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Abstract The activity of isotactic polypropylene (iPP) nucleating additives during shear flow of composite materials is still not entirely explained. In current work the sol-gel method was employed to synthesize [...]

In the companion paper, a total Lagrangian finite element (FE) model was formulated for the second order nonlinear inelastic analysis of steel-concrete composite members. This paper describes the implementation of the incremental-iterative procedure for the FE model. It has been found that using the standard tangent modulus matrix in an incremental-iterative solution procedure may cause error accumulations. These errors in turn lead to an unsafe drift from the yield surfaces, and the yield criteria may be violated. Consequently, the quadratic asymptotic rate of convergence of the Newton-Raphson method is lost. To solve this problem, a consistent tangent modulus matrix is needed in the incremental-iteration solution process, and this is described. This paper presents the implementation of the FE model and shows how to use the constitutive models in the companion paper in association with the uniaxial stress-strain relations including that for confined concrete. Some of the applications of the FE model to various problems are also shown in this paper. The comparisons between numerical and experimental results demonstrate that the FE model provides excellent numerical performance for the nonlinear inelastic analysis of steel-concrete composite members. CE Database subject headings: Beams; Columns; Composite materials; Inelastic action; Concrete; Steel; Finite element method.

A total Lagrangian finite element (FE) model has been formulated for the nonlinear inelastic analysis of both composite beams and columns. An accurate rotation matrix is used in the position vector analysis and nonlinear strain derivations. The slip between the steel and concrete components due to the flexible shear connection at their interface is considered as an independent displacement in the formulation which makes it easier to assign the corresponding proper slip conditions at the connections between composite beams and columns. The effects of nonlinearities and slip on the deformations and strains in the steel and concrete components, and so on the stress resultants (i.e., internal forces), stiffness, and strength of the composite member are thus combined together in the formulation. The constitutive models for steel and concrete in this investigation are based on the longitudinal normal stress and the shear stress induced by the slip between the steel and concrete components. Hence, these models include the effects of the slip at the interface on the von Moses yield surface, associated flow rule and isotropic hardening rule. These constitutive models can be used in association with any type of uniaxial stress-strain curves for steel and concrete, including hot-rolled or cold-formed steel, and confined or unconfined concrete. The constitutive models are expressed in terms of engineering stresses and strains. The total Lagrangian formulation is applicable for these constitutive models directly, and most convenient for the slips at the interface between the steel and concrete components. CE Database subject headings: Beams; Columns; Composite materials; Inelastic action; Concrete; Steel; Finite element method.

The effect of fiber length on the mechanical properties of extruded cement-based polyvinyl alcohol fiber composites is strongly associated with the distribution of the fibers in the material. Statistical methods from the theory of point processes can be used to describe these patterns by straightforward and easily calculated statistics. The intensity of the fibers in different parts of a sample yields a general description of the fiber pattern, but the effects of length are expressed through second-moment measures that are found to be distinct for different fiber lengths and that are strongly associated with material properties.

A corotational approach is used to analyze toroidal shells under static-dynamic loading. This approach decomposes the deformation into stretches and rigid-body rotations, examining the deformed state with respect to an orthogonal rigidly translated and rotated triad located at the point of interest on the deformed structure. The Jaumann stresses and strains are employed in the algorithm. Local and layerwise thickness stretching and shear warping functions are used to model the 3D behavior of the shell. These functions, developed through the use of the constitutive equations, enforce the continuity of stresses and displacements required at the ply interfaces and laminate surfaces. The model is validated against toroidal shell data available in the literature, and it shows good agreement.

An improved elasticity solution to the problem of buckling of orthotropic cylindrical shells subjected to external pressure is presented. The 2D axisymmetric cylindrical shell is studied (ring approximation). Specifically, in the development of the governing equations and boundary conditions for the buckling state, the solution includes the terms with the prebuckling normal strains and stresses as coefficients (i.e., the terms (mathematical expression not reproducible in ASCII) and (i.e., the terms (mathematical expression not reproducible in ASCII), which were neglected in the earlier work as being too small compared to the terms (sigma)'(sub ij) and (sigma)(super 0)(sub kk)(omega)'(sub j), respectively). The formulation results in a two-point boundary eigenvalue problem for ordinary differential equations in r, with the external pressure p as the parameter. The results show that the effect of including the normal strains and stresses is to further decrease the critical load. This decrease (versus the earlier elasticity solution without these terms) depends on the shell thickness and is generally moderate, and in no event comparable with the (quite large) decrease of the elasticity versus the shell theory prediction. This decrease depends also on the degree of orthotropy, and it is smaller for the isotropic case. Finally, a formula is derived for the critical pressure based on a first-order shear deformation formulation, and the comparison shows an improvement versus the classical shell for thick shells, but still the elasticity solution is noticeably lower than the first-order shear deformation prediction.

