Methods for Predicting Failure Behavior of Composite Materials

1979 ◽  
pp. 77-91 ◽  
Author(s):  
Shun-Chin Chou
Keyword(s):  
Composite Materials ◽  
Failure Behavior

Performance of All-Polypropylene Composites at LNG Temperatures

2017 ◽  
Author(s):  
Bilim Atli-Veltin
Keyword(s):  
Composite Materials ◽  
Mechanical Performance ◽  
Cost Effective ◽  
Tensile Tests ◽  
Small Scale ◽  
Failure Behavior ◽  
Polypropylene Composites ◽  
Design Flexibility ◽  
Static Tensile ◽  
Interlaminar Shear

In the small scale LNG infrastructure, composite materials are scarcely employed. Potentially, cost effective solutions for LNG applications could be developed thanks to the advantages of composite materials over metals such as weight savings, design flexibility and recyclability. The research presented in this paper focuses on the mechanical performance of fully recyclable, thermoplastic Polypropylene (PP) composite tapes at cryogenic LNG temperatures. Quasi-static tensile tests performed on [±45] laminates made of plain woven plies of PURE® show that at −196°C the behavior is bilinear with the failure strain of 6.5% and failure stress of 37 MPa. Such non-brittle failure behavior of PP is desirable for cryogenic applications. The other results presented in the paper contains [0/90] laminate results and the interlaminar shear strength characteristics at room and cryogenic temperatures.

scholarly journals Structural failure criterion for spatially-reinforced carbon-carbon composite materials

2020 ◽  
pp. 48-59
Author(s):  
I. V Magnitsky
Keyword(s):  
Composite Materials ◽  
Yield Stress ◽  
Carbon Composite ◽  
Biaxial Stress ◽  
Failure Behavior ◽  
Model Parameters ◽  
Elastic Model ◽  
Structural Cell ◽  
Carbon Composite Materials ◽  
Suggested Criterion

This paper defines the structural strength criterion for 4DL-reinforced carbon-carbon materials. For this scheme, fiber reinforcement consists of four groups of reinforcing elements, three of them are located in parallel planes with the angles of 120° between them and the fourth one is normal to them. The paper addresses the first failure of the material corresponding to its yield stress, in this point, one of the material components deviates from linear elastic behavior. A composite material is considered to be non-uniform structurally and consists of a matrix and reinforcing elements, rods. Those rods, in their turn, represent a unidirectional composite. To analyze the stress-strain state of individual components of the material, a three-level elastic model is built that uses the analytic approach at the micro level, while at higher levels it uses the finite element method. For numerical calculations, a structural cell of the material is taken. The boundary conditions provide small to negligible influence of the edge effects, thus simulating the behavior of the infinite volume of the material. For the material components, local strength criteria are introduced, where the fields of the criterion quantities are averaged over the volume of the structural cell. The strength surface of the material that corresponds to its first failure is obtained, and the conclusion is made that the suggested criterion provides a reasonable agreement with the available data on the typical carbon-carbon composite characteristics. Based on the calculated dependencies of the material’s yield stress on the load direction, a procedure is suggested to identify the model parameters based on the material failure behavior analysis using standard tensile and compressive tests. Estimated discrepancies between the results calculated using the suggested criterion and those obtained using the limiting stress criterion for biaxial stress states are given. It is shown that the discrepancy may reach tens of percent and in some cases the material strength increases in comparison with that in the uniaxial stress state. The results are subject to verification tests in order to verify the model for advanced spatially reinforced carbon-carbon composite materials.

Evaluation of Eddy Current Inspection on the Defects of Unloading vs. Loading Conditions in the Fiber Reinforced Composite Materials

2005 ◽  
Vol 475-479 ◽  
pp. 1063-1066
Author(s):  
Cheol Woong Kim ◽  
Jeong Soon Lee ◽  
Tae Gun Um ◽  
Dong Joon Oh ◽  
Il Song
Keyword(s):  
Composite Materials ◽  
Eddy Current ◽  
Failure Behavior ◽  
Specimen Thickness ◽  
Fiber Reinforced ◽  
Fiber Reinforced Composite ◽  
Reinforced Composite ◽  
Micro Cracks ◽  
Radial Loading ◽  
Phase Angles

It had been impossible to inspect the Eddy Current (EC) since the Fiber Reinforced Composite Materials (FRCM) had the low electric conductivity of resin layer. However, it has been successful for our previous research to inspect the defect using the EC. In the case of loading to FRCM, the researches of relationship between the failure behavior and the variation of EC signals have not been carried out. Therefore, this research focused on the comparison and the evaluation of the EC signals according to the variation of the defect depth using the unloading and the radial-loading FRCM tube. We obtained results are as follow. Firstly, The EC signals similar to that of the unloading specimens could be obtained from the loading specimen of 80% defect. Secondly, Regardless of the unloading and the loading specimens, the defect of 100% and 80% depths had the similar phase angles and Lissajous figures. Finally, it was guessed that the length of micro-cracks distributed at the whole specimens under the loading was less than 60% of the specimen thickness.

