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Abstract: The present work deals with the failure and reliability analysis of composite pinned-joints using theoretical models based on Weibull distribution function with experimental results for a guideline of safe design strength, which are not studied yet. The purpose of this work is to study the failure and reliability analysis of pinned-joints in glass-fiber reinforced epoxy composites. The influence of specimen stacking sequences on the mean bearing strength, mean ultimate failure stress, failure displacement and bearing stiffness was investigated. Four configurations were studied: [0/90]2s, [15/−75]2s, [30/−60]2s, and [45/−45]2s. The results showed that the apparent bearing stiffness was qualitatively agreed with the predicted Young’s modulus. Specimens with [0/90]2s stacking sequence have the maximum failure displacement and ultimate failure stress compared with the other stacking sequences. On the other hand, specimens with [45/−45]2s stacking sequence have the maximum failure displacement and bearing capacity based on the first-peak criterion. Theoretical models have been developed to predict the characteristic bearing strength, lower bound bearing strength, and safe design bearing strength at different reliability levels. These models show that the penalty paid to gain high reliability bearing strength, R =0.99, in some cases, was more than 50% of the mean value. [Copyright &y& Elsevier]

Abstract: Shear strengthening of reinforced concrete (RC) elements with fibre reinforced polymer (FRP) composites is actually a research topic far to be completely solved. Existing shear strength models lead sometimes to overly non-conservative results and need to be validated with a sufficient number of experimental tests. The aim of this work is to assess some common design models for the prediction of the shear capacity of RC beams strengthened with externally bonded FRP composites. The research is based on a wide database collected from recent literature and is mainly focused on the combination of the basic codes for RC structures (without strengthening) with current models for FRP shear strengthened structures. The research significance of this work is due to the lack of information on the performance of the above models when combined with basic codes. Particular attention was dedicated on the consistency of the models for FRP strengthened structures with Eurocode 2 [12], since it assumes a method based on the truss model with variable inclination of the compressed strut. Lastly, some improvements of the model proposed by Pellegrino and Modena [41], which takes into account the interaction between steel and FRP contributions to the shear capacity, are proposed. [Copyright &y& Elsevier]

Abstract: This paper presents a two-parameter integrated Weibull model that is implemented in a finite element analysis to capture the well known “size effect” in composite materials. It can thus account for the effect of randomly distributed defects on fibre dominated tensile failure in a general loading situation. Here it is combined with cohesive interface elements to include the interaction with delamination. As a verification of the modelling method, scaled four-point bend tests from previous research were simulated. The models gave excellent results for both the strains to failure and the final failure modes and captured the observed size effect which cannot be represented by conventional progressive damage models. [Copyright &y& Elsevier]

Abstract: In this paper a new extension of the Daniels’ theory, which account for multiple modes of failure, is presented and applied to carbon nanotube (CNT) bundles. We developed a hierarchical statistical model for treating CNT twisted strands. The analysis allow us to rigorously characterize for the first time the weakest link, that is the CNT–CNT joint, in terms of Weibull size and shape parameter. [Copyright &y& Elsevier]

Abstract: Statistical continuum theory is a powerful tool for predicting the effective properties of heterogeneous materials, where the shape of the fillers is random over the representative volume element (RVE). Due to this geometrical complexity of the shape of fillers, the heterogeneous material might present some anisotropy, which can be difficult to measure experimentally. In these cases the statistical continuum theory can be used as a tool to predict the degree of anisotropy. The aim of the present work is to present an implementation method based on analytical probability functions that can be easily integrated numerically to predict the effective properties of heterogeneous materials. In this regard, the strong-contrast version of the statistical continuum theory is used to predict the effective mechanical properties of heterogeneous materials. For validation, the effective mechanical properties of porous P-311 glass are predicted using the strong-contrast approach, and compared to experimental results and to ones calculated using a differential scheme (DS) model, which is based on Eshelby’s theory of inclusion embedded in an equivalent continuum matrix. Further, to demonstrate the effectiveness of the strong-contrast approach in dealing with anisotropic materials, the effective mechanical properties of a macroscopically anisotropic heterogeneous material are predicted and compared to ones calculated using the DS model. Finally, remarks on the implementation of the strong-contrast approach are highlighted through calculations using fillers with different sizes. [Copyright &y& Elsevier]