This paper presents an advanced nonlinear finite-element (FE) program developed for the analysis of general composite structures of steel and reinforced concrete, including composite space trusses. The elements used to represent the concrete slab and steel beam actions are described, and in particular the ability to model ribbed composite slabs of reinforced concrete on profiled steel sheeting is demonstrated. Attention is drawn to the usefulness of the layering technique in determining local stress redistributions associated with progressive through-depth cracking and yielding in the slab and steel beam elements. Concrete is represented as a nonlinear elastic isotropic material before cracking and nonlinear orthotropic thereafter, while steel is taken to be initially elastic with strain-hardening capabilities after yielding. All material models are empirical in origin. A specialized stub element with empirical nonlinear shear force-slip relationships is used at the concrete slab-steel beam interface to permit modeling of either full or partial shear connector action. Results obtained from the use of the program, including predicted crack patterns, are shown to compare very well with those from experiments on reinforced concrete slabs and steel-concrete composite structures up to failure.

This study proposes a new theoretical approach for predicting the tensile stress-strain relation of random short-fiber-reinforced cement composites showing pseudostrain hardening. This approach is grounded on the solid basis of micromechanics, which describes the pseudostrain hardening phenomenon in terms of constitutive properties of the fiber, matrix, and fiber/matrix interface. The proposed modeling requires theoretical treatment of an inelastic strain due to multiple cracking. This modeling is achieved by employing a probabilistic description of initial flaw size distribution, which should be known for predicting the stress-strain relation. This study proposes a practical method for this identification using the tensile test result of a reference composite. A comparison with the test data indicates that the proposed model is capable of reasonably reproducing the stress-strain relation of 'similar' composites. Such composites have a configuration similar to the reference configuration but different in fiber volume fraction and fiber length. Finally, the proposed theory is a potentially powerful tool for tailoring composites to satisfy targeted structural performance.

This paper describes axial compression test results of 27 concrete cylinders confined by carbon fiber reinforced polymer composite jackets. The experimental parameters include plain concrete compressive strength and the thickness of the composite jacket. It is found that the carbon fiber composite jacketing can significantly increase the compressive strength and ductility of concrete. The test results indicate that concrete strength and confinement modulus, defined as the ratio of transverse confinement stress and transverse strain, are the most influential factors affecting the stress-strain behavior of confined concrete. The failure of the confined concrete was dominated by the rapture of the jacket at an average strain much smaller than the ultimate strain obtained from tension tests of flat coupons. In order to describe the main mechanical features of the confined concrete, a simple bilinear stress-strain model is suggested based on the theory of elasticity and minimum number of empirical equations determined from the tests. The simple model is shown to compare well with test results from previous studies by other researchers.

In this study, mechanical properties of fired clay and expanded perlite aggregate mixtures have been predicted by applying the composite materials approach. Models and analytical expressions of composition and property relations recorded in literature for the modulus of elasticity and compressive and flexural strengths are summarized and results of the experimental work are given. As a conclusion, a dependable approach has been obtained in which the effects of the phases are emphasized.

The results of a detailed study of the effect of cutout on the nonlinear response of curved unstiffened panels are presented. The panels are subjected to combined temperature gradient through-the-thickness combined with pressure loading and edge shortening or edge shear. The analysis is based on a first-order, shear-deformation, Sanders-Budiansky-type shell theory with the effects of large displacements, moderate rotations, transverse shear deformation, and laminated anisotropic material behavior included. A mixed formulation is used with the fundamental unknowns consisting of the generalized displacements and the stress resultants of the panel. The nonlinear displacements, strain energy, principal strains, transverse shear stresses, transverse shear strain energy density, and their hierarchical sensitivity coefficients are evaluated. The hierarchical sensitivity coefficients measure the sensitivity of the nonlinear response to variations in the panel parameters, as well as in the material properties of the individual layers. Numerical results are presented for cylindrical panels and show the effects of variations in the loading and the size of the cutout on the global and local response quantities as well as their sensitivity to changes in the various panel, layer, and micromechanical parameters.

