Papers by Keyword: Composite Structure

Abstract: UHPC (“UHPC” will be used in the paper for UHPFRC with steel fibres) offers great potential in terms of extending the service life of structures and reducing material consumption in bridge construction. One way to achieve the economical application of UHPC is to mechanically connect optimized UHPC structures with other structural elements made of conventional materials into a single functional unit. This paper describes the development of a structural system that provides effective use of the properties of UHPC and conventional concrete. An innovative coupling element made of UHPC material was developed for the connection. During development, computational and experimental analyses were performed, including static and fatigue resistance tests of the coupling and full-scale load tests of a prototype bridge girder. The article briefly summarizes the individual parts of the research and presents its results.

Abstract: Nowadays to examine the simulation analysis of low-velocity impact impairment on composite structure to increase the impact force by using various velocities of the impactor with different boundary conditions. These composite structures are progressively used in aerospace predominant parts. In this paper, the Carbon/epoxy composite plate subjected to low-velocity impact loading of the laminate is studied. This composite structure is widely used in automobile, aerospace, marine, and construction fields due to its admirable mechanical and physical properties compared to metal structures. To ascertain intralaminar impairment commence and growth by using Hashin’s damage criterion. The simulation study was performed using ABAQUS CAE/explicit based on a modified continuous impair pattern to examine the dynamic mechanical response and damage evolution in various orientations of integrated laminate subjected to low-velocity impact. The low-velocity impact analysis has been run to understand the reaction of composite laminate by low-velocity impact. The stacking sequence of the composite structure is [0₂/+45₂/+90₂/-45₂]_s to analyze the impact force-time curve. The simulation study brought maximum impact force using impactor velocities varying from 2.5 meters/sec to 7.5 meters/sec with different boundary conditions CCCC, SSSS, SSCC, and CCSS. These boundary conditions are major changes that occur and impact force-time curve.

Abstract: In general, a steel beam is assembled with a concrete slab by shear connectors. The connection requires high stiffness and strength to secure the composite effect even in the ultimate state. Facing this need, perfobond shear connectors are attracting a great attention by virtue of its outstanding mechanical performance. However, the connector is subjected to the fully reversed cyclic stress between the compression and tension during an earthquake. Therefore, as presented in the earlier research addressing stud shear connectors, the concrete may originate cracks under the tensile stress; and eventually, the expected composite effect is not possibly performed. To address this concern, this research carried out a total of three fully reversed cyclic loading tests using the component model of perfobond shear connection. The parameters are the presence of reinforcing bars and concrete strength. In conclusion, it was found that perfobond shear connectors exhibit more stable mechanical behavior and capacity than stud shear connectors regardless of stress orientation due to a localized stress transfer mechanism that results in smaller cracks in the slab under a fully reversed cyclic loading.

Abstract: Modal analysis is a method to describe the dynamic properties of structure such as natural frequency, mode shape and damping ratio. These properties are important for design and analysis of structure in dynamic condition. MATLAB is a high-performance numerical computation and visualization software package. It provides an interactive environment with hundreds of built-in functions for technical computation, graphics, and animation. In present analysis, use of MATLAB is done for finding the free vibrational characteristics of a structure made of composite material. The study involves finding the natural frequencies of structure made of Glass-epoxy, Carbon-epoxy and Graphite fiber reinforced polyamide materials. In this case Euler’s-Bernoulli beam theory is used for analytical solution and to construct MATLAB codes. The structure considered here is a beam with fixed-free condition. The results obtained from the MATLAB are accurate comparatively, the results obtained shows that the MATLAB can be further used to write programs which involve complicated iterations and cannot be done manually. The further work can be extended for writing the programs of much more complex equations in MATLAB and obtains exact solution.

Abstract: The bullet-resistant vest (bullet proof vest) is an important accessory to absorb impact energy and stop bullets from penetrating the body. In the present work a sandwich composite structure was designed from different sequential layers of, twinning induced plastic (TWIP) steel, polypropylene – polyethylene (PP-PE) polymer and water for bullet proof vest application. Owing to the difficulty in experimentally testing materials for ballistic impact application, a finite element – smoothed particle hydrodynamic (FE-SPH) coupled simulation was applied for analyzing the impact characteristics of the proposed composite structure. Different structural layers of the composite are simulated to select the most effective thickness of steel/polymer/water layers in energy absorption and penetration prevention. The simulation results displayed that the optimum thickness of the layers are 2 mm steel/20 mm water/2 mm steel , which is able to stop a 9 mm bullet travelling at 360 m/s with less than 10 mm displacement of the inner surface of the composite. This composite is promising and has a great potential in fabrication of effective and light weight bullet proof vest with less expensive materials.

