Buckling and strength analysis of panels with discrete stiffness tailoring

Continuous variation of stiffness across flat plates has been shown, theoretically, to improve buckling performance by up to 60%. However, steered fibre manufacturing methods cannot achieve the minimum radius of curvature required for improvement whilst maintaining a high deposition rate. An alternative concept, Discrete Stiffness Tailoring (DST), which varies stiffness within a ply through discrete changes of angle, is compatible with high rate deposition methods such as Advanced Tape Laying. Through the simple example of redistribution of the material in a quasi-isotropic [±45/90/0]2S laminate whilst maintaining ply percentages, DST is shown both experimentally and theoretically to improve buckling stress by at least 15% with no indication of failure in regions of discrete angle change (seams). However, the reduced tensile strength of seams obtained by virtual and experimental testing means that increased buckling performance in the principle load direction needs to be balanced against loss of transverse strengthThis work was supported by the UK EPSRC ADAPT research project (grant number EP/N024508/1) which is gratefully acknowledged. Richard Butler is supported by a Royal Academy of Engineering and GKN Aerospace Research Chair. Lucie Culliford’s PhD studentship is 50% funded by GKN Aerospace

Effects of Bovine Colostrum with or without Egg on In Vitro Bacterial-Induced Intestinal Damage with Relevance for SIBO and Infectious Diarrhea.

Small intestinal bacterial overgrowth (SIBO) occurs commonly, is difficult to treat, and frequently recurs. Bovine colostrum (BC) and chicken eggs contain immunoglobulins and other components that possess antimicrobial, immunoregulatory, and growth factor activities; however, it is not known if they have the ability to reduce injury caused by the presence of bacteria associated with SIBO (Streptococcus, Escherichia coli, Staphylococcus, Bacteroides, Klebsiella, Enterococcus, and Proteus) and infectious diarrhea (enteropathogenic Escherichia coli, Salmonella). We examined the effects of BC, egg, or the combination, on bacterial growth and bacteria-induced changes in transepithelial electrical resistance (TEER) and bacterial translocation across confluent Caco-2 monolayers. BC, egg, or the combination did not affect bacterial growth. Adding bacteria to monolayers reduced TEER and (with minor variations among species) increased bacterial translocation, increased monolayer apoptosis (increased caspase-3 and Baxα, reduced Bcl2), increased intercellular adhesion molecule 1 (ICAM-1), and reduced cell adhesion molecules zonulin1 (ZO1) and claudin-1. BC, egg, or the combination reduced these effects (all p < 0.01) and caused additional increases in vascular endothelial growth factor (VEGF) and Heat Shock Protein 70 (Hsp70) expression. We conclude that BC ± egg strengthens mucosal integrity against a battery of bacteria relevant for SIBO and for infectious diarrhea. Oral BC ± egg may have clinical value for these conditions, especially SIBO where eradication of precipitating organisms may be difficult to achieve

A review of advancements in synthesis, manufacturing and properties of environment friendly biobased Polyfurfuryl Alcohol Resin and its Composites

The quest for environmentally friendly and sustainable materials in the production of fibre reinforced composite materials has led to the use of biobased materials, which are easily accessible and renewable. Biomass-derived chemicals, their derivatives, and their applications have become increasingly prevalent in various industries and processes, greatly contributing to the goal of ecological sustainability. The biobased Polyfurfuryl Alcohol (PFA) resin is one of such polymeric materials that is gaining attention for composite applications due to its endearing Fire Smoke and Toxicity properties. Derived from agricultural by products such as sugar cane bagasse, it has been known for applications within the foundry, coating, and wood industries. However, there has been a growing interest in its use for fibre reinforced composite applications. For this reason, this work intends to provide a comprehensive review of the PFA resin in relationship to fibre reinforced composites applications. The work provides an in-depth discussion on the synthesis, curing process, manufacturing, and properties of the PFA resin as well as its composites

Off-axis tensile performance of notched resin-infused thermoplastic 3D fibre-reinforced composites

This study presents a comparison of off-axis tensile performance for notched (open-hole) and unnotched (no-hole) 3D fibre reinforced composites (FRC) specimens having two different types of matrices. The two matrix systems compared are, a novel infusible thermoplastic (Elium) resin and conventional thermoset (epoxy). Three different configurations, (one unnotched and two notched) were tested for each 3D-FRC. The resulting notched net strength, gross strength, failure strains, notch sensitivity and energy absorbed by each configuration were evaluated and compared. Additionally, 2D digital image correlation (DIC) was used to evaluate full-field strain distribution in each case. The results elucidate that thermoplastic 3D-FRCs are notch insensitive irrespective of the notch size and possess higher failure strains (around 30 percent in the cases investigated) and energy absorption (around 33 percent in the cases investigated). In contrast, thermoset 3D-FRC appeared to be notch sensitive, as the notched size increased, and they failed at lower axial strains (up to 60 percent reduction compared to unnotched specimens for the size investigated). Thus, resin-infused thermoplastic off-axis configurations are effective for composite joint applications, particularly in notch-insensitive designs, requiring higher energy absorption and failure strains

