Multi-scale modelling of strongly heterogeneous 3D composite structures using spatial Voronoi tessellation

Abstract3D composite materials are characterized by complex internal yarn architectures, leading to complex deformation and failure development mechanisms. Net-shaped preforms, which are originally periodic in nature, lose their periodicity when the fabric is draped, deformed on a tool, and consolidated to create geometrically complex composite components. As a result, the internal yarn architecture, which dominates the mechanical behaviour, becomes dependent on the structural geometry. Hence, predicting the mechanical behaviour of 3D composites requires an accurate representation of the yarn architecture within structural scale models. When applied to 3D composites, conventional finite element modelling techniques are limited to either homogenised properties at the structural scale, or the unit cell scale for a more detailed material property definition. Consequently, these models fail to capture the complex phenomena occurring across multiple length scales and their effects on a 3D composite’s mechanical response. Here a multi-scale modelling approach based on a 3D spatial Voronoi tessellation is proposed. The model creates an intermediate length scale suitable for homogenisation to deal with the non-periodic nature of the final material. Information is passed between the different length scales to allow for the effect of the structural geometry to be taken into account on the smaller scales. The stiffness and surface strain predictions from the proposed model have been found to be in good agreement with experimental results.The proposed modelling framework has been used to gain important insight into the behaviour of this category of materials. It has been observed that the strain and stress distributions are strongly dependent on the internal yarn architecture and consequently on the final component geometry. Even for simple coupon tests, the internal architecture and geometric effects dominate the mechanical response. Consequently, the behaviour of 3D woven composites should be considered to be a structure specific response rather than generic homogenised material properties

“BAM”: a collaborative R&D project for the development of a simulation based solution for the design and manufacture of 3D woven composites

Breakthrough Aerospace Materials (BAM) is a collaborative R&D project based in the UK [1]; led by industry and co-funded by the British Government via the Innovate-UK under its Aerospace Technology Institute (ATI) R&T Programme. The overall objective of BAM is to develop a complete process that will enable aerospace industry (and others) to design and manufacture complex shaped components using 3D woven composites. This material offers great advantages particularly for producing lightweight structures with high resistance to impact loading and damage - yet, there is still no evidence of it been widely adopted by industry! It is agreed that one of the major reasons behind slow adoption of the 3D woven composites by industry is the lack of industrial simulation tools that can be used effectively by design and analysis engineers. A consortium consisting of 12 partners, involving 9 from industry and 3 from academia, was set up to work towards this goal over a period of three years. As it is less than a year since the kick-off of the project, this paper will mainly introduce the general approach for now - leaving the full demonstration of applying the developed technologies on industrial cases for follow up publications. However, a few independent illustration examples are still presented - while elaborating on the current status of development at various steps in the process and its associated challenges. The paper also aims to highlight the interdependence between industrial and academic partners for their success in pushing the required technology up the TRL (Technology Readiness Level) scale. Two leading CAE software developers (ESI Group and MSC Software) are involved in BAM, and both are working on developing their own strategy to tackle the problem. The paper will elaborate on the approach adopted by ESI in particular, which is aligned with its global strategy for providing virtual end-to-end solution for composites product development

Modelling process induced deformations in 0/90 non-crimp fabrics at the meso-scale

The manufacture of non-crimp fabric composites typically requires the forming and consolidation of the reinforcement material. During this process the material is subjected to complex loading where the coupling of tensile, bending, shear and compressive forces result in deformations to the internal architecture of the textile. To determine the extent of these deformations a numerical modelling method has been developed to capture the kinematic behaviour of non-crimp fabric textiles. This method focuses on capturing the interactions between the fibrous tows and the stitch yarns which bind the tows together. Through modelling at a level of detail in which the meso-scale interactions are explicitly present, the macro-scale behaviour of the material proceeds naturally within the model, negating any requirement for detailed characterisation of the physical material. This also enables a detailed description of the internal architecture of the deformed fabric to be extracted for analysis or further modelling. The present study explores the method's ability to capture both local and global deformations which occur in non-crimp fabrics, specifically to capture the onset of deformations that appear due to tow-stitch interactions and the forming and compaction of multiple layers. Comparison with experimental results show good agreement for both meso-scale deformations, resulting from multi-layer compaction, and global in-plane shear deformations induced through forming over complex tooling.</p

