A Lattice Model for Stress Wave Propagation in Composite Materials

1973 ◽  
Vol 40 (1) ◽  
pp. 149-154 ◽  
Author(s):  
D. S. Drumheller ◽  
H. J. Sutherland
Keyword(s):  
Composite Materials ◽  
Wave Front ◽  
Lattice Model ◽  
Aluminum Matrix ◽  
Laminated Plates ◽  
Stress Wave Propagation ◽  
Wide Range ◽  
Precise Shape ◽  
The Matrix ◽  
Specific Material

Geometric dispersion, observed in a wide variety of composite materials, is believed to result mainly from the relatively periodic arrangement of the reinforcing elements in the matrix rather than from the precise shape of each reinforcing element. On the basis of this observation, a lattice model for composite materials which ignores the shape of the reinforcing elements but preserves their periodicity has been developed. For a wide range of engineering applications, this model can be used to predict the behavior of actual engineering composites. In the application of the lattice model to a specific material, consideration of the dispersive characteristics of the composite are set aside, initially, and the composite is treated as a nondispersive homogeneous mixture. The effective or average properties of the mixture are determined either by steady-wave analysis or appropriate experiments. A lattice is then formed by redistributing the mass within the mixture to form a periodic structure of laminated plates. This mass redistribution is carried out in a manner which yields a lattice with theoretical dispersive characteristics that match the measured dispersive characteristics of the composite. The model was applied to composites consisting of a regular array of tungsten fibers in an aluminum matrix and composed of 2.2 and 22.1 percent by volume of tungsten. Two flyer-plate experiments were performed in the plastic range of the composite. The agreement between experiment and calculation for the arrival time and rise time of the wave front and for the frequency of the ringing behind the wave front is good.

scholarly journals Sensitivity Analysis for the Spring-in of Composite Shells

2011 ◽  
Vol 20 (5) ◽  
pp. 096369351102000
Author(s):  
Chensong Dong
Keyword(s):  
Sensitivity Analysis ◽  
Thermal Expansion ◽  
Composite Materials ◽  
Design Of Experiments ◽  
Composite Shells ◽  
Dimensional Control ◽  
Surface Method ◽  
Wide Range ◽  
The Matrix ◽  
Dimensional Variation

Composite materials are a class of engineering materials widely used in a wide range of industries. Spring-in is a common dimensional variation of composite shells. It is well known that spring-in is dependent on many factors e.g. the constituent properties and coefficients of thermal expansion (CTE). A sensitivity analysis on the spring-in is presented in this paper. The sensitivities of the spring-in to the constituent properties and CTE are studied by the Design of Experiments (DOE) and the Response Surface Method (RSM). It is shown that the spring-in is predominantly sensitive to the Poisson's ratio of the matrix and the transverse CTE of the fibres. The results can be used to estimate the uncertainty of the spring-in from the uncertainties of the constituent properties and CTE, which is potentially useful for the design of composite products with improved dimensional control.

Composite Materials Based on EN AW-Al Cu4Mg1(A) Aluminum Alloy Reinforced with the Ti(C,N) Ceramic Particles

2006 ◽  
Vol 530-531 ◽  
pp. 243-248 ◽  
Author(s):  
Leszek Adam Dobrzański ◽  
Anna Włodarczyk-Fligier ◽  
Marcin Adamiak
Keyword(s):  
Aluminum Alloy ◽  
Composite Materials ◽  
Uniform Distribution ◽  
Matrix Material ◽  
Aluminum Matrix ◽  
Tensile Tests ◽  
Reinforcing Particles ◽  
Hardness Tests ◽  
Strength Tests ◽  
The Matrix

Investigations of composite materials based on EN AW-Al Cu4Mg1(A) aluminum alloy reinforced with the Ti(C,N) particles with various weight ratios of 5, 10, and 15% are presented. Powders of the starting materials were mixed in the laboratory vibratory ball mill to acquire the uniform distribution of reinforcement particles in the matrix material. The components were initially compacted at cold state in a die with the diameter of ∅ 26 mm in the laboratory vertical unidirectional press – with a capacity of 350 kN. The obtained P/M compacts were heated to a temperature of 480÷500°C and finally extruded – with the extrusion pressure of 500 kN. Bars with a diameter of 8 mm were obtained as the end product. Based on the microstructural examinations of the obtained composite materials, the uniform distribution of the reinforcing particles in the aluminum matrix was revealed. Hardness tests, tensile tests and the ultimate compressive strength tests made it possible demonstrate that all these properties change along with the reinforcing particles concentration change.

scholarly journals Energy absorption capability of laminated plates made of fully thermoplastic composite

2018 ◽  
Vol 232 (8) ◽  
pp. 1389-1401 ◽  
Author(s):  
Simonetta Boria ◽  
Alessandro Scattina
Keyword(s):  
Energy Absorption ◽  
Laminated Plates ◽  
Thermoplastic Composite ◽  
Low Velocity Impact ◽  
Thermoplastic Composites ◽  
Fibre Reinforcement ◽  
Low Velocity ◽  
Wide Range ◽  
The Matrix ◽  
The Impact