Abstract: Precise prediction on atomic oxygen undercutting by numerical simulation technique plays an importance role for long lifetime spacecraft design. A Monte Carlo mathematical model is presented to predict the undercutting process interaction between atomic oxygen and polyimide films of spacecraft in low earth orbital degree. In the meantime, the physical undercutting processes is described by tracing transportation particle approach on the basis of statistics. Simulated results showed that undercutting profiles with breaker patterns are in good agreement with flight experimental data for 43° and 28.5° orbit angle, as well as complicated effect factors are discussed in detail. Larger atomic oxygen fluence is favorable for producing more depth and width undercutting profiles and maximum depth is always larger than maximum width. Mass loss increased with the initial impact reaction probability increasing and decreased with the thermal assimilation coefficient going down. Especially for bigger orbit angle, the difference between depth and width are reduced due to the decrement of depth and the increment of width. [Copyright &y& Elsevier]

Abstract: Polymeric composites reinforced with natural fibres have been developed in recent years, showing significant potential for various engineering applications due to their intrinsic sustainability, low cost, low weight and mechanical strength. The interfacial adhesion between natural fibres and polymeric matrices is critical to the composite performance. In order to improve the physical adhesion of polymeric composites, micro and nanoparticles have been added to synthetic fibres in the past. This work investigates the effect of silica microparticles, volume fraction of sisal and maleic anhydride on the mechanical properties of polymeric composites reinforced with unidirectional sisal natural fibres. A full factorial design (2231) was carried out to identify the effect of these factors on the responses: bulk density, apparent density, apparent porosity, water absorption, mechanical strength and modulus of elasticity. A microstructure analyses was conducted to verify the interface condition. The volume fraction of fibres, silica addition, and the interaction between silica particles and maleic anhydride additions exhibited significant effects on the tensile strength and modulus of elasticity of the composites. The microsilica addition did not affect significantly the flexural strength; while the interaction between fraction of fibres, silica particles and maleic anhydride addition played a major role not only on the flexural strength, but also on the flexural modulus. The volume fraction of sisal fibres exhibited significant effects on the bulk density, apparent density, apparent porosity and water absorption of the composites. [Copyright &y& Elsevier]

Abstract: This paper investigates the feasibility of using artificial neural networks (NNs) to predict the shear capacity of concrete members reinforced longitudinally with fibre reinforced polymer (FRP) bars, and without any shear reinforcement. An experimental database of 138 test specimens failed in shear is created and used to train and test NNs as well as to assess the accuracy of three existing shear design methods. The created NN predicted to a high level of accuracy the shear capacity of FRP reinforced concrete members. Garson index was employed to identify the relative importance of the influencing parameters on the shear capacity based on the trained NNs weightings. A parametric analysis was also conducted using the trained NN to establish the trend of the main influencing variables on the shear capacity. Many of the assumptions made by the shear design methods are predicted by the NN developed; however, few are inconsistent with the NN predictions. [Copyright &y& Elsevier]

Abstract: Homogenisation theory may play an important role in the understanding, modelling and design of multifunctional materials. A homogenisation theory for periodic and random bianisotropic electromagnetic media is presented. Starting with a formal two-scale approach we motivate an auxiliary elliptic homogenisation problem which plays a crucial role in the construction of the homogenised bianisotropic medium which is subsequently supported by rigorous mathematical arguments based on the notion of weak convergence. Comments on the potential implementation of this theory in the modelling of complex electromagnetic media are provided. [Copyright &y& Elsevier]

Abstract: As a response to the rampant increase in research activity within reliability in the past few decades, and to the lack of a conclusive framework for composite applications, this article attempts to identify the most relevant reliability topics to composite materials and provide a selective review. Available reliability assessment methods are briefly explained, referenced and compared within an unified formulation. Recent developments to confer efficiency in computing reliability in large composite structures are also highlighted. Finally, some general conclusions are derived along with an overview of future directions of research within reliability of composite materials and their influence on design and optimization. [Copyright &y& Elsevier]

Abstract: The effects of the low earth orbit environment on three types of unidirectional high-modulus carbon fiber (M40J, M55J and M60J)-reinforced composites were determined in detail. The synergistic environmental factors were the vacuum environment and thermal cycling. Cyclic thermal loading was performed in the temperature range between 120°C and −175°C for up to 2000cycles under the high-vacuum state of 1.3−3 Pa. The material responses were characterized through an assessment of the physical, thermal and mechanical property changes. It follows from the experimental results presented that the synergistic actions of the vacuum and the thermal cycling on the composite property degradation can be attributed to the formation of microvoids and interfacial sliding at the fiber–matrix interface in the early stages of cycling. The implications of these degradation processes based on the dependence of composite properties on vacuum thermal cycling are also discussed. [Copyright &y& Elsevier]

