135 research outputs found
Modelling low velocity impact induced damage in composite laminates
The paper presents recent progress on modelling low velocity impact induced damage in fibre reinforced composite laminates. It is important to understand the mechanisms of barely visible impact damage (BVID) and how it affects structural performance. To reduce labour intensive testing, the development of finite element (FE) techniques for simulating impact damage becomes essential and recent effort by the composites research community is reviewed in this work. The FE predicted damage initiation and propagation can be validated by Non Destructive Techniques (NDT) that gives confidence to the developed numerical damage models. A reliable damage simulation can assist the design process to optimise laminate configurations, reduce weight and improve performance of components and structures used in aircraft construction
Modelling low velocity impact induced damage in composite laminates
The paper presents recent progress on modelling low velocity impact induced damage in fibre reinforced composite laminates. It is important to understand the mechanisms of barely visible impact damage (BVID) and how it affects structural performance. To reduce labour intensive testing, the development of finite element (FE) techniques for simulating impact damage becomes essential and recent effort by the composites research community is reviewed in this work. The FE predicted damage initiation and propagation can be validated by Non Destructive Techniques (NDT) that gives confidence to the developed numerical damage models. A reliable damage simulation can assist the design process to optimise laminate configurations, reduce weight and improve performance of components and structures used in aircraft construction
Interface Cohesive Elements to Model Matrix Crack Evolution in Composite Laminates
In this paper, the transverse matrix (resin) cracking developed in multidirectional composite laminates loaded in tension was numerically investigated by a finite element (FE) model implemented in the commercially available software Abaqus/Explicit 6.10. A theoretical solution using the equivalent constraint model (ECM) of the damaged laminate developed by Soutis et al. was employed to describe matrix cracking evolution and compared to the proposed numerical approach. In the numerical model, interface cohesive elements were inserted between neighbouring finite elements that run parallel to fibre orientation in each lamina to simulate matrix cracking with the assumption of equally spaced cracks (based on experimental measurements and observations). The stress based traction-separation law was introduced to simulate initiation of matrix cracking and propagation under mixed-mode loading. The numerically predicted crack density was found to depend on the mesh size of the model and the material fracture parameters defined for the cohesive elements. Numerical predictions of matrix crack density as a function of applied stress are in a good agreement to experimentally measured and theoretically (ECM) obtained values, but some further refinement will be required in near future work
Photochemistry of Coordination Compounds of Main Group Metals. Reductive Elimination of Thallium(III) Complexes
The use of a GA to improve the postbuckling strength of stiffened composite panels susceptible to secondary instabilities
Oltre il vincolo: un nuovo approccio alla gestione dei beni storico-culturali nelle aree rurali
Lo sviluppo e la conservazione degli spazi a bassa densit\ue0 di popolazione, dei territori aperti e dei beni storico-culturali ivi presenti sono elementi imprescindibili per una corretta pianificazione territoriale, attenta alle istanze di uno sviluppo sostenibile. I problemi posti dal dibattito culturale attorno a questi temi impongono una riflessione circa il superamento di una concezione di tutela ambientale vista esclusivamente come azione vincolistica per promuovere azioni che abbiano come obiettivo la valorizzazione del territorio e delle risorse in esso ricomprese. L\u2019obiettivo principale del presente lavoro riguarda la predisposizione di un nuovo approccio valutativo multidimensionale integrato che permetta di individuare e valutare le specificit\ue0 del patrimonio storico dell\u2019ambiente costruito all\u2019interno di un\u2019area con forti valenze ambientali che ne hanno richiesto la tutela attraverso un piano ambientale. Le analisi svolte hanno consentito di individuare, alla luce del concetto di interdipendenza culturale, sociale ed economica, diverse categorie di variabili, quantitative e qualitative, sulla base delle quali effettuare la valutazione delle risorse oggetto di studio. Il riferimento \ue8 ad aspetti storico-culturali, funzionali, localizzativi e socio-economici nonch\ue9 ad aspetti relazionali e di complementarit\ue0 con il paesaggio in cui sono inseriti. In particolare, si suggeriscono le modalit\ue0 per rendere esplicito, in un\u2019area campione, il rapporto tra le problematiche della conservazione e dello sviluppo, della valorizzazione e della tutela
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