The solution for the stress state present in the vicinity of transverse matrix cracks within a composite laminate is typically obtained by assuming a regular crack spacing geometry for the problem and applying a shear-lag analysis. In order to explore the validity of this underlying assumption, the probability density function for the location of the next transverse matrix crack within a crack bounded region is examined. The regular crack spacing assumption is shown to be reasonable from an engineering point of view. Continuing with this assumption, a generalized shear-lag model for multilayer, off-axis laminates subjected to full in-plane loads is developed. This model is used to quantitatively evaluate the effective elastic properties of the damaged material. The results are applicable to materials such as ceramic matrix or polymer matrix unidirectional fiber systems where damage in the form of transverse matrix cracks arises.

In the case of landfills with heat generation, the long-term efficiency of composite liners at the landfill base is imperiled by desiccation and subsequent cracking of the mineral liner below the geomembrane. Downward vapor diffusion due to temperature gradients leads to desiccation unless it can be balanced by capillary rise. A numerical model (SUMMIT) of coupled transport of water, vapor, and heat in unsaturated porous media was developed to assess the landfill-specific desiccation risk of mineral liners (in terms of matric potentials). Water retention and unsaturated hydraulic conductivity of mineral liner and subsurface materials were measured. Simulations of nonisothermal lab and field experiments show that nonisothermal vapor diffusion can be up to five times higher than is physically explainable. Matric potentials in the mineral liner decrease (and thus the risk of cracking increases) with decreasing unsaturated hydraulic conductivity and water capacity, and increasing air porosity and distance to ground water. Desiccation simulations for typical landfill conditions show that the drainage layer directly beneath the mineral liner will most probably lead to cracking.

A simple mechanical model for a high-pressure hose made of ethylene-propylene rubber reinforced with two helical steel wires and a layer of fabric is analyzed. The model assumes perfect bonding between the different constituents and the torsional effect due to the right-handed helical wires is neglected. Both linear and nonlinear stress-strain relations are considered for the rubber which is assumed to be incompressible. Stresses and strains of the constituents are obtained for different internal pressures and geometrical parameters.

A micro/macromechanical approach was used to model and simulate crack initiation and crack propagation in particulate composite structures. The approach used both the micromechanical and macromechanical analyses in tandem. The micromechanical analysis was based on a simplified micromechanical model and damage mechanics at the micro-level, and the macromechanical analysis utilized the finite element method. In using these methods, crack initiation and growth in a general shape of composite structure were investigated with an efficient computational effort. It was assumed that a crack initiates and/or propagates when localized damage is saturated. As a result, the crack length was assumed to be the size of the saturated damage zone. Matrix crack initiation and propagation at circular notch tips were simulated using this approach. Modeling and simulation were also conducted for cases of nonuniform particle distribution in particulate composite structures. Predicted results showed a good agreement with the experimental data.

Composite pipes have been utilized in the petrochemical industries where corrosion resistance and light weight are important. There is a need to calculate the buckling load for the pipe under torsion which develops from the structural loadings. An analytical model of composite pipe in torsion is developed during this study. Laminated anisotropic plate theory is utilized to derive the kinematics and constitutive relations of the pipe wall laminates. Solutions are obtained by using the Ritz method with suitable boundary conditions. Good agreement is found when comparing the present results with the analytical and experimental results from previous research.

The paper presents a methodology that can be employed in numerical and analytical analyses of composite plates subjected to the action of a laser beam. The problem is related both to protection of composite components of aerospace structures from hostile high-energy laser weapons as well as to drilling holes in composites using a laser. In both cases, a three-dimensional state of stresses in the vicinity of the focal spot (the contact zone where the structure-laser beam interaction takes place) has to be evaluated. In addition, if a hostile laser locks on a structure, it is necessary to estimate changes in the structural response during and after the interaction. The paper outlines the solution of the problem of local three-dimensional stresses as well as an approach to the global response analysis. Finally, a practical problem where local damage exists in the structure as a result of a limited exposure to a laser beam is discussed. Numerical examples illustrate that even a small indentation produced by a laser can noticeably affect the natural frequencies of a composite beam.

The elasticity solutions for composite laminates in bending originally developed by Pagano are extended for Hertzian contact-type loading in this paper. Two solutions are obtained, corresponding to cylindrical bending and three-dimensional bending of a rectangular plate. Loads simulating contact with a spherical indentor are obtained by superposition of the elasticity solutions for individual terms of truncated Fourier sine series representations of Hertzian contact stresses. In this way, a benchmark for models of impact loaded plates is provided in which the loading is more representative of contact than the solutions often used for that purpose. The solutions provide insight into the interpretation of experimental data from low-velocity impact tests and are used to judge the performance of finite-element-based low-velocity impact algorithms in predicting stress under the impactor.