Abstract: This research deals with the prediction of compressive strength and crushing strain of FRP-confined concrete using neural networks and regression models. Basic information on neural networks and the types of neural networks most suitable for the analysis of experimental results are given. A set of experimental data, covering a large range of parameters, for the training and testing of neural networks is used. The prediction models based on neural network are presented. The influence of raw and the non-dimensional group of variables on compressive strength and crushing strain of FRP-confined concrete is studied through sensitivity analysis, which provided a basis for the development of a new regression based model. The neural networks based model gave high prediction accuracy and the results demonstrated that the use of neural networks in assessing the compressive strength and crushing strain of FRP-confined concrete is both practical and beneficial. [Copyright &y& Elsevier]

Abstract: In the recent past, experimental results of bond tests performed by several researchers on the performances of Fiber Reinforced Polymer (FRP) applied according to Near Surface Mounted (NSM) strengthening technique showed that mechanical properties of materials and surface properties of FRP reinforcement as well as the grooves geometry and the test set up can affect the bond of this strengthening system. An experimental program aimed to compare the bond behavior of different types of FRP materials applied on concrete blocks according to Externally Bonded Reinforcement (EBR) and NSM strengthening techniques has been presented and discussed in a previous paper, showing that the NSM technique could represent a sound alternative to EBR systems since it allows the FRP tensile strength to be better exploited. Herein the results of bond tests on different types of NSM reinforcement are analyzed in terms of bond–slip relationships in order to show the appropriateness of using simplified bilinear relationships. Moreover, further experimental results of bond tests available in literature and characterized by different types of bond failures have been selected and joined to those widely analyzed in this paper in order to provide an experimentally calibrated relationship predicting the maximum debonding strain in the FRP NSM reinforcement. [Copyright &y& Elsevier]

Abstract: The distribution of particles (e.g. micro and nanoinclusions, carbon nanotubes, carbon nanofibers) within a composite material plays a vital role in dictating many important constitutive properties. In this study, a general method to quantify the dispersion and agglomeration of nano-particles in composite materials has been developed. The dispersion quantity, D, is measured by the free-path spacing between particles; whereas, the agglomeration quantity, A, is measured by the particle size. In both cases, a quantifiable percentage is calculated based on the statistical probability that either the free-path spacing or particle size falls within a certain percentage above and below μ, where μ is either the mean spacing or particle size. The proposed method is used to quantify the dispersion and agglomeration of both carbon nanofibers (CNFs) and carbon nanotubes (CNTs) within aqueous solutions. [Copyright &y& Elsevier]

Abstract: The present paper is aimed at assessing analytical formulations and calibrating an accurate and reliable design formula for FRP-confined masonry columns. After a short introduction about the key issues regarding the confinement of masonry columns by means of composite wrapping, a wide experimental database is assembled in a second section of the paper. Such a database has been obtained by merging the test results presented by the authors in a companion paper with other ones available in the scientific literature. The content of the database, the nature of the specimens and the range of variation of the relevant parameters are reported in the paper. The most well-established analytical formulae for FRP-confined concrete members are summarised in the third section of the paper; their effectiveness when applied to confined masonry elements is investigated on the basis of the collected database. The very limited number of models currently available for masonry members are also reported and discussed; they generally result in inaccurate and non-conservative predictions, as they have been commonly calibrated on experimental results carried out on specific types of masonry. Finally, a general expression for a design-oriented formula is calibrated with respect to the above-mentioned experimental database. As a matter of principle, different levels of accuracy can be achieved in calibrating such an expression, depending on the number of parameters considered in its calibration: the higher the number of such parameters, the lower the expected residual error of the resulting formula. Thus, three different proposals of design formulae for FRP-confined masonry columns are reported and commented with the aim of describing their accuracy in terms of scatter, average error and distribution of the experimental-to-theoretical ratios. [Copyright &y& Elsevier]

