Finite element analysis of 2-D tubular braided composite based on geometrical models to study mechanical performances

Tubular Braided Composites (TBC) have a higher strength to weight ratio than conventional materials and better mechanical properties compared to laminated composite materials. The optimization of the TBC and the introduction of new applications requires a comprehensive understanding of TBC’s behavior. One efficient way to study the behavior of TBC is using Finite Element Modeling (FEM). This paper will introduce a method for generating geometrical models with different patterns and variables. Micro Computed-Tomography (μCT) is also used for generating an actual 3-D model of a TBC. The geometrical model and the μCT models are visually compared. The geometrical model is inputted into the FEM software package and is studied in different conditions. Finally, the result of FEM is compared against experimental and analytical results.Natural Sciences and Engineering Research Council (NSERC) Canada RGPIN- 2018-05899. CMC Microsystems provided the software used in this study

Experimental evaluation of carbon fibre, fibreglass and aramid tubular braided composites under combined tension-torsion loading

Braided composites are a class of composite materials that feature an inter-woven structure that improves structural stability and damage tolerance. Presently, braided composites under tension and torsion loading have been studied individually. Mechanical behaviour of braided composites under combined tension–torsion loading is common and therefore requires investigation. In this study, mechanical properties of carbon fibre, fibreglass and aramid 2D tubular braided composites (TBCs) were assessed and compared under coupled tension–torsion loading. The plane stress theory investigated the failure mechanism of braids. A contact-free three-dimensional digital image correlation (3D DIC) technique was used to derive detailed and continuous strain maps and understand the buckling behaviour of TBCs.Natural Sciences and Engineering Research Council (NSERC) Canada RGPIN-2018-0589

Fiber identification of braided composites using micro-computed tomography

Braided composites contain interwoven fibers that are embedded in a matrix material. Advanced measurement methods are required to accurately measure and characterize braided composites due to their interwoven composition. Micro-computed tomography (μCT) is an X-ray based measurement method that allows for the internal structure of objects to be examined. High-resolution μCT of braided composites allows for their internal geometry to be accurately measured. Braid samples were measured with a voxel size of 1.0 μm3, which resulted in a field of view of 4.904 x 4.904 x 3.064 mm3. With this field of view, individual fibers within the braid yarns could be identified and measured. The scientific visualization software package Avizo and the XFiber extension was used to identify and measure braid yarn fibers from the collected μCT measurements. Fiber properties such as orientation angles (ϕ and θ), curved fiber length, tortuosity, and fiber diameter were obtained. Additionally, finite element mesh geometries of the braid yarns within a braided structure were created. The presented methodology provides a roadmap for the accurate modeling of braided composite unit cell geometries using high-resolution μCT data.Natural Sciences and Engineering Research Council (NSERC) Canada RGPIN- 2018-05899. CMC Microsystems provided the software used in this study

Flexural testing of cellulose fiber braided composites using three dimensional digital image correlation

Braided composites consist of woven fibers embedded within a matrix material. Braided structures are commonly produced using conventional materials such as carbon, glass and aramid fibers. However, natural fibers and bio-based resins may also be utilized with this manufacturing process. In this work, the flexural properties of tubular braid structures produced using bio-based materials was investigated. Braid samples were assessed using a contact free three dimensional digital image correlation (3D DIC) technique to assess the strain fields that occur in the samples due to applied flexural loads. Additionally, the bio-based structures were evaluated using micro-computed tomography (µCT) to assess the cross-sectional geometry and void content of the produced samples.Natural Science and Research Council (NSERC) Canada RGPIN-2018-0589

Braid CAM: Braided composite analytical model

Braided composites consist of yarns that are interwoven to produce a braided structure. Braided composites can be manufactured in a number of different configurations including: Diamond (1/1), Regular (2/2) and Hercules (3/3) braiding patterns. Braid patterns are classified by the number of yarns which pass over and under each other. Currently, few software tools are available for the design and manufacture of braided composites. Additionally, mathematical models that exist for braided composites require specialized knowledge. The goal of Braid CAM is to provide an easy to use tool for the design and manufacture of braided composites. Availability of programs like Braid CAM will help to increase the implementation of braided composites for engineering design applications. Keywords: Braided composites, Analytical model, Elastic properties, Composite material

Evaluation of fiber reinforced cement using digital image correlation.

The effect of short fiber reinforcements on the mechanical properties of cement has been examined using a splitting tensile - digital image correlation (DIC) measurement method. Three short fiber reinforcement materials have been used in this study: fiberglass, nylon, and polypropylene. The method outlined provides a simple experimental setup that can be used to evaluate the ultimate tensile strength of brittle materials as well as measure the full field strain across the surface of the splitting tensile test cylindrical specimen. Since the DIC measurement technique is a contact free measurement this method can be used to assess sample failure

Cement test sample with speckle pattern applied to surface.

<p>Cement test sample with speckle pattern applied to surface.</p

Short fiber additives dimensions and mechanical properties.

<p>Short fiber additives dimensions and mechanical properties.</p

Example strain field of cement samples of Procon M Fibers.

<p>Left images strain prior to sample failure; right images maximum sample strain).</p