In this paper we present a methodology and a rigorous solution formulation for multiple crack problems in nonhomogeneous plates using the dislocation complex potential technique. The fundamental perturbation problem is investigated by establishing a system of singular integral equations, whose solution gives mixed-mode stress intensity factors [(SIFs), k] and strain energy release rate [(SERR), G]. The numerical integration of the singular integral equations is carried out by using a Lobatto type collection technique. Finite-element analysis (FEA) of the representative problem is provided for accuracy comparison. Finally, studies for two cracks located on the opposite side of the interface are presented.

Previous experimental work has shown a reduction in the effective elastic response of [[+ or -]45 [degrees]], SiC/Ti composite tubes under axial and torsional loading. There is considerable evidence of fiber/matrix de-bonding in off-axis plies and the presence of preexisting fiber cracks, extending radially from the carbon core of the SiC fiber, is also well documented. In this work, the Generalized Method of Cells (GMC) micromechanical model is used to calculate a constitutive equation for the composite material in each ply, in the presence of fiber cracks or fiber/matrix debonds. These constitutive equations are used in the exact analytical solution for the problem of an arbitrarily laminated tube under axisymmetric or torsional loading. By employing GMC in the solution to the tube problem, predictions are made as to the degree of degradation of the elastic response of these tubes due to partial or full debonding of the fiber/matrix interface or preexisting fiber cracks or a combination of both. These theoretical predictions are compared to experimental results.

An experimental investigation was conducted to determine the flexural characteristics of advanced composite grid reinforced-concrete structures. Concrete beams reinforced with orthogonal grids composed of corrosion-resistant fiber-reinforced polymer composites (carbon/vinyl-ester and fiberglass/vinyl-ester) were compared to standard steel-reinforced beams. Flexure tests were performed on 26 0.762 mm (30 in.) long beams with a 0.1524 mm (6 in.) square cross section under four-point bending. The various test configurations incorporated #3 steel-reinforcing bars and/or composite grids with 0.0508 or 0.1016 mm (2 or 4 in.) spacing. The flexural strength, stiffness, and failure characteristics were evaluated by monitoring the load, deflection, and strain coupled with visual observation. The present study provides insight into the relevant load-transfer mechanisms, geometric issues, and dependence on material properties. The results show that the behavior of composite grid reinforced beams can be predicted with the same accuracy as traditional steel reinforcement enabling a simple, straightforward extension of existing design criteria. Composite grids designed and fabricated to have the same axial rigidity as steel rebar result in equal deflections for equal loads and significantly higher ultimate strengths, with reduced toughness due to the linear elastic characteristics of the reinforcement materials.

An analytical model for laminated composite strips exhibiting extension-twist coupling is presented. The analysis is developed first for fiat laminates and subsequently extended to include finite pretwist. The displacement field is developed in three steps, each accounting for a kinematic contribution. A finite rigid-body twisting rotation is considered first. This is subsequently modified to include Saint-Venant's type warping where the transverse normal and out-of-plane shear strains are neglected. Finally, inplane extension, shear, bending, and twisting curvatures are accounted for by superimposing a classical-type small-displacement field. Closed-form expressions relating applied extension to twisting rotation are obtained and the contribution of axial force to the twisting moment is isolated. Three approximate models are derived and the influence of the free-edge conditions and Saint-Venant's assumptions are assessed. Based on this assessment, a simple two-parameter model accounting for the axial force contribution to the twisting moment is proposed. Comparisons of analytical predictions with a finite-element simulations for both flat and pretwisted laminates illustrate the accuracy of the developed models. A set of pretwisted laminated composite strips made of a graphite/cyanate material system is manufactured and tested. A custom-made apparatus designed to allow the laminate to twist freely under axial loading is used to measure the twist angle associated with applied axial force. Test results depict the nonlinear axial force-twist behavior and the analytical predictions are in close agreement with test data.

In this paper, a set of simple formulations is derived to predict the instability critical loads of orthotropic composite tubes under pure bending. The formulations are based on the assumption that the instability of an orthotropic composite tube under pure bending is due to the ovalization of its cross section. For the static instability case, the ovalization increases steadily as the curvature increases, which results in a reduction in the bending rigidity of the tube. The interaction of longitudinal bending and cross-section ovalization causes the tube to have a limit load instability. For the dynamic instability case, the instability of the tube is due to the interaction of two vibrations, one is the longitudinal bending of the tube as a beam, the other is the circumferential bending of the tube as a thin-walled shell.