The behaviour of composites materials, made of synthetic fibres embedded in a thermoplastic resin, subjected to low velocity impacts, was largely studied in the past. However, in the last years, the use of thermoplastic composites has been increased due to the considerable advantages in terms of recyclability of this family of materials. Thermoplastic composites are composed of polymers with different material’s structure if compared to the more traditional thermoset composite. Consequently, the behaviour of these materials can be different in some loading conditions. Moreover, considering the wide range of thermoplastic composites that have been developed in the last years, the study of the behaviour of these materials, in case of impact, has not been yet widely analysed, in particular considering materials where both the matrix and the reinforcement are made of thermoplastic. In this perspective, the goal of this work is to study the behaviour of a new thermoplastic composite (PURE thermoplastic) in conditions of low velocity impact. In this material, the matrix and the fibre reinforcement are made of polypropylene both. The paper presents the results of an experimental investigation. In particular, a series of impact tests with a drop dart equipment have been carried out on laminates made of PURE thermoplastic. Laminates with different thicknesses have been taken into consideration. The influence of the impact conditions on the material’s behaviour has been investigated and the capability of energy absorption has been studied. The PURE thermoplastic showed a different behaviour in terms of energy absorption and damage mechanisms if compared to the composites presented in the literature. The thickness of the laminate has had influence on the deformation and the damage mechanism of the specimens: with low thickness, the perforation of the specimen has been obtained, whereas, with the higher thickness, the specimens have shown a ductile behaviour and extended plasticity without crack tip. The contact force between the dart and the specimen has been influenced by the energy level of the impact, but with an opposite trend if compared to that of the composites studied in the literature.

Numerical Study of Residual Thermal Stresses in MMC

2020 ◽  
Vol 22 (4) ◽  
pp. 1099-1110
Author(s):  
Tayeb Nehari
Keyword(s):  
Residual Stresses ◽  
Thermal Stresses ◽  
Numerical Study ◽  
Aluminum Matrix ◽  
Internal Stresses ◽  
Thermal Residual Stresses ◽  
Wide Range ◽  
The Matrix ◽  
Silicon Carbide Particles ◽  
Carbide Particles

AbstractIn this paper, numerical study analysis of residual thermal stresses in aluminum matrix reinforced with silicon carbide particles with double-crack has been carried out. is studied in order to determine the thermo-mechanical behavior under the effect of different temperature gradients during cooling. For a more realistic simulation of the microstructure of these materials subjected to different loadings, a representative volume element may be used. In this paper, three different types of crack width a = 5 μm, 10 μm, 15 μm, has been carried. The thermal residual stresses are calculated by considering a wide range of cracks of different penetrations proximity to particle of 0.1, 0.2 and 0.5 μm. regarding the distribution of the stresses along the plane of the crack and in vicinity of the particle, results show that the penetration of the crack in the matrix causes an asymmetry. The inter-distance between crack and particle plays an important role regarding the generation of residual stresses. The lower the inter-distance, the higher the internal stresses of normal residual stresses of σzz.

Structure and Properties of Aluminum Matrix Composites Reinforced by Al2O3 Particles

2008 ◽  
Vol 591-593 ◽  
pp. 188-192 ◽  
Author(s):  
Leszek Adam Dobrzański ◽  
M. Kremzer ◽  
Klaudiusz Gołombek
Keyword(s):  
Composite Materials ◽  
Matrix Material ◽  
Aluminum Matrix ◽  
Aluminum Matrix Composites ◽  
Matrix Composites ◽  
Ceramic Fibers ◽  
Pressure Infiltration ◽  
Ceramic Phase ◽  
The Matrix ◽  
Infiltration Method

The work presents the research results of modern composite materials. The matrix material was EN AC AlSi12 alloy while the reinforcement ceramic preforms, obtained through sintering process of Al2O3 Alcoa CL 2500 powder with addition of carbon fibers as pore forming agent burned out during sintering. The composites were produced with use of porous material pressure infiltration method. The main limitation of base technology is a difficulty in obtaining composite materials with volumetric participation of ceramic phase in amount not less than 20%. Obtained on the base of ceramic preforms composite materials were tested with scanning electron microscopy. Additionally, hardness and tensile test was performed for acquired materials. Achieved results indicate the possibility of producing, with use of pressure infiltration method, porous preforms composed of Al2O3 particles, new composite material with desired microstructure and properties, being a cheaper alternative for materials with base of ceramic fibers.

scholarly journals Production of Aluminum Matrix Composite Material by Active Carbon Additive

2021 ◽  
Author(s):  
Ayman M. S. EISAY ◽  
AYDIN TÜRKYILMAZ
Keyword(s):  
Composite Material ◽  
Activated Carbon ◽  
Composite Materials ◽  
Chemical Activation ◽  
Aluminum Matrix ◽  
Aluminum Matrix Composite ◽  
The Matrix ◽  
Experimental Process ◽  
Aluminum Matrix Composite Material

