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The fibre-reinforced epoxy composite materials, thanks to their high specific strength, have found many applications in the last decades, especially in the transportation field. However, even though this great advantage allows having a lightweight and strong structure, their application is limited by many critical aspects. Some of these depend on the fact that the composite materials are prone to a large range of defects and damages if subjected to some types of loads. Such defects and damages can be very critical for composites structures, because they may be invisible and cause a significant decrease of the residual strength. In these circumstances, if a structure is not designed under a damage tolerance philosophy it might fail under an unexpected load value, also because the presence of defects can promote the arising of unexpected instability phenomena, as for example buckling under compressive loads. For this reason, one of the most critical aspects to consider during a design process is the structural behaviour of a component under compression load. In fact, fibre and matrix failures and delaminations could reduce the residual strength of a structural component and decrease the buckling load limit. So, defects and damages which could be due either to a critical phenomenon that has previously affected the structure, such as a Low Velocity Impact (LVI), or due to voids and defects caused by manufacturing and production processes, have to be taken into account during the design process. In particular, among different defects and damages, which can affect a composite material, both delamination and fibre failures are the most dangerous. In order to assess the residual strength of damaged composite structures, compression tests are usually performed on such structures. For example, compressive tests are experimentally carried out on damaged structural components, which have been affected to an LVI in a previous phase. With the aim of studying and better understanding the structural behaviour of composites panel under compressive loads, some experimental tests and the respective numerical simulations, based on finite elements theory, have been performed and presented in the paper. The compressive test is numerically reproduced by using the finite element code Abaqus®, which, thanks to its implemented algorithms, has allowed considering different failure modes. Moreover, the progressive damage of fibre reinforced composites has been modelled by using Hashin's criteria which allowed considering two different laws for damage initiation and propagation. In particular, the paper deals with structural behaviour of both undamaged and damaged aircraft panels, with omega stiffeners, made of fibre-reinforced composite materials subjected to static compression tests. A comparison between the structural behaviours of both types of panels has been performed and presented in the paper. Moreover, with numerical model validation purpose, also a correlation between numerical and experimental results has been performed and shown in the paper.

The paper deals with structural behaviour of laminated composite plates under low velocity impact loading conditions. The aim of the work is to develop numerical finite element models and simulation techniques to be implemented in a numerical procedure, which is aimed to improve designer forecasting capabilities of damaging resistance in composite structures. On the base of advanced material models and of selected failure criteria, the proposed numerical techniques can describe the damage initiation and propagation of impact damages in composite structures. A global/local finite element modeling approach has been proposed, in order to be able to develop explicit finite element analysis of the impact event, including damage initiation and propagation of both interlaminar and intralaminar damages. The same model has been analysed under quasi static compression conditions by taking into account, in a single explicit finite element analysis, both the impact and the after impact damages. For validation purpose, numerical results have been compared with data from two sessions of experimental impact tests, followed by compression after impact tests; the considered impact energy values are 50 J and 100 J respectively.

Recognizing internationalization as one of the more recently debated topics in the management field, this paper aims at investigating the influence of international R&D teams on companies’ innovativeness. More specifically, combining the transaction cost approach, the international product life cycle model, and the eclectic paradigm, an integrative research model with four associated hypotheses is proposed to study international R&D teams. Hypotheses are tested using data collected on a sample of 218 Italian companies with the aim of enriching the ongoing debate about the role of international R&D teams in sustaining companies’ innovativeness. The research shows that the number of international team projects, the number of R&D employees from foreign countries, and the number of meetings during the year for international knowledge sharing positively influence companies’ innovative outcomes. Accordingly, results emphasize the central role of knowledge contamination and collaboration for promoting companies’ innovation.

Big Data is one of the most debated topics, as its implications for innovation management and entrepreneurship development are attracting interest from researchers and practitioners. Despite the increasing interest on this topic, a relevant research question remains unsolved: what are the conditions required for the effective management of Big Data? Adopting the interpretative lens provided by Systems Thinking and Service Logic, a set of hypotheses are defined and tested through the Partial Least Squares (PLS), with reference to the 50 Big Data companies for 2017 as identified by Big Data Quarterly. The results show that several elements such as company's investment in innovation and technology and specialization of human resource positively impact on Big Data Companies' Return on Investment (ROI). Results and discussions herein enrich previous managerial debate about the domain of Big Data highlighting ‘tangible’ elements on which act for improving innovation management approaches for companies.

The research reported in this paper was aimed mainly to investigate the different NDE techniques on specimens made by a new process labeled as "pulsed infusion", very crucial for voids content under critical loading conditions. The impact load, in fact, is critical for composite laminates due to their anisotropy, in particular in extreme temperature conditions due to their brittleness. An additional and very relevant aim was to collect a large number of experimental results to supply useful information for the numerical models needed to simulate the dynamic behavior of composite laminates. At the aim to investigate the response under dynamic loads of laminates fabricated by a new vacuum assisted technology labeled as "pulsed infusion", rectangular carbon fiber composite specimens were subjected to low velocity impact tests. Experimental tests up to complete penetration and at different energy levels, were carried out by a modular falling weight tower. All the parameters related to the phenomenon, like penetration energy, maximum force and indentation depths, were used to validate existing semi-empirical and numerical models. The largely used ultra sound technique (US) was adopted to investigate the delamination together with the thermo graphic technique. The results of the measurements were compared with data obtained on the same specimens by holographic analysis (ESPI). One of the scope was to investigate the crucial internal impact damage and assess the ability of an unconventional ND system (ESPI) in giving right information about non-visual damage generated inside composite laminates subjected to dynamic loads. Moreover, some of the specimens were cut to allow the fractographic analysis. The efficiency of the above mentioned new fabrication technology was studied also comparing the results with measurements from literature on impacted autoclave cured laminates. By the comparison between the results, good agreements were found denoting the efficiency and the applicability of the new fabrication and the used NDE methods. © 2015 Elsevier Ltd. All rights reserved.

Gas storage and petroleum Companies invest every year large sums of money to prevent the formation of gas hydrates plugs in flow lines as the safety requirements and the costs related to the blocking of pipelines suggest to invest in research studies to avoid the hydrate formation or to detect its presence. Gas hydrates are aggregates where hydrocarbons gas such as methane are embedded in a crystalline cage of water molecules: they can develop abruptly and block pipelines. The nucleation of hydrates and their growth occurs when methane comes in contact with water under suitable thermodynamic conditions, such as high pressures and low temperatures. Methane hydrates induce the most relevant troubles as they form with no warning and can produce partial or even full obstructions in a pipeline thus reducing flow, increasing both back- and differential pressures. If a line section is obstructed the differential pressure across the hydrate can set the plug in motion and accelerate it quickly up to a speed approaching that of sound. In that case, the moving mass can cause serious mechanical damages at locations where the plug meets such constrictions or obstacles as valves, elbows or tees. In this paper a gas pipeline failure case due to the presence of a moving hydrate plug has been investigated by using appropriate analytical and numerical models to analyse the motion of a hydrate plug as well as its impact against the pipe wall.