The presence of small amounts of residual void space (on the order of one percent by volume) is sufficient to make estimates of composite elastic constants (obtained while ignoring this porosity) violate the Hashin-Shtrikman bounds in many cases. Experimental values falling below the incorrectly estimated lower bound is the normal direction of violation, but erroneous neglect of porosity in 'pure' samples can also lead to experimental values rising above the incorrectly computed upper bound. Examples are presented to illustrate the nature of the error and methods of correcting it for data on composite ceramics. The result is improved agreement between the Hashin-Shtrikman bounds, effective medium theory estimates, and experimental data.

In order to form long fiber-reinforced plastic sheets into angled parts, a new process called the Laminate-Bending Process was recently developed. The process consists of preforming a prepreg into semi-cured stable shapes having various sharp bending radii, followed by laminating the performs into a fully cured thick angle product having high strength and rigidity. 90 [degrees] V-angled product of five lay-ups of preform was test fabricated under various preforming and laminating conditions by using a continuous glass fiber reinforced epoxy resin, and it was confirmed to be excellent in delamination resistance and specific strength. Also, the process is quite practical in productivity, handling, and applicability to other advanced composite materials, and it can expand the use of such brittle materials for wider applications.

A new calculation procedure is described that provides an alternative to full-scale testing for composite slabs with ribbed decking used in buildings. The procedure consists of combining shear-bond test results with a numerical analysis to predict the behavior and strength of composite slabs. It may be used to analyze either single spans or multiple spans. The procedure incorporates certain simplifications and assumptions that allow for a reasonable yet conservative prediction of both behavior and strength. In particular, chemical bonding between the concrete slab and decking and concrete tension behavior are ignored because they are brittle in nature. Advantages of using this procedure rather than full-scale test results are versatility and reduced cost, the estimation of deformations at working loads, the inclusion of additional variables such as end anchorage (over the end supports), additional positive moment reinforcement (in the span), and reinforcement in negative moment regions (near interior supports). This calculation procedure may also be used for the development of new decking and to improve the performance of slabs with existing decking. Examples of calculations are presented for single-span composite slabs.

The results of selected tests on full-scale one-way single and continuous span composite slabs with ribbed decking are presented. Variables investigated in these tests include the number of spans, the presence of embossments in the decking, end anchorage (both welded and shot-fired shear connectors), and negative moment reinforcement near interior supports. An example comparison is given between a standard test and the calculation procedure combining shear-bond test results with a finite element analysis (the calculation procedure was presented in part I). The importance of composite slab internal moment resistances as a function of the applied load is examined. For a composite slab, three internal moment resistance elements are of importance: the decking, concrete slab (including additional reinforcement), and the interaction between decking and concrete slab. Parametric analyses based upon the calculation procedure predictions are performed for three decking geometries using limiting slenderness ratios. Decking types were chosen to represent a wide range of shear bond connection characteristics. Slenderness ratio is defined as the span length divided by the total composite slab depth. The effects of eleven parameters are investigated for each decking and slenderness. Effects studied include the load-carrying capacity at service deflection limits (L/250), ultimate deflection limits (L/50), and maximum load-carrying capacity.

Shape memory alloy hybrid composite materials have demonstrated numerous control capabilities. One such capability is the controlled bending of structures. In this paper the response of a cantilevered beam to an internal actuator is examined. The modeling of the compressive force exerted by the induced strain of the actuator on the beam is discussed. The results obtained from treating the force as an external follower force are presented. The response to an internal force such as exerted by an internal shape memory alloy actuator is quite different from that produced by loads due to sources external to the beam. Contrary to normal expectations such an internal force although compressive does not produce any buckling tendencies or any other instabilities in the beam. This principle which is already in use in the design of civil engineering structures is discussed in detail. If the actuators are embedded off of the neutral axis, then due to the eccentricity the beam bends, but again without any buckling tendency. The experimental results obtained for this configuration are also presented., Shape memory alloy (SMA) hybrid composites are found to be effective in structural control. The response of a cantilevered beam to an internal SMA strain induced actuator is investigated. A model of the force exerted by the actuator on the beam is developed. The effects of the internal force differs from those produced by external loads because this does not cause buckling in the beam. The application of the SMA actuator for the bending control of a fiberglass beam is also presented.

