break were examined at high strain rates.

Response of Various Metals to Large Torsional Strains Over a Large Range of Strain Rates—Part 2: Less Ductile Metals

1983 ◽  
Vol 105 (1) ◽  
pp. 48-53 ◽  
Author(s):  
G. R. Johnson ◽  
J. M. Hoegfeldt ◽  
U. S. Lindholm ◽  
A. Nagy
Keyword(s):  
Large Range ◽  
High Strain ◽  
Tungsten Alloy ◽  
Strain Rates ◽  
Test Results ◽  
Low Alloy Steel ◽  
Ductile Metals ◽  
Torsional Test ◽  
Shear Strains ◽  
Strain Rate Hardening

This paper presents torsional test results for six metals subjected to large shear strains and high strain rates. Included are 2024-T351 aluminum, 7039 aluminum, low alloy steel, S-7 tool steel, tungsten alloy and DU-.75Ti (Depleted Uranium). The specimens are strained to fracture at strain rates from quasi-static to over 100 s−1. All of the materials exhibit strain hardening and strain rate hardening. At the higher strain rates some of the materials develop shear instabilities and localizations. Constitutive relationships are derived from the test data and finite element computations of the tests are performed.

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