Investigation of competitive adsorption and desorption of heavy metals from aqueous solution using raw rock: Characterization kinetic, isotherm, and thermodynamic

Heavy metals are the most dangerous inorganic pollutants Due to their bioaccumulation and their nonbiodegradability, for this, several studies have focused on the recovery of these metals from water using different techniques. In this context, our study consists of evaluating an efficient and eco-friendly pathway of competitive recovery of heavy metals (Cd, Cr and As) from aqueous solutions by adsorption using raw rock. This adsorbent was characterized before and after the adsorption process by several techniques. The multi-metals adsorption process in the batch mode was undertaken to evaluate the effect of adsorbent mass, contact time, pH, Temperature, and initial heavy metals concentration. The kinetic data were analyzed using the pseudo-first-order, pseudo-second-order and intra-particle diffusion kinetic models. According to the modeling of the experimental results, the adsorption kinetics of heavy metals were adapted to the pseudo-second-order model. The adsorption isotherms were evaluated by the Langmuir and Freundlich isotherm models. The experimental isotherm data of heavy metals were better fitted with the Langmuir model rather than Freundlich isotherm models. The maximum experimental adsorption capacities (Qmax) predicted by the Langmuir model are 15.23 mg/g for Cd (II), 17.54 mg/g for Cr (VI) and 16.36 mg/g for As (III). The values of thermodynamic parameters revealed that the heavy metals adsorption was exothermic, favorable, and spontaneous in nature. The desorption process of heavy metals showed that this raw rock had excellent recycling capacity. Based on the results, these untreated clays can be used as inexpensive and environmentally friendly adsorbents to treat water contaminated by heavy metals

CALIBRATING MACROSCALE MODELS OF 3D-WOVEN COMPOSITES: COMPLEMENTING EXPERIMENTAL TESTING WITH HIGH FIDELITY MESOSCALE MODELS

Composites with 3D-woven reinforcement could help fill a growing need for lightweight materials with improved material integrity and out-of-plane performance. Developing efficient computational tools to predict their behaviour, however, is key to facilitating their widespread adoption in various industrial applications. Macroscale models are one such tool. They consider an approach where the material model is homogeneous and anisotropic. While macroscale models are computationally efficient, they also require large scale, complex and time consuming experimental testing campaigns to characterise the material response. One promising avenue that is explored in this work, is the development of a characterisation test matrix, in which material data is acquired through a combination of experimental testing and simulation of a high fidelity mesoscale representative volume element. In this collaborative project, both experimental testing and mesoscale simulations are carried out in order to calibrate a macroscale model for 3D-woven composites. The results are validated against off-axis experimental tensile tests, as well as multiaxial load scenarios applied to the mesoscale representative volume element

Efficient Synthesis and X-ray Structure of [1,2,4]Triazolo[4,3-a]pyridines via Oxidative Cyclization Using N-Chlorosuccinimide (NCS)

Triazolopyridines are a family of compounds that, owing to their biological activity, have many pharmaceutical applications. In this study, 3-(pyridine-4-yl)-[1,2,4]triazolo[4,3-a]pyridine and 6-bromo-3-(pyridine-4-yl)-[1,2,4]triazolo[4,3-a]pyridine were synthesized by using the chlorinated agent NCS for hydrazones under very mild conditions. The characterization of these compounds was achieved by 1H NMR, 13C NMR, FTIR, MS and X-ray diffraction. The compound 3-(pyridine-4-yl)-[1,2,4]triazolo[4,3-a]pyridine was crystallized in the monoclinic space group P 21/c with a = 15.1413(12), b = 6.9179(4), c = 13.0938(8) Å, β = 105.102(6)°, V = 1324.16(16)Å3, Z = 4, and R = 0.0337. Also compound 6-bromo-3-(pyridine-4-yl)-[1,2,4]triazolo[4,3-a]pyridine was crystallized in the monoclinic space group P 21/c with a = 14.3213(11), b = 6.9452(4) (4), c = 12.6860(8)Å, β = 100.265(6)°, V = 1241.62(14)Å3, Z = 4, and R = 0.0561