Effects of an axial defect in the composiTe of hoop-wrapped steel and aluminum cylinders on the hoop stress as well as on the bulging of the liners were investigated through the numerical and experimental stress analysis. Comparison with the experimental results (reported in reference [5]) suggests that relative fatigue performance of the cylinders, containing damages to the composite wrapping, can be assessed without conducting prototype tests., Steel and aluminum hoop-wrapped cylinders were wrapped with an E-glass/polyester resin composite. Each composite specimen had different midsection external cuts to determine their effects on cylinder performance. Stress on the steel hoop-wrapped cylinder was determined by nonlinear finite element stress analysis, while stress on the aluminum hoop-wrapped cylinder was derived from linear finite element and experimental stress analysis. Analysis methods used were proven to be accurate in measuring the effects of damaged composites on cylinder performance.

Byline: W.A. Lees The relevant characteristics of both composites and metals are discussed with reference to their forming good joints with themselves and each other. The relationship between these adherends and a variety of suitable adhesive types is also reviewed with particular reference to the ductility, brittleness and toughness of the various adhesives and their individual capacity to cope with brittle and possibly contaminated surfaces. The theoretical aspects of joint stress distribution are presented as a background to the design of good load bearing joints. The paper concludes with the innovative suggestion that toughened adhesives may be used as laminating resins where joints are to be very heavily loaded.

Byline: M. Marchetti, P. Testa, F.R. Torrisi An apparatus has been designed for measuring thermal conductivity and thermal resistance in vacuum as a function of the applied pressure and of the average temperature at the interface. Results are reported concerning metals such as stainless steel, aluminium and copper, and composite materials such as glass and carbon fibre-epoxy for space applications. The pressure ranged from 0 to 28 x l0.SUP.6 Pa and the temperature from 30-90[degrees]C. As expected, thermal resistance was seen to decrease with increasing pressure. Resulting uncertainties turn out to be rather high (between 10 and 40%) but still compatible with normal design requirements

Byline: V.M. Karbhari, D.J. Wilkins Composites decisions are highly coupled between materials, configuration and processes. Faced with a global economy and increasing competitiveness, the issue of high cost, product and robustness and long lead times associated with product development are emerging in the forefront of challenges facing the composites industry. The successful development of a product is dependent of the efficiency of the early decisions made in order to satisfy not only the technical requirements but also those within the larger picture of consumer economics and customer satisfaction. The focus of this paper is emphasizing metrics of comparison aids in concept selection process, and the integration of disciplines of design, manufacturing, and economics in the composites product development process.

Byline: D.J. Wilkins, V.M. Karbhari Faced with increasing global competitiveness, the issues of high costs, product robustness, and long lead times associated with product development are emerging in forefront of the problems facing American industry. It is increasingly clear that a significant (70-80%) percentage of system life cycle costs are committed during the phase of concept development and this is of special significance in composites were design decisions are highly coupled. The continued growth of composites is thus dependant on both development of low-cost fabrication technologies and adoption of the philosophy of concurrent engineering. It is essential that the early decisions are made based on the integration of all phases of product development. In this paper we discuss the need for concurrent engineering methodology for composites, and present framework for such an approach.

Byline: K. Takao, H. Ogishi, H. Kimura, T. Ichida Effects of resin types and their silica contents were studied on corrosion behaviour of organic composite coated steel sheets. The following results were obtained. (1) High corrosion resistance of organic composite coated steel sheets is brought by preservation of corrosion products on the coating. (2) Types of resin and contents of silica strongly affect the corrosion resistance by changing the kind of corrosion products developed on organic composite coatings. Coating with hydrophilic resin shows good resistance with protective ZnC1.SUB.2.4Zn(OH).SUB.2 formation. However, coating with hydrophobic resin forms ZnO which retards the corrosion resistance.

Byline: M. Autio, H. Parviainen, A. Pramila In the present study the reliability of FEM in analysing composite structures has been considered. The results given by composite elements of commercial FEM-programs have been compared with reference solutions in several plate cases. The accuracy, which can be achieved in analysing real structures by FEM, has been studied by comparing results of the FEM-model with measured results. Usually errors of results given by FEM-programs were less than 10%. However, in some cases even using dense mesh the error was about 25%. The difference between FEM-results and measured results was about 20%.

