scholarly journals Damage Analysis and Experimental Study of Composite Structures with Initial Delamination

2019 ◽  
Vol 37 (4) ◽  
pp. 730-736
Author(s):  
Zhikai Wang ◽  
Zhipeng Chen ◽  
Nana Yang ◽  
Tao Yang
Keyword(s):  
Composite Materials ◽  
Bearing Capacity ◽  
Composite Laminates ◽  
Composite Structures ◽  
Load Capacity ◽  
Compression Modulus ◽  
Ultimate Bearing Capacity ◽  
Effective Length ◽  
Linear Segment ◽  
Two Parameters

Composite laminates are prone to delamination during hot pressing and cooling, this delamination is one of the most important defects that affect the properties of composite structures, the formation and propagation of delamination in composite materials can significantly reduce the structural strength of composite materials and even lead to catastrophic failure. In this paper, the two parameters of the initial stratified position and the initial stratified diameter are selected to research the effects of these two parameters on the mechanical properties of composite laminates through numerical simulation and experiment, and concludes that the influence of initial delamination along the thickness direction on the average compression modulus and strain of the linear segment is small; the influence of delamination on the ultimate bearing capacity increases with the decrease of the distance between the delamination and the center plane. When the diameter of the delamination is in the range of 8%~20% of the effective area(18~44 mm), the influence on the average compression modulus, ultimate bearing capacity and strain of the linear segment is not obvious. When the diameter is increased to 27% of the effective length(60 mm), the above properties have changed greatly. And then, this paper introduces the bilinear controlled cohesive elements into the progressive failure method to calculate the ultimate load capacity of composite laminates, and demonstrate the accuracy of the simulation method by experiments.

Damage detection of unidirectional carbon fiber–reinforced laminates with embedded magnetostrictive particulates: A preliminary study

2012 ◽  
Vol 24 (8) ◽  
pp. 991-1006 ◽  
Author(s):  
Oliver J Myers ◽  
George Currie ◽  
Jonathan Rudd ◽  
Dustin Spayde ◽  
Nydeia Wright Bolden
Keyword(s):  
Composite Materials ◽  
Carbon Fiber ◽  
Nondestructive Evaluation ◽  
Composite Laminates ◽  
Composite Structures ◽  
Single Layer ◽  
Polymeric Composite ◽  
Analytical Models ◽  
Fiber Reinforced ◽  
Carbon Fiber Reinforced

Defects in composite laminates are difficult to detect because of the conductive and paramagnetic properties of composite materials. Timely detection of defects in composite laminates can improve reliability. This research illustrates the preliminary analysis and detection of delaminations in carbon fiber laminate beams using a single layer of magnetostrictive particles and noncontacting concentric magnetic excitation and sensing coils. The baseline analytical models also begin to address the intrusive nature of the magnetostrictive particles as well as relate the applied excitation field with the stress and magnetic flux densities induced in the magnetostrictive layer. Numerical methods are used to begin to characterize the presence of magnetostrictive particles in the laminate and the behavior of the magnetostrictive particles in relationship to the magnetic field used during sensing. Unidirectional laminates with embedded delaminations are used for simulations and experimentations. A novel, yet simplified fabrication method is discussed to ensure consistent scanning and sensing capabilities. The nondestructive evaluation scanning experiments were conducted with various shapes and sizes of damages introduced into carbon fiber–reinforced polymeric composite structures. The results demonstrate high potential for magnetostrictive particles as a low-cost, noncontacting, and reliable sensor for nondestructive evaluation of composite materials.

Ultimate Bearing Capacity of Composition Columns Reinforced with the Prefabricated SHSCUS Filled with Steel Tubes Subjected to Axial Load

2011 ◽  
Vol 368-373 ◽  
pp. 225-229
Author(s):  
Guo Can Chen ◽  
Zhi Sheng Xu ◽  
Zhi Shuo Yang
Keyword(s):  
Bearing Capacity ◽  
Load Capacity ◽  
High Strength ◽  
Ultimate Bearing Capacity ◽  
Concrete Cover ◽  
Design Rule ◽  
Superposition Method ◽  
Steel Tubes ◽  
Ultimate Load Capacity ◽  
Concrete Type

This paper presents an experimental investigation on the short composition columns reinforced with the prefabricated super high strength concrete used stone-chop(abbreviated to SHSCUS) filled with steel tubes with 1RC as reference. The experimental parameters were the concrete type inner steel tubes, and L/D ratio, steel ratio and so on. The performance of the composition columns was investigated using different diameter-to-thickness ratio of steel tubes ranging from 15 to 26.6, and different cubic strength of 126.7, 120.3, 122.4, 134.4, 125.4, 111.4, 108.6MPa of infill concrete. The experimental results showed that concrete cover falling off was prior to specimens failure, and that the design rule, as specified in current code suitable for HSC overestimate the ultimate bearing capacity, were not suitable for the case with SHSCUS. Then the hypothesis was put forward based on experimental phenomena observed, and the formula of its ultimate load capacity was suggested based on superposition method, by which the predicted values have a good coincidence with those from the experiments.

