A two-stage (macro-micro) finite element analysis of composite structure is presented in this paper. A global-local (meso) modeling method is proposed in order to reduce the computational effort usually required to analyze such structures. The loading of the micro-cell is obtained from the macro model. To apply an appropriate mesh in the global model the strain energy in a beam under pure bending moments is calculated and then compared with the numerical results. The simulation of the three-point bending test of CFRP (carbon fibre reinforced polymer) is presented as an example of the use of the developed algorithm. Standard elements from the commercial FEM analysis software package Marc are used to perform the non-linear stress analysis.

The analysis of riveted structures requires a local–global approach in modelling. The local model is used to calculate the residual stress and strain fields around the rivet hole and analyse the influence of technological imperfections on the quality of the joint. The influence of the rivet with compensator on the stress distribution at the rivet hole is presented. Contact phenomena with Coulomb friction between collaborating parts of the joint and application of an elasto-plastic material model are taken into consideration

The future belongs to biodegradable epoxies. In order to improve epoxy biodegradability, it is crucial to select suitable organic additives. The additives should be selected so as to (maximally) accelerate the decomposition of crosslinked epoxies under normal environmental conditions. However, naturally, such rapid decomposition should not occur within the normal (expected) service life of a product. Consequently, it is desirable that the newly modified epoxy should exhibit at least some of the mechanical properties of the original material. Epoxies can be modified with different additives (such as inorganics with different water uptake, multiwalled carbon nanotubes, and thermoplastics) that can increase their mechanical strength but does not lead to their biodegradability. In this work, we present several mixtures of epoxy resins together with organic additives based on cellulose derivatives and modified soya oil. These additives are environmentally friendly and should increase the epoxy’s biodegradability on the one hand without deteriorating its mechanical properties on the other. This paper concentrates mainly on the question of the tensile strength of various mixtures. Herein, we present the results of uniaxial stretching tests for both modified and unmodified resin. Based on statistical analysis, two mixtures were selected for further studies, namely the investigation of durability properties.

The objective of this work is to describe part of the selecting process of a rubber-coated fabric material model. The material is used to construct an air cushion that is a carrying element of the cassette pontoon bridge unit. During operation the air cushion is permanently in contact with a metal component, fresh water and air. Therefore various interactions, such as a contact problem, flow of medium and thermodynamics can occur. The basic material model for numerical simulation was selected based on the uniaxial tensile test. The simple method was used to describe time-dependent material properties for numerical analysis, which allows computation to take a reasonable time. In order to assess the usefulness of the selected material model the impact puncture test was modelled with the same conditions and properties as in the laboratory testing machine called Instron. Moreover, an attempt of simulating the damage process is described. The energy absorbed by the material was registered during the laboratory test which was compared with the results of numerical analysis. An acceptable compatibility of the results is noticed.