Byline: Lingsen Wang Graphite yarn or Nicalon Sic yarn reinforced 7740 borosilicate composites were produced by hot-pressing the lay-up infiltrated unitapes at the temperature of 1200[degrees]C under the pressure of 6.7 MPa for 1 hr. in the atmosphere of nitrogen. The flexure strength (σ.SUB.2) and the impact toughness (α.SUB.κ) of C/7740 composite reached respectively to 792 MPa and 31 KJm.SUP.−2. The σ.SUB.2 and fracture toughness (Klc) for SiC/7740 composite were 780 MPa and 16.3 MPa m.SUP.−1/2 respectively. It was discovered that σ.SUB.2, .SUB.κ and Klc all had a maximum value with the volume fraction of fibre (Vf) increasing. The best value of Vf was about 40-45%. It was proved that σ.SUB.2 was fit well in to the Weibull Distribution as well as the Normal Distribution The interface bonding strength (τ) of SiC/7740 composite was measured successfully by Marshall Indentation Method. The effect of heat-exposing time (t) of fibre in air at 600[degrees]C on T and the relationship between τ and Klc were also dealed with. It was also discovered that T increased, but Klc decreased with τ prolonging in the range of present experiment. The mechanism of hot-pressing densification and other problems were also touched with.

Byline: Kathrin Heinrich, Klaus-Dieter Lietzmann Materials are subject to complex, mechanical, thermal, chemical and tribulogic stresses according to their fields of application. Therefore the properties of materials and components have to meet specific requirements. With regard to costs it makes sense to develop the material properties for a special part only to the degree that is required for the very case of application. Composites, e.g. with a relatively cheap base material and sufficient strength but with a highly wear-resistant surface layer fit for reworking or a corrossion-resistant surface coating can be favourably used for several industrial applications. Such composites can be produced from powder or molten material variants by hot isostatic pressing. The basic technique is reported, and material properties attain able for a steel-nickel base material composite as well as possible fields of application are shown.

Byline: Vistas P. Karbhari, Scott K. Jones The realisation of products from composite materials has long been recognized as an engineering challenge. Traditional methods of assigning costs to products during manufacture or predicting costs during design involve the use of accounting methods largely rooted in the role of external reporting. Accordingly the cost information available to design teams was of limited value. In an effort to provide more timely and useful cost information to managers, new methods of viewing product cost are being developed, namely activity-based costing (ABC), and its extensions, activity based management (ABM). These evolving methods of identifying and controlling manufacturing cost give composite design teams a tool for understanding product cost during the initial identification of concepts, and production management teams an effective method of controlling production costs. They are highly suitable for the use in concurrent engineering environment and are in fact essential to the efficient functioning of rapid product development teams. Explicit attention to the application, customer preferences, and value-in-use of the product provides the design team with notion of how much a particular performance characteristic is valued by the customer. In this paper we discuss how the strategy is emphasized by ABM focuses on managing costs in composites design and manufacture while further differentiating the product through increased performance. Emphasis is put on the use of ABC as a means of ensuring the process modification and development is conducted at the appropriate product development stages.

Byline: S. Maschio, O. Sbaizero, S. Meriani In this investigation a series of Al.SUB.2O.SUB.3-ZrO.SUB.2, composites materials were prepared using unstabilised ZrO.SUB.2 or different amount of either Y.SUB.2O.SUB.3 or CeO.SUB.2 for stabilising the ZrO.SUB.2 in its metastable tetragonal form. The mechanical properties (hardness, bend strength and toughness) were measured and the influence of the different micro structure obtained as well as the role of phase transformation and micro cracks has been assessed.

Byline: Fumiko Sugiyama, Kinya Ogawa, Toshihiko Nishida The shear distributions of fibre-bonded ceramic composite were investigated using finite element analysis. The effect of notch distances on the shear stress distributions in a double notch shear (DNS) specimen was investigated under static and impact loading conditions. The stress concentration near the notch roots became larger as the notch distance increased. The effects of variations in the notch distances upon the shear strength of fibre bonded ceramics (FBC) and carbon-fibre reinforced silicon nitride (CFRSN) were experimentally investigated with static and impact tests. The shear strength decreased with an increase of the notch distance for both the static and impact tests, except that the notch distance was too small. The impact shear strength was larger than the static one regardless of notch distance. The shear strength evaluated by a DNS test was smaller than that obtained from a short beam bending (SBB) test.

Byline: C.B. Wang, Q. Shen, L.M. Zhang A W-Mo-Ti system flier-plate material with graded wave impedance, which can realise quasi-isentropic compression and has important application in dynamic high-pressure technology, was prepared. The impedance distribution of the flier-plate was designed via numerical simulation. Then, W-Mo and Mo-Ti composites with gradually-changed compositions were stacked and sintered at 1473K-30MPa-10min to prepare the W-Mo-Ti system flier-plate material. The wave impedance of the flier-plate changed quasi-continuously along the thickness direction in a parabolic distribution form. By using the W-Mo-Ti flier-plate, a quasi-isentropic compression wave with a slowly-rising front was obtained.

