scholarly journals An innovative fixture for testing the crashworthiness of composite materials

2020 ◽  
Vol 15 (55) ◽  
pp. 76-87
Author(s):  
Lorenzo Vigna ◽  
Iman Babaei ◽  
Ravin Garg ◽  
Giovanni Belingardi ◽  
Davide Salvatore Paolino ◽  
...  
Keyword(s):  
Composite Materials ◽  
Energy Absorption ◽  
Standard Procedure ◽  
Test Procedure ◽  
International Standards ◽  
Experimental Setup ◽  
Flat Specimen ◽  
Specific Energy Absorption ◽  
Impact Energies ◽  
Force Displacement

Despite the growing diffusion of composite materials in automotive and aerospace sectors, a standard procedure for testing their crashworthiness has not been developed yet. At present, the international standards for testing composite materials under impact conditions are not adequate to test their crush behavior. In this paper, a procedure for measuring the energy absorption due to the compressive crushing of a composite flat specimen, along its mid plane, is proposed. The experimental setup requires a fixture to hold the specimen and to avoid its buckling and an instrumented drop weight tower to obtain the force-displacement curves with the aim of calculating the Specific Energy Absorption. The paper will describe the adopted test procedure and some of the features of the newly developed experimental setup. The effectiveness of the procedure is demonstrated by testing several glass fiber-epoxy specimens under different impact energies.

Energy Absorption Characteristics of a Carbon Fiber Composite Automobile Lower Rail: A Comparative Study

2015 ◽  
Author(s):  
Muhammad Ali ◽  
Khairul Alam ◽  
Eboreime Ohioma
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Composite Materials ◽  
Carbon Fiber ◽  
Energy Absorption ◽  
Reactive Force ◽  
Element Analysis ◽  
Cross Sectional Dimension ◽  
Force Displacement ◽  
Absorption Characteristics

Composite materials have emerged as promising materials in applications where low weight and high strengths are desired. Aerospace industry has been using composite materials for past several decades exploiting their characteristics of high strength to weight ratio over conventional homogenous materials. To provide a wider selection of materials for design optimization, and to develop lighter and stronger vehicles, automobile industries have been exploring the use of composites for a variety of components, assemblies, and structures. Composite materials offer an attractive alternate to traditional metals as designers have greater flexibility to optimize material and structural shapes according to functional requirements. However, any automotive structure or part constructed from composite materials must meet or exceed crashworthiness standards such as Federal Motor Vehicle Safety Standard (FMVSS) 208. Therefore, for a composite structure designed to support the integrity of the automotive structure and provide impact protection, it is imperative to understand the energy absorption characteristics of the candidate composite structures. In the present study, a detailed finite element analysis is presented to evaluate the energy absorbing characteristics of a carbon fiber reinforced polymer composite lower rail, a critical impact mitigation component in automotive chassis. For purposes of comparison, the analysis is repeated with equivalent aluminum and steel lower rails. The study was conducted using ABAQUS CZone module, finite element analysis software. The rail had a cross-sectional dimension of 62 mm (for each side), length of 457.2 mm, and a wall thickness of 3.016 mm. These values were extracted from automobile chassis manufacturer’s catalog. The rail was impacted by a rigid plate of mass 1 tonne (to mimic a vehicle of 1000 Kg gross weight) with an impact velocity of 35 mph (15646.4 mm/s), which is 5 mph over the FMVSS 208 standard, along its axis. The simulation results show that the composite rail crushes in a continuous manner under impact load (in contrast to a folding collapse deformation mode in aluminum and steel rails) which generates force-displacement curve with invariable crushing reactive force for the most part of the crushing stroke. The energy curves obtained from reactive force-displacement graphs show that the composite rail absorbs 240% and 231% more energy per unit mass as compared to aluminum and steel rails. This shows a significant performance enhancement over equivalent traditional metal (aluminum and steel) structures and suggests that composite materials in conjunction with cellular materials/configurations have a tremendous potential to improve crashworthiness of automobiles while offering opportunities of substantial weight reductions.