Abstract: This paper presents a large database including results from compression tests performed on over 450 concrete cylinders externally wrapped with Fiber Reinforced Polymer materials. The collected results were first employed to perform a statistical evaluation of the FRP strain efficiency factor; in particular, the influence of the type of fiber and the strength of the unconfined concrete were considered. New relationships for estimating the compression strength of the FRP confined concrete were then developed through best-fit analyses. Finally, a procedure available in the literature was applied by the Authors for the statistical determination of the FRP confined concrete strength to use for design purposes. [Copyright &y& Elsevier]

Abstract: Experimental and theoretical studies were conducted to propose an equation for predicting the shear strength of a pseudo strain hardening cementitious composite (PSH2C) coupling beam with steel fibers, polyethylene and embedded plates. The application of these fibers in structural member has been known to improve the post-cracking tensile strength of concrete, and significantly enhances the shear strength of RC beams. It is very important to quantify the post-cracking tensile strength of fibers and the contribution of embedded plate in the PSH2C coupling beams before discussing the proposed equation to predict the shear strength of the member. In particular, the post-cracking tensile strength rely on the shape of fibers, volume fraction, aspect ratio, bond stress between fibers and matrix, and the properties of the concrete matrix. For PSH2C coupling beams with a shear span-to-depth ratio (a/d) less than 2.5, the effect of shear transfer by arch action is also taken into account. The results of 71 tests of PSH2C beams were used to evaluate existing and proposed empirical equation for shear strength. The predicted values by proposed equation were in good agreement with both test results and other test data from the literature. Finally, this paper provides background for the simplified design equation to predict the shear strength of a PSH2C coupling beam with steel fibers and polyethylene. [Copyright &y& Elsevier]

Abstract: In this study we investigated the effects of inclusion waviness and its distribution to the effective composite stiffness. Different waviness conditions were analyzed: uniform waviness with variable inclusion orientation or aspect ratio, and uniform aspect ratio with variable waviness. The inclusion waviness was found to have a greater effect on tensile moduli and shear modulus for unidirectional composites; however, if the inclusions are either randomly dispersed or partially aligned, the degree of waviness effect was smaller. The elastic moduli were also over-estimated if inclusion aspect ratio or waviness followed symmetric distributions. In addition, the waviness distribution effect was larger when larger inclusion waviness was introduced in a composite. The lack of fiber waviness distribution assumption was found to lead to inaccurate composite stiffness predictions, especially for composite with higher fiber volume fraction. We also demonstrated the inclusion waviness effects on the tensile modulus of carbon nanotube-reinforced composites. The results showed that the disparity between theoretical predictions and experimental data could be due to different inclusion waviness conditions. [ABSTRACT FROM AUTHOR]

Abstract: In probabilistic composite mechanics, uncertainty modelling may be introduced at a constituent (micro-scale), ply (meso-scale) or component (macro-scale) level. Each of these approaches has particular advantages/limitations and appropriate fusing and benchmarking is desirable in order to improve confidence in probabilistic performance estimates of composite structures. In the present study, random variable based micro and macro-scale reliability analyses are critically compared through a limit state formulation based on the analytical stress tensor components of a rectangular simply supported orthotropic FRP composite plate and the Tsai–Hill failure criterion. The study aims to promote cross-fertilisation of alternative uncertainty modelling approaches in a multi-scale analysis framework. Propagation of uncertainty from micro to macro-scale, and the corresponding influence of changes in random variability on the reliability estimates is quantified. The importance of benchmarking experimentally-based probability distributions of mechanical properties through micro-scale modelling is illustrated, and the confidence that can be placed on reliability estimates is quantified through a series of numerical examples. [Copyright &y& Elsevier]

Abstract: The European Commission project COCOMAT aimed at exploiting the large reserve of strength in composite structures through more accurate prediction of collapse. As part of the research program, curved stiffened composite panels of various designs have been manufactured and tested in compression. In the current pool of experiments it is possible to observe the scatter in results caused by manufacturing defects and material variations. In a bid to account for the scatter in design, two qualitative measures of robustness, called Robust Indices, have been derived so that effective comparisons can be made. The first measure quantifies robustness of structures with respect to their input variables while the second measure quantifies the overall robustness of a structure. [Copyright &y& Elsevier]