EFFECT OF HYBRIDIZATION ON COMPRESSIVE PROPERTIES OF WOVEN CARBON, GLASS AND KEVLAR HYBRID COMPOSITES

2015 ◽  
Vol 76 (9) ◽  
Author(s):  
Norhafiza Muhammad ◽  
Aidah Jumahat ◽  
Nor Merlisa Ali
Keyword(s):  
Compressive Strength ◽  
Composite Materials ◽  
Hybrid Composite ◽  
Composite Laminates ◽  
Composite Structures ◽  
Hybrid Composites ◽  
Optical Microscope ◽  
Strain Diagram ◽  
Compressive Properties ◽  
Modes Of Failure

The growing use of high-performance materials, which are made of hybrid composite systems, has increased rapidly in engineering applications. Hybridization of woven carbon, glass and Kevlar fibre offers better mechanical properties of composite materials. This is also an effective way to reduce the cost of advanced composites. At the moment information on compressive properties of hybrid composites is very limited. It is well known that the compressive strength of composite materials is lower than the tensile strength. Therefore, compressive strength becomes one of the most important criteria in designing composite structures. Therefore, this research is aimed to evaluate the compressive properties of hybrid composites and compare to the properties of neat systems. Hybrid composite samples were fabricated using a vacuum bagging system. The compressive properties of Kevlar hybrid with carbon and glass composites were studied using an INSTRON 3382 universal machine with a constant crosshead speed of 1 mm/min. The compressive properties were determined based on the stress-strain diagram. It was observed that for hybrid composites, placing carbon woven cloth layers in the exterior and Kevlar woven cloth in the interior showed higher compressive strength than placing glass woven cloth layers in the exterior and Kevlar woven cloth in the interior. The modes of failure of the hybrid composite laminates were observed and evaluated using optical microscope and scanning electron microscopy (SEM).

Deformation Characteristics Research on Gravel Bed for Deep Buried Immerse Tunnel

2013 ◽  
Vol 353-356 ◽  
pp. 1480-1483 ◽  
Author(s):  
Yong Wang ◽  
Cai Hong Sun
Keyword(s):  
Particle Size ◽  
Bearing Capacity ◽  
Pile Foundation ◽  
Compression Modulus ◽  
Ultimate Bearing Capacity ◽  
Physical Model Test ◽  
Deformation Characteristics ◽  
Small Particle Size ◽  
Gravel Bed ◽  
Particle Size Gradation

Taking some deep buried immerse tunnel as background, deformation characteristics of foundation gravel bed is discussed by physical model test. The results show that small particle size gradation is not suitable for the foundation gravel bed, and compared with the non-groove gravel, compression modulus is greatly reduced in case of gravel with groove, and in case of pile foundation, gravel crushing phenomenon is obvious at the end of loading, and the ultimate bearing capacity of gravel bed is about 480kPa. If pile and gravel bed are used as the immerse tunnel foundation plan, it needs to take measure to control the stress level under the ultimate bearing capacity of gravel bed.

Behaviour of Composite Materials to Withstand Impact and Compressive Design Allowables

2007 ◽  
Vol 334-335 ◽  
pp. 305-308
Author(s):  
Zhen Shen ◽  
Sheng Chun Yang ◽  
Pu Hui Chen
Keyword(s):  
Composite Materials ◽  
Composite Laminates ◽  
Composite Structures ◽  
Evaluation System ◽  
Damage Tolerance ◽  
Damage Resistance ◽  
Large Numbers ◽  
Knee Point ◽  
The Relationship ◽  
Maximum Contact

In this paper the relationship between CAI and compressive design allowables of composite structures were discussed and it was pointed out that traditional CAI values could not reflect the behavior of composite materials to withstand impact adequately and no relationship between CAI values and compressive design allowables existed. Based on the integrity requirements of composite structures, it was pointed out that the evaluation system of composite materials to withstand impact should include both damage resistance and damage tolerance. Large numbers of test data verified that the knee point phenomenon of composite laminates to withstand impact existed. Based on failure mechanisms, it was proposed that the behavior evaluation system of composite systems to withstand impact was based on the properties at the knee point, that is, the maximum capability to keep integrity of the front plies (the maximum contact force) characterizing damage resistance and the threshold of dent depth(or impact energy)~compressive strength(or failure strain) curves characterizing damage tolerance.