“BAM”: a collaborative R&D project for the development of a simulation based solution for the design and manufacture of 3D woven composites

Breakthrough Aerospace Materials (BAM) is a collaborative R&D project based in the UK [1]; led by industry and co-funded by the British Government via the Innovate-UK under its Aerospace Technology Institute (ATI) R&T Programme. The overall objective of BAM is to develop a complete process that will enable aerospace industry (and others) to design and manufacture complex shaped components using 3D woven composites. This material offers great advantages particularly for producing lightweight structures with high resistance to impact loading and damage - yet, there is still no evidence of it been widely adopted by industry! It is agreed that one of the major reasons behind slow adoption of the 3D woven composites by industry is the lack of industrial simulation tools that can be used effectively by design and analysis engineers. A consortium consisting of 12 partners, involving 9 from industry and 3 from academia, was set up to work towards this goal over a period of three years. As it is less than a year since the kick-off of the project, this paper will mainly introduce the general approach for now - leaving the full demonstration of applying the developed technologies on industrial cases for follow up publications. However, a few independent illustration examples are still presented - while elaborating on the current status of development at various steps in the process and its associated challenges. The paper also aims to highlight the interdependence between industrial and academic partners for their success in pushing the required technology up the TRL (Technology Readiness Level) scale. Two leading CAE software developers (ESI Group and MSC Software) are involved in BAM, and both are working on developing their own strategy to tackle the problem. The paper will elaborate on the approach adopted by ESI in particular, which is aligned with its global strategy for providing virtual end-to-end solution for composites product development

The Safety and Effectiveness of Apixaban in Patients with End-Stage Kidney Disease on Dialysis: A Retrospective Observational Study

Background: Apixaban has been increasingly utilized for various FDA-approved indications, including stroke prevention and venous thromboembolism (VTE) treatment in patients with end stage kidney disease (ESKD) on hemodialysis. However, the safety and efficacy of its use in this population is not well established. Hence, the purpose of this study is to evaluate the safety and effectiveness of apixaban by examining outcomes in this population. Methods: This was a retrospective observational study that involved adults with ESKD who were on hemodialysis and prescribed apixaban from our hospital’s outpatient pharmacy between 1 May 2015, and 31 March 2022. Demographics, apixaban indications, dose appropriateness, concomitant antiplatelet use, and comorbidities data were collected. Bleeding and thromboembolic events were also collected. Results: Sixty-six patients fulfilled the inclusion criteria, 50% of them males. Median age was 71 (63.5–82) years, and the median BMI 28.2 (59.5–86.25) kg/m2. The median follow-up time was 5 (1.9–12.3) months. Concomitant antiplatelet use (39.4%) and high medication adherence (84.8%) were observed. During follow-up, major bleeding events occurred in 15.2% of cases, with minor bleeding being more common (36.4%), and VTE and stroke events occurred in 4.5% of cases; appropriate dosing was prevalent (62.1%), and there was an overall all-cause mortality rate of 34.8%. Most patients received a 2.5 mg BID apixaban dose (56.1%), including both NVAF and VTE groups. Notably, the multivariate logistic regression analysis indicated that weight, and daily dose were insignificant predictors of bleeding events (p = 0.104, 0.591), however, the BMI was the main independent risk factor for bleeding in this population [OR = 0.9, 95% CI: 0.8–0.99; p = 0.023]. Conclusions: Our analysis of apixaban-treated ESKD patients highlights that the risk of bleeding is significant, and BMI was the main independent risk factor. A larger prospective study is needed to confirm our findings