1,721,000 research outputs found
Delamination Growth in Composite Panels Under Compressive Load
No full textIn this paper, crack growth analyses on composite panels containing embedded delaminations has been performed using the geometrically non linear FEM code B2000, based on the Total Lagrangian Formulation. The code has been improved with an effective Virtual Crack Closure Technique to evaluate Energy Release Rate and with Penalty Method to evaluate contact forces. Validation of the proposed tool has been performed with experimental and numerical data available in bibliography for Double Cantilever Beam specimens and panels with embedded delaminations
Three-Dimensional Progressive Damage Analysis of Composite Joints”, presentato alla conferenza internazionale
No full textThe laminated composites were analyzed by three-dimensional progressive damage approach. This approach is based upon geometrically non-linear finite element formulation for stress calculation. The analysis showed that the choice of the penalty parameter for contacts and the choice of the reduction factor for the degraded material properties are the key factors for the further development of composite joint
Evaluation of the effectiveness of N-Acetylcysteine (NAC) and N-acetylcysteine-cyclodextrins Multi-Composite in Pseudomonas aeruginosa biofilm formation
No full textPseudomonas aeruginosa is a gram-negative bacillus involved in biofilm production in several lung diseases. In this study, the in vitro anti-biofilm effect of both N-acetylcysteine (NAC)-a well-known antioxidant compound and GSH prodrug-and NACESOLTM-a new multicomposite based on NAC, resveratrol, and cyclodextrins-was investigated by evaluation of reduction of bacterial colonies growth. Physico-chemical analysis of NACESOLTM was performed by differential scanning calorimetry (DSC), Fourier-transform infrared (FT-IR) spectroscopy, and X-ray powder diffraction (XRPD) techniques. The anti-biofilm activity of NAC and NACESOLTM, expressed as percentage of biofilm reduction, revealed an increased biological activity of multicomposite at low concentrations. Furthermore, the NAC activity against P. aeruginosa biofilm was also studied using scanning electron microscopy (SEM) joined to the energy dispersive spectrometry (EDS) technique, which is able to evaluate the reduction of sulfur element on biofilm surface. The use of SEM-EDS highlights the biofilm amount decrease with increasing NAC concentration. This work permitted us to highlight the minimum concentration of NAC able to interact in the P. aeruginosa biofilm formation process and the promising use of a new composite based on NAC and cyclodextrins
Homogeneous, Urban Heterogeneous or Both? External Economies and Regional Manufacturing Productivity in Europe
No full textThe objective of this paper is to analyse theoretically and empirically the effects of sectoral homogeneity and urban
heterogeneity on regional manufacturing “pure” productivity differentials. Hypotheses of the existence and co-existence of the
two types of external effects are formulated and tested for the regions of 13 Western EU countries by means of panel data
spatial econometric techniques. The outcomes clearly support our conjectures and also reveal how a simply strong
manufacturing sector, i.e., not accounting for internal specialisation, may be harmful to productivity. This result, and the
existence of heterogeneous externalities, are confirmed for a sample of regions extended to Eastern European countries
Modelling Compression Behaviour of Delaminated Composite Panels
No full textIn this work, a numerical tool was developed to take into account the fundamental phenomena involved in the compressive behaviour of composite panels with through-the-width and embedded delaminations. The modified virtual crack closure technique was applied to evaluate the delamination growth phenomenon. Stable and unstable propagations were considered in our analyses; the latter required some modifications in the numerical non-linear algorithm used in the analyses. First of all, a comparison with experimental data was performed to test the effectiveness of the numerical tool; then, a sensitivity analysis was introduced to underline the influence of delaminations' position along the thickness and their growth on the compressive behaviour
"Post-buckling behavior of composite panels under compression in presence of unstable delamination"
No full textInfluence of Delamination Growth and Contact Phenomena on the Compressive Behaviour of Composite Panels
No full textA numerical analysis, providing a realistic insight on the compressive behaviour of composite panels with through-the-width delaminations, was performed by means of an in-house Finite Element Method (FEM) based code able to analyse the influence of delaminations' growth and contact phenomena on the load carrying capability of these kinds of structures. First of all a sensitivity analysis was carried out to underline the influence of delaminations' position along the thickness and their growth on panels' compressive behaviour. Then comparisons with experimental data available in bibliography were performed to test the effectiveness of new numerical techniques. Finally a panel with two delaminations was investigated to point out the need of a numerical tool able to take into account contacts between sublaminates in order to evaluate the real structure's response under compressive load
Influence of Contact Phenomena on Embedded Delamination Growth in Composites
No full textNumerical geometrically nonlinear analyses have been performed to investigate the influence of contact phenomena on multiple embedded delamination growth in composite panels under compressive load. An in-house finite element method code based on the modified virtual crack closure technique, which analyses delamination growth, combined with the penalty method approach, which takes into account contact phenomena, was used for computations. Compressed composite panels with two embedded delaminations have been investigated for various geometrical configurations with different delaminations' sizes and positions. Comparisons with a single embedded delamination model introduced in previous papers are presented. Finally a comparison between contact and no-contact approaches is shown for a significant geometrical configuration
Embedded Delamination Growth In Composite Panels Under Compressive Load
No full textIn this paper, crack growth analyses on composite panels containing embedded delaminations has been performed using a geometrically non linear FEM code, based on the total Lagrangian formulation. The code has been improved with an effective virtual crack closure technique to evaluate energy release rate and with penalty method to evaluate contact forces. Validation of the proposed tool has been performed with experimental and numerical data available in the literature for double cantilever beam (DCB) specimens. Finally, the influence of the geometrical parameters of the delamination (size and location along the thickness) on the energy release rate distribution and delamination growth stability in composite panels under compression has been analyzed
- …