scholarly journals Study on improvement of prefolded energy absorption device to constant resistance and its mechanical properties

2021 ◽  
Vol 104 (3) ◽  
pp. 003685042110368
Author(s):  
Dong An ◽  
Jiaqi Song ◽  
Hailiang Xu ◽  
Jingzong Zhang ◽  
Yimin Song ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Energy Absorption ◽  
Compression Test ◽  
Side Wall ◽  
Concave Side ◽  
Displacement Curve ◽  
Static Compression ◽  
Constant Resistance ◽  
The Impact ◽  
Force Displacement

When the rock burst occurs, energy absorption support is an important method to solve the impact failure. To achieve constant resistance performance of energy absorption device, as an important component of the support, the mechanical properties of one kind of prefolded tube is analyzed by quasi-static compression test. The deformation process of compression test is simulated by ABAQUS and plastic strain nephogram of the numerical model are studied. It is found that the main factors affecting the fluctuation of force-displacement curve is the stiffness of concave side wall. The original tube is improved to constant resistance by changing the side wall. The friction coefficient affects the folding order and form of the energy absorbing device. Lifting the concave side wall stiffness can improve the overall stiffness of energy absorption device and slow down the falling section of force-displacement curve. It is always squeezed by adjacent convex side wall in the process of folding, with large plastic deformation. Compared with the original one, the improved prefolded tube designed in this paper can keep the maximum bearing capacity ( Pmax), increase the total energy absorption ( E), improve the specific energy absorption (SEA), and decrease the variance ( S2) of force-displacement curve.

Dynamic Axial Compression of Square CFRP/Aluminium Tubes

2019 ◽  
Vol 794 ◽  
pp. 202-207
Author(s):  
Rafea Dakhil Hussein ◽  
Dong Ruan ◽  
Guo Xing Lu ◽  
Jeong Whan Yoon ◽  
Zhan Yuan Gao
Keyword(s):  
Energy Absorption ◽  
Specific Energy ◽  
Fibre Composite ◽  
Dynamic Tests ◽  
Carbon Fibre Composite ◽  
Specific Energy Absorption ◽  
Static Tests ◽  
Crushing Force ◽  
Cfrp Tubes ◽  
The Impact

Carbon fibre composite tubes have high strength to weight ratios and outstanding performance under axial crushing. In this paper, square CFRP tubes and aluminium sheet-wrapped CFRP tubes were impacted by a drop mass to investigate the effect of loading velocity on the energy absorption of CFRP/aluminium tubes. A comparison of the quasi-static and dynamic crushing behaviours of tubes was made in terms of deformation mode, peak crushing force, mean crushing force, energy absorption and specific energy absorption. The influence of the number of aluminium layers that wrapped square CFRP tubes on the crushing performance of tubes under axial impact was also examined. Experimental results manifested similar deformation modes of tubes in both quasi-static and dynamic tests. The dynamic peak crushing force was higher than the quasi-static counterpart, while mean crushing force, energy absorption and specific energy absorption were lower in dynamic tests than those in quasi-static tests. The mean crushing force and energy absorption decreased with the crushing velocity and increased with the number of aluminium layers. The impact stroke (when the force starts to drop) decreased with the number of aluminium layers.

scholarly journals Energy Absorption Characteristics of PVC Coarse Aggregate Concrete under Impact Load

2021 ◽  
Vol 15 (1) ◽  
Author(s):  
Shi Hu ◽  
Huaming Tang ◽  
Shenyao Han
Keyword(s):  
Compressive Strength ◽  
Energy Absorption ◽  
High Speed ◽  
Coarse Aggregate ◽  
Specific Energy Absorption ◽  
Low Speed ◽  
High Speed Impact ◽  
Aggregate Content ◽  
Dynamic Compressive Strength ◽  
Absorption Characteristics

