Structural optimization of thin shells using finite element method

The objective of the present work was the structural optimization of thin shell structures that are subjected to stress and displacement constraints. In order to accomplish this, the structural optimization computer program DESAP1 was modified and improved. In the static analysis part of the DESAP1 computer program the torsional spring elements, which are used to analyze thin, shallow shell structures, were eliminated by modifying the membrane stiffness matrix of the triangular elements in the local coordinate system and adding a fictitious rotational stiffness matrix. This simplified the DESAP1 program input, improved the accuracy of the analysis, and saved computation time. In the optimization part of the DESAP1 program the stress ratio formula, which redesigns the thickness of each finite element of the structure, was solved by an analytical method. This scheme replaced the iterative solution that was previously used in the DESAP1 program, thus increasing the accuracy and speed of the design. The modified program was used to design a thin, cylindrical shell structure with optimum weight, and the results are reported in this paper

Towards a new MFF New priorities and their impact on Italy. CEPS Research Paper 20 February 2020

This paper analyses the outlook for regional funding under the next Multiannual Financial Framework of the EU for which the Commission has proposed new criteria. The starting point is the so-called Berlin formula, developed from a blend of national and regional indicators. In reality, the allocation for any region depends not only on the state of the region, but also heavily on the income level of the member state in which this region is located. The modifications to the Berlin formula proposed by the Commission would accentuate the importance of the national component, despite the fact that the EU cohesion policy is supposed to aim at lagging regions, not countries. Growth in Italy has been below the EU average for some time. This means that the poorer Italian regions should be entitled to a higher amount of cohesion policy funding. However, the increase one could expect on this count is limited given the modifications to Berlin formula proposed by the Commission. The application of the new formula would lead to a somewhat lower allocation for Italy overall (especially for the Mezzogiorno) for two reasons: i) Italy is still a relatively prosperous member state, ii) There are caps to the increase of cohesion policy funding to which regions can be eligible even if their relative income position has worsened a lot. Italian Universities and research institutes benefit less from EU funding than one would expect given the size of the Italian economy from competitive support for research and innovation programmes under Horizon 2020. This underperformance is not due to political decisions as the research funding of the EU is allocated strictly on scientific merit. In the area of research and innovation there is as well a strong north-south divide within the country. Creating high quality research institutions in the south might be a more promising way to use cohesion policy funds than building roads or railways. It should receive more attention and funding from national and EU policymakers

Damage quantification techniques in acoustic emission monitoring

Acoustic emission (AE) analysis is one of the several diagnostic techniques available nowadays for structural health monitoring (SHM) of engineering structures. Some of its advantages over other techniques include high sensitivity to crack growth and capability of monitoring a structure in real time. The phenomenon of rapid release of energy within a material by crack initiation or growth in form of stress waves is known as acoustic emission (AE). In AE technique, these stress waves are recorded by means of suitable sensors placed on the surface of a structure. Recorded signals are subsequently analysed to gather information about the nature of the source. By enabling early detection of crack growth, AE technique helps in planning timely retrofitting or other maintenance jobs or even replacement of the structure if required. In spite of being a promising tool, some challenges do still exist behind the successful application of AE technique. Large amount of data is generated during AE testing, hence effective data analysis is necessary, especially for long term monitoring uses. Appropriate analysis of AE data for quantification of damage level is an area that has received considerable attention. Various approaches available for damage quantification for severity assessment are discussed in this paper, with special focus on civil infrastructure such as bridges. One method called improved b-value analysis is used to analyse data collected from laboratory testing

Influence of boundary conditions and geometric imperfections on lateral–torsional buckling resistance of a pultruded FRP I-beam by FEA

Presented are results from geometric non-linear finite element analyses to examine the lateral torsional buckling (LTB) resistance of a Pultruded fibre reinforced polymer (FRP) I-beam when initial geometric imperfections associated with the LTB mode shape are introduced. A data reduction method is proposed to define the limiting buckling load and the method is used to present strength results for a range of beam slendernesses and geometric imperfections. Prior to reporting on these non-linear analyses, Eigenvalue FE analyses are used to establish the influence on resistance of changing load height or displacement boundary conditions. By comparing predictions for the beam with either FRP or steel elastic constants it is found that the former has a relatively larger effect on buckling strength with changes in load height and end warping fixity. The developed finite element modelling methodology will enable parametric studies to be performed for the development of closed form formulae that will be reliable for the design of FRP beams against LTB failure

Semi-2-interpenetrating networks of high temperature systems

A semi-2-interpenetrating network of improved qualities which is prepared by combining a linear polymer and a cross-linkable oligomer having identical repeating units is developed. Polymers have been combined in the past into interpenetrating networks in order to gain useful properties from the combination of materials. However, previous semi-interpenetrating networks have only been formed using polymers having different repeating units. This method provides a semi-2-interpenetrating network of improved strength, adhesion, and processability