This study investigates the correlation between the specific energy absorption (SEA) behavior of various right-angled profiles, e.g., those with angle-, channel-, and square geometries. The behavior is also compared with that of flat plates and circular tubes. The study proposes an approach, which allows for utilizing the results obtained from a small number of profile crush tests to predict the crush properties of other profiles. The proposed approach is to separate the effect of the resistance at the profile corners from the crushing force of the profile flat segments. A generic crush property of a corner and that of a flat segment, calculated from crush-testing a few profile specimens, has been utilized to predict the crush properties of right-angled profiles with different shapes and dimensions. The predicted crush properties of numerous profiles of different shapes and sizes proved to be practically identical to those obtained experimentally. The calculated crushing SEA of the profile flat segments has also proved to be identical to that of flat plates. • Predicting the crush properties of right-angled composite profiles with different shapes from testing other profiles. • Separating the corner's resistance to tearing from the crushing force of profile flat segments. • Predicting profile properties from corner tearing resistance and crushing properties of flat segments. • Specific energy absorption of profile flat segments proved to be identical to those of flat plates. • Circular tubes show different tearing mechanisms and geometry-dependent occurrences. [ABSTRACT FROM AUTHOR]

Abstract: The response of thermoplastic AS-4/PEEK composite laminates of two lay-ups, such as cross-ply and quasi-isotropy, subjected to tension–tension (T–T) fatigue loading at elevated temperatures was investigated. It is found that the ultimate strength of cross-ply laminate is higher than that of quasi-isotropic laminate at various temperatures, so does the fatigue strength. However, the slope of normalized stress vs. cycles curves in the quasi-isotropic laminates is higher than that of the cross-ply laminates at elevated temperatures. Finally, the simple semi-empirical predictive models in statistical analysis and multiple regressions are proposed and provided for design and application purposes. [Copyright &y& Elsevier]

Abstract: This paper describes a methodology for the calibration of preliminary resistance factors for the design of externally-bonded fiber reinforced polymer (FRP) composite renewal strategies for reinforced concrete structures using the load and resistance factor design (LRFD) approach. Reinforced concrete T-beam bridge girders rehabilitated flexurally with field-manufactured, carbon fiber reinforced epoxy composites are the specific example case studied. The calibration process is briefly described and then followed in a step-by-step manner to arrive at preliminary values for resistance factors. Continued deterioration of the existing structure due to loss of steel reinforcement is considered through use of a simple corrosion model. The work described herein is largely consistent with existing specifications for new design of bridges, including the use of the load models used to calibrate the AASHTO LRFD Bridge Design Specifications. Resistance factors are calibrated to meet three possible target reliability levels, β =2.5, 3.0, and 3.5, and are found to depend on the amount of steel lost relative to the amount needed to carry the design load. Degradation of the FRP layer due to environmental exposure over time is considered as well, and a summary of the proposed design procedure is presented. [Copyright &y& Elsevier]

Abstract: The mechanical properties of newly developed aspen fiber–polypropylene composites (APC) were experimentally explored and numerically predicted at the temperatures and humidity that are typical for domestic housing applications. The mechanical properties of APCs with five different fiber-loadings were evaluated at the room temperature, 4°C, and 40°C. Environmental effects on the mechanical properties of APCS were experimentally quantified after conditioning the APCs with two different fiber-loadings in the following temperature and humidity for over 7000h: (1) hot/dry at 40°C and 30% relative humidity (RH), (2) hot/wet at 40°C and 82% RH, (3) cold/dry at 4°C and 30% RH, and (4) cold/wet at 4°C and 82% RH. The tensile moduli, flexural moduli, and the flexural strength increased as the woodfiber content increased in the composites. However, the tensile strength decreased as the fiber content increased. The tensile strength was shown to slightly improve with an addition of a coupling agent between the aspen fibers and polypropylene. The simple empirical micromechanics Halpin–Tsai model for randomly distributed short fiber reinforced composites was employed to predict the homogenized elastic moduli of APC, by optimizing the interfacial model parameter. Scanning electron microscopy (SEM) micrographs confirmed that an addition of the adhesion promoter maleated anhydride polypropylene (MAPP) between the aspen fibers and polymeric matrix improved the interfacial bonding. [Copyright &y& Elsevier]