Abstract: FRP (fiber reinforced polymer material) having a high specific strength and specific modulus, good corrosion resistance and other advantages. FRP materials in civil engineering industry has been more and more popular, and gradually become a hot issue in the world. In order to take full advantage of a variety of materials and overcome the problems in the FRP structure, this paper mainly studies the composite structure of FRP and traditional materials, namely FRP-concrete composite beam structure. The mechanical parameters of FRP (mainly including CFRP and GFRP) were selected. And the stress -strain diagram of FRP materials are drawn. Through tensile tests on FRP (including CFRP and GFRP), FRP was found to belong to brittle materials. As well as the mechanical properties of FRP materials, the ultimate load analysis, the decision to use CFRP as a composite beam structural stiffness of the research materials. When considering concrete shrinkage, creep, temperature difference effect, the stiffness of composite beam meets the requirement. The deflection of FRP- concrete composite beam is verified by mechanical formula. The change of the concrete stiffness will affect the change of the structural stiffness of the FRP- concrete composite beam. As well as through an example, it is found that the concrete shrinkage and temperature can affect the change of the stiffness of the composite structure.

Abstract: A generalised approach for the modelling of arbitrary shaped deformable structures in the framework of the discrete element method is presented. Minkowski sums of polytopes and spheres are used to describe the geometry of rounded cylinders and particle facets. In the current formulation, these new elements can be deformable. Their deformation is defined by the set of positions and orientations of their nodes. The elements can be connected to form arbitrary structures, such as grids and membranes. The constitutive behaviour of such connections is defined via an elastic perfectly plastic beam model. Contacts between other not connected structures or particles are detected based on three simple primitives: spheres, cylinders and thick rounded facets. The introduction of a virtual sphere at the contact point not only allows for straightforward contact handling but as well for the use of standard contact models based on sphere–sphere interactions. Hence, there is no need for developing new contact models. The approach is implemented into the open-source framework YADE. The capability of the newly developed approach for the modelling of soil–inclusion problems is presented.

Abstract: This paper provides a comprehensive review of various methods used for skin buckling analysis in composite components. The skin buckling phenomenon is one of the governing criteria in composite design. It is a kind of contact buckling in which partial sections of skin buckle away from the filler material. In general, the problem can be modelled as a thin plate (skin) in unilateral contact with elastic medium (filler material). The theoretical analysis of contact buckling is complicated due to the nonlinearity arising from changing contact regions. To simplify the calculations, the filler material was usually modelled as a tensionless elastic foundation. The skin buckling coefficient varies in terms of the relative foundation stiffness factors. Because the Eigen-value method is not applicable to nonlinear systems, the finite element (FE) method was usually employed for post-buckling analysis, while initial buckling performance was investigated through analytical or semi-analytical methods such as rigid foundation model, infinite plate model and finite plate model. The compressive buckling and shear buckling problems for thin plates resting on tensionless foundations have been solved successfully. However, there are still urgent needs for future research on the topic. For example, the load carrying capacity of the buckling plates needs to be formulated for practical application. Complicated problems with complex loadings and/or corrugated skins need further investigation as well.

Abstract: The article presents the results and analysis of long-term monitoring of the bridge across the Odra River on the D47 freeway in the Czech Republic near Ostrava. Structural system of this bridge is formed by a continuous composite box girder with spans from 49 to 102 m. Total length of the bridge is 402 m. The bridge was equipped by strain gauges and force sensors during the construction. The monitoring has been kept on for 10 years. The measured values are compared with the results of calculations.

Abstract: Composite materials that have low weight and high strength properties are currently one of the promising materials for a vehicle’s body. However, the effect of low velocity impact on composite may cause failure through matrix cracking, fibre breakage and delamination which may reduce the structure strength. Low velocity impact can be analysed either by experimentation or numerical simulation. Numerical simulation which is also known as finite element analysis can show the degradation of the composite structure properties after an impact loading condition without doing any experimentation. Thus, in this paper, LS-DYNA is the finite element analysis software that is used to simulate a low velocity impact on composite structures.