A dynamic crash model for energy absorption in braided composite materials - Part II: Implementation and verification

2011 ◽  
Vol 45 (8) ◽  
pp. 867-882 ◽  
Author(s):  
Nathan D. Flesher ◽  
Fu-Kuo Chang ◽  
Nageswara R. Janapala ◽  
J. Michael Starbuck
Keyword(s):  
Composite Materials ◽  
Energy Absorption ◽  
Composite Structures ◽  
Material Model ◽  
Element Model ◽  
Failure Behavior ◽  
Viscoplastic Material ◽  
Braided Composite ◽  
Rate Dependent ◽  
Crash Model

A dynamic crash model is developed and implemented to model the failure behavior and energy absorption of braided composite structures. Part I describes the development and theoretical foundation of a viscoplastic material model that captures the rate-dependent behavior present in braided composite materials. Part II presents the implementation of the model into a finite element model program and the experimental results for tubes crushed from quasi-static to 4000 mm/s rates used to verify the model. Energy absorption decreases sharply with an increase in crush rate, which is reflected in this model. Design concepts are also introduced to increase energy absorption in braided composites.

scholarly journals A Modified Compact Tension Test for Characterization of the Intralaminar Fracture Toughness of Tri-Axial Braided Composites

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 4890
Author(s):  
Michael May ◽  
Sebastian Kilchert ◽  
Tobias Gerster
Keyword(s):  
Fracture Toughness ◽  
Composite Materials ◽  
Crack Propagation ◽  
Compact Tension ◽  
Tension Test ◽  
Failure Behavior ◽  
Interlaminar Fracture Toughness ◽  
Interlaminar Fracture ◽  
Braided Composite ◽  
Compact Tension Test

The application of braided composite materials in the automotive industry requires an in-depth understanding of the mechanical properties. To date, the intralaminar fracture toughness of braided composite materials, typically used for describing post-failure behavior, has not been well-characterized experimentally. In this paper, a modified compact tension test, utilizing a relatively large specimen and a metallic loading frame, is used to measure the transverse intralaminar fracture toughness of a tri-axial braided composite. During testing, a relatively long fracture process zone ahead of the crack tip was observed. Crack propagation could be correlated to the failure of individual unit cells, which required failure of bias-yarns. The transverse interlaminar fracture toughness was found to be two orders of magnitude higher than the reference interlaminar fracture toughness of the same material. This is due to the fact, that intralaminar crack propagation requires breaking of fibers, which is not the case for interlaminar testing.

A Multiscale Framework for Designing High-Toughness Composite Materials

2019 ◽  
Vol 17 (05) ◽  
pp. 1940008
Author(s):  
Yan Li
Keyword(s):  
Fracture Toughness ◽  
Composite Materials ◽  
Ceramic Composites ◽  
Image Correlation ◽  
Analytical Models ◽  
Fracture Mechanisms ◽  
Interface Debonding ◽  
Failure Behavior ◽  
High Toughness ◽  
Fracture Simulation

Development of high-toughness composite materials requires careful microstructure design as geometric distribution of phases, constituent properties and interface attributes combine to influence the deformation and failure behavior of composites. In two-phase composite materials, reinforcement cracking and interface debonding are two competing fracture mechanisms observed during the crack–microstructure interactions. The activation of each fracture mechanism largely depends on the microstructure and ultimately determines the fracture toughness of composites. The objective of this study is to quantify the competition of the two fracture mechanisms as function of microstructure and find their intricate coupling with material fracture toughness. The multiscale material design framework developed here allows fracture toughness to be predicted through cohesive element-based fracture simulation and digital image correlation measurement. Based on the numerical and experimental results, two analytical models are developed for fracture mode determination of both brittle and ductile composites. Although calculations carried out concern ceramic composites Al2O3/SiC and metal matrix composites Al/SiC, the approach developed can be applied to other composite material systems.

A dynamic crash model for energy absorption in braided composite materials. Part I: Viscoplastic material model

2011 ◽  
Vol 45 (8) ◽  
pp. 853-865 ◽  
Author(s):  
Nathan D. Flesher ◽  
Fu-Kuo Chang ◽  
Nageswara R. Janapala
Keyword(s):  
Composite Materials ◽  
Energy Absorption ◽  
Composite Structures ◽  
Material Model ◽  
Failure Behavior ◽  
Structural Level ◽  
Viscoplastic Material ◽  
Braided Composite ◽  
Rate Dependent ◽  
Crash Model

A dynamic crash model is developed and implemented to model the failure behavior and energy absorption of braided composite structures. Part I describes the development and theoretical foundation of a viscoplastic material model that captures the rate-dependent behavior present in braided composite materials. Part II presents the implementation of the model into a FEM program and contains experimental results for tubes crushed from quasi-static rate to 4000 mm/s rates used to verify the model. The model is presented from the mesoscale to the structural scale, starting with the constitutive model applied to composite tow segments. Tow segment response is homogenized to determine the response of the braided unit cell, while consideration for braider tow rotation and stress concentration appear at the structural level.

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