Regional Integration of Equity Markets in Sub-Saharan Africa

Equity markets in developing and emerging economies have grown in number and importance as a result of financial market globalisation. However, their role in economic growth and development is enhanced if nascent markets are integrated with well-established ones. Market integration, measured by the transmission of returns volatility, is identified across a sample of SSA countries, using a unique dataset. Evidence for potential integration between financial markets in Sub-Saharan Africa (SSA) is found. Spillovers are found across markets, some unidirectional and others bi-directional. However, continued illiquidity and incomplete institutions indicate that an integrated financial community remains premature, and considerable regulatory reform and harmonisation will be necessary for this to succeed

Multiscale Damage Modelling of Notched and Un-Notched 3D Woven Composites With Randomly Distributed Manufacturing Defects

This work proposes a stochastic multiscale computational framework for damage modelling in 3D woven composite laminates, by considering the random distribution of manufacturing-induced imperfections. The proposed method is demonstrated to be accurate, while being simple to implement and requiring modest computational resources. In this approach, a limited number of cross-sectional views obtained from micro-computed tomography (µCT) are used to obtain the stochastic distribution of two key manufacturing-induced defects, namely waviness and voids. This distribution is fed into a multiscale progressive damage model to predict the damage response of three-dimensional (3D) orthogonal woven composites. The accuracy of the proposed model was demonstrated by performing a series of finite element simulations of the un-notched and notched tensile tests (having two different hole sizes) for resin-infused thermoplastic (Elium®) 3D woven composites. Excellent correlation was achieved between experiments and the stochastic finite element simulations. This demonstrates the effectiveness of the proposed stochastic multiscale model. The model successfully captured the stochastic nature of tensile responses (ultimate tensile strength and stiffness), damage modes (matrix damage and fibre failure), and initiation and propagation of transverse cracks in thermoplastic 3D woven composites, consistent with experimental observation. The stochastic computational framework presented in this paper can be used to guide the design and optimization of 3D textile composite structures

Forming low-cost, high quality carbon tows for automotive application.

Carbon fiber reinforced composites are widely used in many industries due to their high performance. Its application in the aerospace industry has increased significantly, however, in mass produced automobile sector it is still limited. The current production of carbon fiber tow is slow and capital intensive. Thus, carbon manufactures produce higher tow counts to increase production rate to reduce its cost. In order to offset the higher cost of carbon fiber composite, an innovative and unique approach has been developed. The higher tow count carbon spools are split into smaller tow counts. Due to the delicate nature of carbon fiber, it is important to control the filamentation during that process. Different splitting process line strategies have been developed in this research work for understanding the process limitations and challenges involved. The process was made feasible for production by developing a fully automated process line with a laser feedback system. The system splits a 12K spool into two 6K tows. The quality of the 6K split tows has been determined statistically by recording real time data from the laser during the splitting process. It was demonstrated that the proposed process effectively controls filamentation and produces consistent tow quality.Company research funding by Bentley Motors Limite

Bearing performance and damage characteristics of rein-infused thermoplastic 3D woven composites bolted joints

This paper presents a comprehensive study on the single-bolt single-shear (SBSS) and double-bolt single shear (DBSS) lap joint performance of resin-infused thermoplastic 3D fibre-reinforced composite (FRC) in on-axis (0°and 90°) and off-axis (45°) configurations. The bearing performance and failure mechanisms are compared with thermoset 3D-FRC. The resin-infused thermoplastic 3D-FRC bolted joint shows improved bearing performance in terms of higher ultimate bearing strength, stiffness loss strength, and reduced damage severity than its thermoset counterpart. Additionally, this paper presents a detailed study on the intermediate and final failure mechanisms, obtained from scanning electron microscopy of the interrupted and ultimate bearing tests, to understand damage progression in SBSS and BDSS lap joints at the submicron level. The major damage characteristics of a thermoplastic 3D-FRC bolted joint include plastic deformation and plastic kinking at the hole front tip, which improve the bearing capacity and reduce stress concentration, damage severity, and its deleterious effects

Association of serum asymmetric dimethyl-arginine and troponin I levels as a risk of myocardial infarction in thalassemia

Background: The current study evaluated level of serum asymmetric dimethylarginine (ADMA) and its association to cardiac biomarkers in thalassemia patients for early diagnosis of abnormality in myocardial infarction. Subjects and methods: This study was conducted on 80 subjects divided into four groups each with 20 subjects. Group I: Control: healthy subjects. Group II: Myocardial infarction: Patients with elevated serum troponin T. Group III: thalassemia patients. Group IV: thalassemia with myocardial infarction patients: Included 20 thalassemia patients with Myocardial infarction. Serum samples were subjected for assay of creatine kinase (CK:MB), Lactate dehydrogenase, troponin I ,ADMA, Serum MDA level was determined. Results: Data obtained showed that serum CKMB, LDH1, AST, Troponin T and ADMA levels were significant elevated in MI with or without Thalassemia compared with control groups. Serum MDA was statistically significantly elevated in MI with or without Thalassemia compared with control groups. The serum level of troponin T showed an area under curve (AUC) of 0.92 ,(sensitivity 91.0 % and specificity, 88%). Also, the ADMA supported the diagnostic profile, showing an AUC of 0.85 with (sensitivity, 92.0%; specificity, 91,9%). Conclusion: Serum ADMA is sensitive marker for incidence of MI in thalassemia patients.Keywords: CKMB, LDH1, AST, Troponin T, asymmetric dimethylarginie, Thalassemia