AbstractIn this paper, polyvinyl chloride (PVC) coarse aggregate with different mixing contents is used to solve the problems of plastic pollution, low energy absorption capacity and poor damage integrity, which provides an important reference for PVC plastic concrete used in the initial support structures of highway tunnels and coal mine roadway. At the same time, the energy absorption characteristics and their relationship under different impact loads are studied, which provides an important reference for predicting the energy absorption characteristics of concrete under other PVC aggregate content or higher impact speed. This study replaced natural coarse aggregate in concrete with different contents and equal volume of well-graded flaky PVC particles obtained by crushing PVC soft board. Also, slump, compression, and splitting strength tests, a free falling low-speed impact test of steel balls and a high-speed impact compression test of split Hopkinson pressure bar (SHPB) were carried out. Results demonstrate that the static and dynamic compressive strength decreases substantially, and the elastic modulus and slump decrease slowly with the increase of the mixing amount of PVC aggregate (0–30%). However, the energy absorption rate under low-speed impact and the specific energy absorption per MPa under high-speed impact increase obviously, indicating that the energy absorption capacity is significantly enhanced. Regardless of the mixing amount of PVC aggregate, greater strain rate can significantly enhance the dynamic compressive strength and the specific energy absorption per MPa. After the uniaxial compression test or the SHPB impact test, the relative integrity of the specimen is positively correlated with the mixing amount of PVC aggregate. In addition, the specimens are seriously damaged with the increase of the impact strain rate. When the PVC aggregate content is 20%, the compressive strength and splitting strength of concrete are 33.8 MPa and 3.26 MPa, respectively, the slump is 165 mm, the energy absorption rate under low-speed impact is 89.5%, the dynamic compressive strength under 0.65 Mpa impact air pressure is 58.77 mpa, and the specific energy absorption value per MPa is 13.33, which meets the requirements of shotcrete used in tunnel, roadway support and other impact loads. There is a linear relationship between the energy absorption characteristics under low-speed impact and high-speed impact. The greater the impact pressure, the larger the slope of the fitting straight line. The slope and intercept of the fitting line also show a good linear relationship with the increase of impact pressure. The conclusions can be used to predict the energy absorption characteristics under different PVC aggregate content or higher-speed impact pressure, which can provide important reference for safer, more economical, and environmental protection engineering structure design.

Evaluation Method of U-Bolt Energy Absorption

2009 ◽  
Author(s):  
Eiji Shirai ◽  
Tetsuya Zaitsu ◽  
Kazutoyo Ikeda ◽  
Toshiaki Yoshii ◽  
Masami Kondo ◽  
...  
Keyword(s):  
Energy Absorption ◽  
Evaluation Method ◽  
Design Procedure ◽  
Piping System ◽  
Design Technique ◽  
Dynamic Tests ◽  
Key Issues ◽  
Static And Dynamic Tests ◽  
Force Displacement ◽  
Rigid Design

At domestic PWR plants in Japan, one of the major key issues is earthquake-proof safety [1–3]. Recently, a design procedure using energy absorption, not conventional rigid design, was authorized according to revised review guidelines for aseismic design (JEAC4601). Therefore, we focused on the design technique that utilizes energy absorption effects to reduce the seismic responses of the piping system with U-Bolt, by the static and dynamic tests of simplified piping model supported by U-Bolt. The force-displacement characteristics and a fatigue diagram were obtained by the tests.

scholarly journals Assessing the undrained strength of very soft clays in the SPT

2021 ◽  
Vol 44 (4) ◽  
pp. 1-6
Author(s):  
Francisco Lopes ◽  
Osvangivaldo Oliveira ◽  
Marcio Almeida
Keyword(s):  
Standard Procedure ◽  
Soft Clay ◽  
Test Procedure ◽  
State Theory ◽  
Technical Note ◽  
Construction Site ◽  
Soft Clays ◽  
Design Engineers ◽  
Present Information ◽  
Undrained Strength

The log of a SPT in very soft clay may simply indicate a zero blow-count, or present information on the penetration – under self-weight – of the composition (sampler, rods and hammer) as recommended by some standards. The second type of information is often disregarded by design engineers due to the lack of a standard procedure for measuring these penetrations or because the test is regarded as not sensitive enough to give an indication on the undrained shear strength of soft clays. The penetration under the composition’s selfweight, however, can indicate the magnitude of Su, which, along with other more specific and sensitive tests, can help in assessing the spatial distribution of clay consistency in a large deposit. A proposed test procedure and interpretation had been given in an earlier technical note. This note presents an extended formulation and an evaluation of Su via the SPT at a construction site in Rio de Janeiro, including comparisons with results of piezocone and vane tests. The values of Su obtained with the SPT lie between the profiles given by vane tests, corrected by Plasticity Index, and the Critical State Theory, the latter representing a lower bound to the clay strength.