The Ultimate Bearing Capacity Analysis of P.C. Bridge Based on Material Performance Degradation

2010 ◽  
Vol 163-167 ◽  
pp. 3391-3400 ◽  
Author(s):  
Peng Fei Xue ◽  
Da Ling Mao ◽  
Jin Feng Wang
Keyword(s):  
Bearing Capacity ◽  
Load Capacity ◽  
Limit State ◽  
Three Dimensional ◽  
Nonlinear Behavior ◽  
Ultimate Bearing Capacity ◽  
Load Factor ◽  
Capacity Analysis ◽  
Three Dimensional Model ◽  
Ultimate Load Capacity

During the service process of a P.C. bridge, the mechanical properties of materials (including concrete and steel) will deteriorate, and eventually result in the decrease of ultimate bearing capacity. Considering it’s structural behavior, degenerate solid elements were used to set up a three-dimensional model. By taking prestressed reinforcement as a part of structure, the equivalent nodal load was provided to calculate the effect of tensioning bars. The T.L. method was adopted to consider the geometric nonlinear effect. The Ohtani & Chen model was used to simulate the concrete material nonlinear behavior, and for prestressed steel strand and common reinforced, linear hardening and ideal elastoplastic model were adopted respectively. A P.C. continuous rigid frame bridge was employed for the case study, on the basis of material performance deterioration, the ultimate bearing capacity analysis of P.C. bridge structure was carried out. The results show that material deterioration has great impact on ultimate load capacity of structure: the load factor on limit state dropped rapidly from 13.9085 at t=0a to 7.8265 at t=100a, the corresponding safe index decreased from 2.265 to 1.581, and brittle characteristics was aggravated at the same time.

scholarly journals Defects and uncertainties of adhesively bonded composite joints

2021 ◽  
Vol 3 (9) ◽  
Author(s):  
Sadik Omairey ◽  
Nithin Jayasree ◽  
Mihalis Kazilas
Keyword(s):  
Composite Materials ◽  
Composite Structures ◽  
Production Efficiency ◽  
Adhesive Bonding ◽  
Detection Methods ◽  
Bonded Joints ◽  
Adhesively Bonded ◽  
Adhesively Bonded Joints ◽  
Wide Range ◽  
Bonded Composite

AbstractThe increasing use of fibre reinforced polymer composite materials in a wide range of applications increases the use of similar and dissimilar joints. Traditional joining methods such as welding, mechanical fastening and riveting are challenging in composites due to their material properties, heterogeneous nature, and layup configuration. Adhesive bonding allows flexibility in materials selection and offers improved production efficiency from product design and manufacture to final assembly, enabling cost reduction. However, the performance of adhesively bonded composite structures cannot be fully verified by inspection and testing due to the unforeseen nature of defects and manufacturing uncertainties presented in this joining method. These uncertainties can manifest as kissing bonds, porosity and voids in the adhesive. As a result, the use of adhesively bonded joints is often constrained by conservative certification requirements, limiting the potential of composite materials in weight reduction, cost-saving, and performance. There is a need to identify these uncertainties and understand their effect when designing these adhesively bonded joints. This article aims to report and categorise these uncertainties, offering the reader a reliable and inclusive source to conduct further research, such as the development of probabilistic reliability-based design optimisation, sensitivity analysis, defect detection methods and process development.

scholarly journals Introduction to Macroscopic Optimal Design in the Mechanics of Composite Materials and Structures

2021 ◽  
Vol 5 (2) ◽  
pp. 36
Author(s):  
Aleksander Muc
Keyword(s):  
Composite Materials ◽  
Composite Structures ◽  
Constitutive Relations ◽  
A Priori ◽  
Chemical Properties ◽  
Composite Plates ◽  
Failure Criteria ◽  
Lagrange Equations ◽  
Homogenization Methods ◽  
Mechanics Of Composite Materials

The main goal of building composite materials and structures is to provide appropriate a priori controlled physico-chemical properties. For this purpose, a strengthening is introduced that can bear loads higher than those borne by isotropic materials, improve creep resistance, etc. Composite materials can be designed in a different fashion to meet specific properties requirements.Nevertheless, it is necessary to be careful about the orientation, placement and sizes of different types of reinforcement. These issues should be solved by optimization, which, however, requires the construction of appropriate models. In the present paper we intend to discuss formulations of kinematic and constitutive relations and the possible application of homogenization methods. Then, 2D relations for multilayered composite plates and cylindrical shells are derived with the use of the Euler–Lagrange equations, through the application of the symbolic package Mathematica. The introduced form of the First-Ply-Failure criteria demonstrates the non-uniqueness in solutions and complications in searching for the global macroscopic optimal solutions. The information presented to readers is enriched by adding selected review papers, surveys and monographs in the area of composite structures.

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