FE Analysis of the Control Methods Used in Crimping of Joints with Polymer Composite Cores

This paper presents results of the Finite Element analysis of crimped cylindrical joints with polymer composite cores. Initial data of the Finite Element analysis significantly affecting results of the simulation are design parameters and mechanical properties of the components. Initial interface clearance of the joint and hardening behaviour of the steel sleeve were found to have special importance. Material testing, and dimension analysis are conducted to find the parameters´ variation limits. Performed Finite Element parametric study allowed to compare quality of existing technological parameters in respect to residual strain energy of the core chosen as a measure of the load-bearing capacity. Analysis showed that extra mechanical work parameter is the most robust to variation of dimensions and mechanical properties

Damage analysis and fracture toughness evaluation in a thin woven composite laminate under static tension using infrared thermography

This work deals with the issue of damage growth in thin woven composite laminates subjected to tensile loading. The conducted tensile tests were monitored on-line with an infrared camera, and tested specimens were analysed using Scanning Electron Microscopy (SEM). Combined with SEM micrographs, observation of heat source fields enabled us to assess the damage sequence. Transverse weft cracking was confirmed to be the main damage mode and fiber breakage was the final damage leading to failure. For cracks which induce little variation of specimen stiffness, the classic “Compliance method” could not be used to compute energy release rate. Hence, we present here a new procedure based on the estimation of heat source fields to calculate the energy release rate associated with transverse weft cracking. The results are then compared to those computed with a simple 3D inverse model of the heat diffusion problem and those presented in the literature

Damage of woven composite under tensile and shear stress using infrared thermography and micrographic cuts

Infrared thermography was used to study damage developing in woven fabrics. Two different experiments were performed, a ±45° tensile test and a rail shear test. These two different types of tests show different damage scenarios, even if the shear stress/strain curves are similar. The ±45° tension test shows matrix hardening and matrix cracking whereas the rail shear test shows only matrix hardening. The infrared thermography was used to perform an energy balance, which enabled the visualization of the portion of dissipated energy caused by matrix cracking. The results showed that when the resin is subjected to pure shear, a larger amount of energy is stored by the material, whereas when the resin is subjected to hydrostatic pressure, the main part of mechanical energy is dissipated as heat

Social Origins Theory: Untapped Potential and the Test by the Pandemic Crisis

The paper examines the explanatory potential of the social origins theory advanced by L. Salamon and H. Anheier. This examination follows two tracks. The first track is a comparative investigation of the conceptual affinity between the social origins, on one hand, and the theories of welfare regimes and varieties of capitalism, on the other. We argue that the conceptual affinity between these three theories lies in the fact that they explore what could be referred to as vertical and horizontal interactions between state and market. Vertical interactions are based on the legitimate coercion by government authorities, while horizontal relations develop at the initiative of their autonomous members. The social origins approach introduces yet another essential dimension, that of civic self-organization, into the analysis of vertical and horizontal interactions embodied in state/market relationships. Similarity of underlying conceptual foundations might suggest that all three theories would generate similarly strong academic interest in reexamining their analytical tools and applying their approaches to the diversity of new social and economic realities. The literature indicates that both the welfare regimes and varieties of capitalism have generated robust academic discussions, whereas the conceptual and analytical potential of the social origins remains relatively less explored. It has become particularly evident in the context of the COVID-19 pandemic which gave rise to a number of studies that apply the frameworks of the welfare regimes and varieties of capitalism to examine cross-country differences in government social welfare policies. However, the social origins theory seems not to have generated comparably rich research testing its explanatory power in the new conditions triggered by the pandemic challenges. To address this gap, the paper follows a second track which investigates pandemic-induced transformations in nonprofit sectors of Germany, Austria, UK and USA – countries representing three “basic” nonprofit regimes immediately corresponding to Esping-Andersen’s welfare state typology: welfare partnership, social democratic and liberal. Applying the analytical lens of the social origins approach, we look at how the impact of the pandemic moved the measurable parameters of nonprofit sectors: the scope of the third sector, the volunteer share of the workforce, the extent of nonprofits’ engagement in the provision of social services, and the share of government financial support for the sector. We further look at the pandemic-induced changes in the composition of the “tool kit” employed in government-nonprofit cooperation. Thus, testing the explanatory potential of the social origins approach, we observe that responses to pandemic challenges have contributed to a degree of convergence of both liberal and social democratic nonprofit regimes with the welfare partnership pattern. However, path dependency, which is suggested by the regimes’ “moorings” embedded in the social origins approach, remains strong enough to explain the observed viability of the core features typical of “basic” nonprofit regimes in times of the pandemic crisis

Material characterization for simulation of sheet metal forming

Advanced material models from the Chaboche family are well suited to cover springback effects and strain rate sensitivity in sheet metal forming simulations. Experimental techniques (such as tension-compression tests and other tests), parameter identification, and applications to real parts will be presented together with first steps towards virtual materials testing by means of texture simulations. Materials ivestigated range from different mild and high strength steels to magnesium sheet tested at elevated temperatures