Ballistic Performance Evaluation of Kevlar-Glass Fibre Hybrid Composite Laminate against Medium Velocity Impact

2021 ◽  
Vol 1165 ◽  
pp. 47-64
Author(s):  
Saurabh S. Kumar ◽  
Rajesh G. Babu ◽  
U. Magarajan
Keyword(s):  
Energy Absorption ◽  
Specific Energy ◽  
Glass Fibre ◽  
Hybrid Composite ◽  
Composite Laminates ◽  
Areal Density ◽  
Ballistic Performance ◽  
Performance Requirement ◽  
Specific Energy Absorption ◽  
Fabric Composite

In this paper, the post ballistic impact behaviour of kevlar-glass fibre hybrid composite laminates was investigated against 9×19 mm projectile. Eight different types of composite laminates with different ratios of kevlar woven fibre to glass fibre were fabricated using hand lay-up with epoxy matrix. Ballistic behaviour like ballistic Limit (V50), energy absorption, specific energy absorption and Back Face Signature (BFS) were studied after bullet impact. The results indicated that as the Percentage of glass fibre is increased there was a linear increment in the ballistic behaviour. Addition of 16% kevlar fabric, composite sample meets the performance requirement of NIJ0101.06 Level III-A. Since the maximum specific energy absorption was observed in Pure Kevlar samples and the adding of glass fibre increases the weight and Areal Density of the sample, further investigations need to be carried out to utilize the potential of glass fibre for ballistic applications.

Enhancement in specific energy absorption of invertubes

2019 ◽  
Vol 159 ◽  
pp. 424-440 ◽  
Author(s):  
T.J. Reddy ◽  
V. Narayanamurthy ◽  
Y.V.D. Rao
Keyword(s):  
Energy Absorption ◽  
Specific Energy ◽  
Specific Energy Absorption

scholarly journals Thermal Modelling of a Prismatic Lithium-Ion Cell in a Battery Electric Vehicle Environment: Influences of the Experimental Validation Setup

Energies ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 62 ◽  
Author(s):  
Jan Kleiner ◽  
Lidiya Komsiyska ◽  
Gordon Elger ◽  
Christian Endisch
Keyword(s):  
Electric Vehicle ◽  
Test Procedure ◽  
Lithium Ion ◽  
Constant Current ◽  
Experimental Setup ◽  
Battery Electric Vehicle ◽  
Spatially Resolved ◽  
Lithium Ion Cell ◽  
Static And Dynamic Loads ◽  
Prismatic Cell

In electric vehicles with lithium-ion battery systems, the temperature of the battery cells has a great impact on performance, safety, and lifetime. Therefore, developing thermal models of lithium-ion batteries to predict and investigate the temperature development and its impact is crucial. Commonly, models are validated with experimental data to ensure correct model behaviour. However, influences of experimental setups or comprehensive validation concepts are often not considered, especially for the use case of prismatic cells in a battery electric vehicle. In this work, a 3D electro–thermal model is developed and experimentally validated to predict the cell’s temperature behaviour for a single prismatic cell under battery electric vehicle (BEV) boundary conditions. One focus is on the development of a single cell’s experimental setup and the investigation of the commonly neglected influences of an experimental setup on the cell’s thermal behaviour. Furthermore, a detailed validation is performed for the laboratory BEV scenario for spatially resolved temperatures and heat generation. For validation, static and dynamic loads are considered as well as the detected experimental influences. The validated model is used to predict the temperature within the cell in the BEV application for constant current and Worldwide harmonized Light vehicles Test Procedure (WLTP) load profile.

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