Abstract: Although fiber reinforced polymer composites are increasingly used through the wet layup process for the rehabilitation of deteriorating and understrength concrete structures, there is very little validated information regarding performance over extended time periods. This has resulted in the use of excessively conservative factors in design in some cases, and unconservative estimates, or complete disregard of degradation effects on some characteristics, in others. In this paper two commonly used predictive approaches are used to provide estimates of long-term deterioration for a range of material characteristics which are compared to experimental data obtained over a 3years period of exposure. It is shown that although predicted durability of tensile characteristics is extremely good for thin sections used conventionally, the rates of deterioration increase significantly with increase in the number of reinforcing layers used. In addition there is deterioration of other characteristics, especially related to interlaminar and intralaminar properties, that need to be considered. It is noted that both methods are unable to accurately account for effects of initial post-cure seen in ambient cured carbon/epoxy systems, although the conventional Arrhenius predictions provide good correlation with experiments once this mechanism has ceased. A methodology that is capable of accounting for temperature variation during exposure is also outlined. The predictions are compared with safety factors prescribed by ACI-440 and TR-55 and some inherent disadvantages of such approaches is highlighted. The basis for the estimation of safety factors based on a reliability approach using Weibull parameters is presented and typical results are shown, emphasizing some weaknesses in current design methodologies in the area of FRP rehabilitation of concrete. [Copyright &y& Elsevier]

Estimating confidence lower bound for fracture strength of composites is a key concern in design and manufacture, and the Weibull distribution has been widely used for this purpose. Previous simulation-based studies presented computational tools for these bounds involving tables or parametric equations, which lack generality and may contain simulation and curve-fitting errors. An alternative approach is to present a fast and effective simulation tool that can be directly used by the end-user. Such a tool is developed in this study for estimating the bounds using the Weibull distribution based on maximum likelihood estimation. This is a more versatile approach in that it allows the user to input any desired confidence level, failure probability, and simulation-run number. The tool is demonstrated by using fracture strength data obtained from ASTM D3039 tension tests of 19 identical carbon–epoxy composite specimens. The results are compared with those obtained from previously developed approaches. [Copyright &y& Elsevier]

This study aims to assess the viability of nanocomposites in fused filament fabrication. Polylactide/organo-modified layered silicate materials have been studied in terms of structure and properties evolution through the whole manufacturing chain, and for thermomechanical optimisation. The method included the optimisation by the composite formulation and by the additive manufacturing process by experimental designs. A competition between flow thinning of the molten composite and stiffness of the input filament with the addition of filler allows an enhanced printability at intermediate loadings. The method provides an optimisation of the final parts, enabling similar or greater tensile properties, while providing better thermal stability, with additively manufactured nanocomposite materials compared to conventionally manufactured polymers. [ABSTRACT FROM AUTHOR]

Recycling of thermoplastic composites has attracted considerable attention in the recent years. Several recycling solutions include shredding scrap to centimetre-sized flakes to retain long fibres, followed by a remanufacturing step that prevents fibre breakage. Determining the exact fibre length distribution (FLD) for these routes is crucial, as it is of importance for the processibility of the material as well as the mechanical performance of the recycled parts. In this paper, novel analysis methods are introduced to calculate FLDs based on photographs of flakes. The reliability of the method and of the sampling was found to be high. The relation between flake size and FLD was studied, showing that offcut layup barely influences the FLD in comparison to flake size. The effects of shredding settings and sieving were studied, showing a strong correlation between machine parameters and FLD, whereas the offcut size was found to have no effect on FLD. [ABSTRACT FROM AUTHOR]

In this work, a design of experiments (DoE) approach was used to determine optimum laser surface treatment conditions. Aerospace structural carbon fiber reinforced composites (Torayca® T800H/3900-2) were laser treated using a pulsed laser source with a wavelength of 355 nm, nominal pulse width of 10 ps, average power up to 7 W, and spot size of approximately 20 μm. The laser power, frequency, scan speed, and number of passes (1 or 2) were varied. The adherends were characterized using a handheld water contact angle device, scanning electron microscopy (SEM), optical profilometry, and laser induced breakdown spectroscopy (LIBS). Bonded specimens were mechanically tested using a modified double cantilever beam (DCB) method. The response models obtained from the DoE indicated that surface characteristics of adherends and failure modes of bonds were most sensitive to the average laser power. Below about 200 mW, adhesive failure was observed. For laser powers greater than about 600 mW, surface resin was largely removed from the fiber bed, and the failure mode was predominantly fiber tear. Cohesive failure (∼100%) was observed for a wide range of laser parameters indicating that laser treatment can be a robust means of surface preparation. [ABSTRACT FROM AUTHOR]