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

Long-term, Real-life, Observational Study in Treating Outpatient Ulcerative Colitis with Golimumab

Background and Aims: Several studies have found Golimumab (GOL) effective and safe in the short-term treatment of ulcerative colitis (UC), but few long-term data are currently available from real world. Our aim was to assess the long-term real-life efficacy and safety of GOL in managing UC outpatients in Italy. Methods: A retrospective multicenter study assessing consecutive UC outpatients treated with GOL for at least 3-month of follow-up was made. Primary endpoints were the induction and maintenance of remission in UC, defined as Mayo score ≤2. Several secondary endpoints, including clinical response, colectomy rate, steroid free remission and mucosal healing, were also assessed during the follow-up. Results: One hundred and seventy-eight patients were enrolled and followed up for a median (IQR) time of 9 (3-18) months (mean time follow-up: 33.1±13 months). Clinical remission was achieved in 57 (32.1%) patients: these patients continued with GOL, but only 6 patients (3.4%) were still under clinical remission with GOL at the 42nd month of follow-up. Clinical response occurred in 64 (36.4%) patients; colectomy was performed in 8 (7.8%) patients, all of them having primary failure. Steroid-free remission occurred in 23 (12.9%) patients, and mucosal healing was achieved in 29/89 (32.6%) patients. Adverse events occurred in 14 (7.9%) patients. Conclusions: Golimumab does not seem able to maintain long-term remission in UC in real life. The safety profile was good

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

Influence of Streamwise Molecular Heat Conduction on the Heat Transfer Coefficient for Liquid Metals in Turbulent Flow between Parallel Plates

The energy equation for mechanically fully developed turbulent flow between parallel plates is numerically solved taking into account the term of streamwise heat conduction. Solutions are presented for Re = 7060 and 73620, and for Pr ranging from 0.001 to 0.1. Generally the influence of the streamwise molecular conduction results in a remarkable decrease of the Nusselt number in the thermal inlet. . Copyright © 1980 by ASM

Local nusselt number at a cylinder cooled by a slot jet of water

The results of an experimental study of heat transfer from a circular cylinder to a slot jet of water are reported. In particular the trends of local Nusselt numbers versus Re and Pr are shown for three different values of the angle from the front stagnation point, θ. At θ=0° this trend is monotonically increasing with increasing Re, on the contrary at θ=90° and θ=180° the trends exhibit two irregularities in the neighborhood of Re=9.5×103 and 1.5×104 respectively. Also the local Nusselt numbers versus θ are reported for several values of Re: the heat transfer coefficient always presents a minimum for 70° < θ < 100°