Abstract The effectiveness of composite materials with the addition of activated carbon produced from biomaterial with a new application on aluminum-based composite materials was investigated in this study.Activated carbon was produced from the peanut shells via the chemical activation method and the obtained activated carbon was mixed with aluminum and composite material. For the characterization of the composite material obtained, XRD and SEM-EDS optical photographs were assessed in the experimental process. According to Vickers Hardness and Dynamic Micro Hardness results, the sample with the hardness value of 2% AC added had the highest hardness value. The elastic modulus values was found to increase by 3.4 times (9.59GPa) compared to aluminum with the addition of 2% activated carbon. This increases with activated carbon quantity, and weakens the matrix structure due to weak van der waals interaction with aluminum, which reduces hardness; therefore, the best ratio of the activated carbon reinforcement to the aluminum matrix was obtained at 2% activated carbon addition.

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 Influence of Alumina Nanofibers Sintered by the Spark Plasma Method on Nickel Mechanical Properties

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 548 ◽  
Author(s):  
Leonid Agureev ◽  
Valeriy Kostikov ◽  
Zhanna Eremeeva ◽  
Svetlana Savushkina ◽  
Boris Ivanov ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Elastic Modulus ◽  
Strength Properties ◽  
Alumina Nanoparticles ◽  
Metal Powders ◽  
Wide Range ◽  
The Matrix ◽  
Spark Plasma ◽  
Average Size

The article presents the study of alumina nanoparticles’ (nanofibers) concentration effect on the strength properties of pure nickel. The samples were obtained by spark plasma sintering of previously mechanically activated metal powders. The dependence of the grain size and the relative density of compacts on the number of nanofibers was investigated. It was found that with an increase in the concentration of nanofibers, the average size of the matrix particles decreased. The effects of the nanoparticle concentration (0.01–0.1 wt.%) on the elastic modulus and tensile strength were determined for materials at 25 °C, 400 °C, and 750 °C. It was shown that with an increase in the concentration of nanofibers, a 10–40% increase in the elastic modulus and ultimate tensile strength occurred. A comparison of the mechanical properties of nickel in a wide range of temperatures, obtained in this work with materials made by various technologies, is carried out. A description of nanofibers’ mechanisms of influence on the structure and mechanical properties of nickel is given. The possible impact of impurity phases on the properties of nickel is estimated. The tendency of changes in the mechanical properties of nickel, depending on the concentration of nanofibers, is shown.

scholarly journals Estimating the number of usability problems affecting medical devices: modelling the discovery matrix

2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Vincent Vandewalle ◽  
Alexandre Caron ◽  
Coralie Delettrez ◽  
Renaud Périchon ◽  
Sylvia Pelayo ◽  
...  
Keyword(s):  
Medical Devices ◽  
Market Access ◽  
Real Life ◽  
Usability Testing ◽  
Probability Of Detection ◽  
Usability Problems ◽  
Usability Problem ◽  
Wide Range ◽  
The Matrix ◽  
Problem Detection

Abstract Background Usability testing of medical devices are mandatory for market access. The testings’ goal is to identify usability problems that could cause harm to the user or limit the device’s effectiveness. In practice, human factor engineers study participants under actual conditions of use and list the problems encountered. This results in a binary discovery matrix in which each row corresponds to a participant, and each column corresponds to a usability problem. One of the main challenges in usability testing is estimating the total number of problems, in order to assess the completeness of the discovery process. Today’s margin-based methods fit the column sums to a binomial model of problem detection. However, the discovery matrix actually observed is truncated because of undiscovered problems, which corresponds to fitting the marginal sums without the zeros. Margin-based methods fail to overcome the bias related to truncation of the matrix. The objective of the present study was to develop and test a matrix-based method for estimating the total number of usability problems. Methods The matrix-based model was based on the full discovery matrix (including unobserved columns) and not solely on a summary of the data (e.g. the margins). This model also circumvents a drawback of margin-based methods by simultaneously estimating the model’s parameters and the total number of problems. Furthermore, the matrix-based method takes account of a heterogeneous probability of detection, which reflects a real-life setting. As suggested in the usability literature, we assumed that the probability of detection had a logit-normal distribution. Results We assessed the matrix-based method’s performance in a range of settings reflecting real-life usability testing and with heterogeneous probabilities of problem detection. In our simulations, the matrix-based method improved the estimation of the number of problems (in terms of bias, consistency, and coverage probability) in a wide range of settings. We also applied our method to five real datasets from usability testing. Conclusions Estimation models (and particularly matrix-based models) are of value in estimating and monitoring the detection process during usability testing. Matrix-based models have a solid mathematical grounding and, with a view to facilitating the decision-making process for both regulators and device manufacturers, should be incorporated into current standards.

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