Analytical solution for composite layered beam subjected to uniformly distributed load

The article presents an analytical theory for multilayered composite beams subjected to transverse uniformly distributed loads. The formulation is based on a layerwise model characterized by third-order approximation of the axial displacements and fourth-order approximation of the transverse displacements. The layerwise kinematical model is rewritten in terms of generalized variables. The beam equilibrium equations, expressed in terms of stress resultant, allow writing the boundary value governing problem. The layerwise fields are obtained by postprocessing steps. The main advantage is to ensure the accuracy level associated to the layerwise formulations preserving the computational efficiency of the equivalent-single-layer theories.     

Buckling characteristics and layup optimization of long laminated composite cylindrical shells subjected to combined loads using lamination parameters

The buckling characteristics and layup optimization of long laminated composite cylindrical shells subjected to combined loads of axial compression and torsion are examined on the basis of Flügge’s theory. In the buckling analysis of long laminated composite cylindrical shells, 12 lamination parameters are introduced and used as design variables for layup optimization. Applying a variational approach, the feasible region in the design space of the 12 lamination parameters is numerically obtained. The buckling characteristics are discussed in the design space of the 12 lamination parameters. In the layup optimization, the optimum lamination parameters for maximizing the buckling loads and the laminate configurations for realizing the optimum lamination parameters are determined by mathematical programming methods. It is found that in case of combined loads of axial compression and torsion, the optimum laminate configurations are unsymmetric.     

Flexural behaviour of UHTCC‐layered concrete composite beam subjected to static and fatigue loads

As an engineered material, ultra‐high toughness cementitious composite (UHTCC) exhibits the characteristics of pseudo strain hardening and multiple cracking under uniaxial tension. It can be applied as the reinforcing and protective material of concrete structures. In this paper, static and fatigue flexural tests were carried out on UHTCC‐layered concrete composite beams, for which UHTCC layer was used on the tension side. Under both static and fatigue loads, plane section assumption was suitable for such composite beams, and a good bond strength was achieved between the two layers. For static specimens, the UHTCC layer enhanced the ductility of the concrete layer. While under cyclic loads, because of the reinforcing effect of UHTCC, more than one crack were formed in the concrete layer, which led to a ductile deformation. Furthermore, the fatigue damage process of the composite beam was analysed.     

Effect of interfacial debonding on the failure behavior in a fiber-reinforced composite subjected to transverse tension

By using computational micromechanics, macroscopic stress–strain curves for a glass/epoxy lamina subjected to transverse tension were determined in this paper. To compute stress for given strain, a finite element model of a three-phased unit cell with the hexagonal symmetry was employed. Mixed mode debonding conditions between reinforcement and matrix were modeled by a bilinear cohesive law. A stress transfer between matrix and fiber was simulated by a inhomogeneous interphase. A detailed analysis of a debonding growth was also presented. Parametrical studies showed that a choice of values for cohesive parameters as well as debonding locations do have an influence on the macroscopic response of material. An ability of the proposed model to simulate the softening behavior of the material under transverse tension and to predict final failure was demonstrated.     

Dynamic analysis of multi-layered filament-wound composite pipes subjected to cyclic internal pressure and cyclic temperature

Based on the three-dimensional anisotropic elasticity, the stress analysis of multi-layered filament-wound composite pipes subjected to cyclic internal pressure and temperature loading is conducted in this article. The time-dependent stress, strain and deformation distributions are numerically obtained by the use of the finite difference technique. The pressure and temperature are considered to be symmetrical about the axis of the cylinder and independent of the axial coordinate. Each layer of the pipes is made of a homogeneous, anisotropic and linearly elastic material and it is assumed that the material properties do not change with increasing the temperature. The shear extension coupling is also considered because of lay-up angles. Numerical results obtained from the present model are compared with other published results and good agreement has been achieved.     

Viscowave – a new solution for viscoelastic wave propagation of layered structures subjected to an impact load

The forward models frequently adopted for use in the dynamic backcalculation of the falling weight deflectometer (FWD) data are based on the solutions that utilise discrete transforms. In this paper, a new computational algorithm, namely ViscoWave, has been developed and implemented for modelling the pavement dynamics under the FWD impact load. The primary advantage of the proposed solution over some of the existing solutions is that it uses continuous integral transforms (Laplace and Hankel transforms) that are more appropriate for the FWD time histories whose signal characteristics are transient, non-periodic and truncated. Sample runs of the ViscoWave and the validation efforts presented in this paper showed that the proposed algorithm is capable of modelling the dynamics of a layered structure with elastic or viscoelastic material with or without a halfspace, indicating the potential of ViscoWave as a forward model for dynamic backcalculation of flexible pavement properties.     

Dynamic analysis of laminated composite plates subjected to a moving oscillator by FEM

This paper presents a finite element model based on the first order shear deformation theory to investigate the dynamic behavior of laminated composite plates traversed by a moving oscillator. The oscillator model is assumed to be consisting of two nodal masses that are connected by means of a spring-damper unit. The governing equations of motion of two sub-systems are separately integrated by applying the Newmark’s time integration procedure. Then, the obtained equations are coupled and the responses of system components are calculated in each time step. The accuracy of algorithm is verified by comparing the numerical results of static, free vibration and simplified moving force problems analysis with the available exact solutions and other numerical results in the literature. Also, the effects of mass ratio, damping ratio of system components, stiffness of suspension system, velocity and eccentricity of moving oscillator on dynamic responses is parametrically studied. This algorithm can be applied to various boundary conditions, lamination schemes and fiber angels.     

Finite element analysis of thermal stresses for laminated composites in terms of a new C0-type Reddy's theory

This article proposed an accurate C⁰-type Reddy's theory including effects of the transverse normal thermal strain to study the thermal behaviors of laminated composite plates. Although transverse normal thermal strain was taken into account, displacement variables are not increased as thermal loads can be included in the generalized force vector. Based on the proposed model, an eight-node quadrilateral isoparametric element is presented, in which the interelement C⁰ continuity conditions are satisfied. Numerical results show that the proposed model can produce accurate responses of laminated composite plates under temperature loads.     

Textile reinforcement in the bed joint of basement masonry and infill walls subjected to high wind loads

The successful structural verification of basement walls under earth pressure loading with light vertical loading is often difficult. This situation is often encountered for external basement walls under terrace doors, stairs, masonry light wells, etc., where the vertical loading that is theoretically necessary is absent. This makes it impossible to resist the acting flexural forces from earth using a vertical arch model alone. In such cases the basement wall must also resist the earth pressure in a horizontal direction. However, due to the fact the bending moment capacity of unreinforced masonry parallel to the bed joint is low you have the option here of using a textile‐reinforced bed joint with longitudinal fibres of alkali‐resistant glass or carbon fibre. With an appropriately adapted textile reinforcement in the bed joints, the masonry can fulfil the requirements for load‐bearing capacity against earth pressure with a horizontal load transfer, even under a small vertical load. The same applies to infill walls subjected to high wind loads the bending moment capacities of which are also slightly parallel to and vertically to the bed joint and cannot be provably demonstrated on large infill surfaces and strong wind loads. The load‐bearing can also be increased by improving the flexural strength parallel to the bed joint. The Chair of Structural Design in the Faculty of Architecture of the Technical University (TU) Dresden was carrying out extensive numerical and experimental studies for this purpose. In the journal Mauerwerk 01/2018 [1] first findings from small trial series have already been presented. In the meantime, a series of large‐scale tests have additionally been performed to check the promising results of the small‐scale tests with respect to their real applicability. This report should provide a combined insight into the work of the concluded research project.