Byline: T. Ramesh, M. Prabhakar, R. Narayanasamy Workability refers to the relative ease with which a material can be shaped through plastic deformation. In the near future, it is expected that the aluminium-based-metal-matrix composite materials will replace the heavy alloys as well as the steel applications. An attempt is made to investigate an important property called workability of aluminium-based-metal-matrix composites namely Al-SiC. Cold upsetting tests on aluminium with varying percent content of Silicon carbide metal matrix composite have been conducted and the workability behaviour of the aforesaid MMC has been investigated.

Byline: K. Mohamed Kaleemulla, B. Siddeswarappa Hybrid composite materials reinforced with woven fabrics are becoming increasingly popular for various structural applications in the automotive, aerospace, and other industrial sectors; particularly in thin walled structures. The present investigation concentrates on fabric-reinforced hybrid composite laminates with seven different volume fractions of the constituent materials; epoxy resin, plain-woven S2 glass fabric, and textile satin fabric. Fracture toughness of a material has immense importance in the determination of the resistance of the material to crack propagation. In this paper, an experimental investigation has been carried out on the tensile strength and fracture toughness of woven fabric reinforced hybrid composites with 0[degrees]/90[degrees] orientation for six different notch configurations. Experimentation and specimen dimensions are in accordance with ASTM D5766 standards. The fracture toughness has been found to increase continuously with increased volume of glass fabric, whereas the fracture toughness has been found to be less dependent of notch size upto certain limit.

Byline: S.N.R. Choudhury, A. Edwards, M. Provatas The focus of the present study is to understand the effect of injection moulding process parameters on the surface finish of PC/ASA (polycarbonate/acrylonitrile-styrene acrylate) moulded parts through the analysis of both the bulk and surface chemical behaviours. Thermogravimetric analysis (TGA) provided information on material composition, thermal stability and decompositional behaviour, while Photoacoustic Fourier Transform Infrared Spectroscopy (PA-FTIR) was used to identify the effect of injection moulding on the chemical structure of the composite material. Microscopic analysis of surface defects was accomplished via Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). Bulk analysis by TGA showed that the thermal stability of parts was lower when manufactured at extreme material temperature, injection speed and pack pressure. Surface chemical structure was found unchanged by PA-FTIR while SEM showed the surface topography of a defect known as 'pearlescence' often present on grained parts. AFM successfully visualised the melt flow pattern and how it related to the surface finish on the moulded plaques.

Byline: David Attwood, Jonathan Hodgkin, James Mardel, Healther St John The aim of the project that is described in this paper is to develop low-cost chemical and physico-chemical methods of testing and analysis of new composite materials. This will enable the aerospace industry to predict aspects of the lifetimes of composite aerospace parts without the standard, but very expensive, mechanical testing regimes normally required. The initial section of the project has been designed to build up an under-standing of what are the environmental conditions seen by materials on modern aircraft and which of these are critical to the determination of composite lifetimes. Preliminary accelerated testing trials have shown which types of chemical analyses give the most relevant information. It has also been shown that extensive calibration of equipment and careful experimental design are required, especially when the testing conditions get closer to the 'in service' environments. Results of analyses from some actual aerospace samples have also been carried out for comparison purposes.

This project was conducted to evaluate the performance and leaching of controlled low strength materials (CLSM) incorporating fly ash and foundry sand. Two different CLSM (or flowable slurry) reference mixtures (equivalent to available production CLSM mixtures) were proportioned for unconfined compressive strength levels in the range of 0.3-0.7 MPa (50-100 psi), at 28 days, using two sources of ASTM Class F fly ash. For each reference mixture, other mixtures were proportioned using two sources of foundry sand (molten metal-casting mold sand) as a replacement for fly ash in the range of 30-85%. The ingredients of the slurry mixtures--fly ash, clean foundry sand, and used foundry sand--were tested for their physical and chemical properties and their leachate characteristics. Portland cement used as the primary binder was also tested for its properties. All CLSM mixtures made with and without foundry sand were evaluated for settlement, setting and hardening characteristics, compressive strength, permeability, and leachate characteristics. The leachate results of these CLSM-making materials were below the enforcement standards (ES) of the Wisconsin Department of Natural Resources (WDNR) ground-water quality standards (GWQS). They also met practically all the parameters of the drinking water standards. A number of CLSM mixtures incorporating fly ash and foundry sand are recommended for construction applications.