Search

Fused filament fabrication (FFF) has rapidly begun to see implementation in industrial fields as a method of rapid manufacturing. Traditional FFF parts are made from a single thermoplastic polymer. The polymer is heated to its melting point and deposited on a work bed where a model is gradually built from the base up. While traditional FFF parts have low mechanical properties, a reinforcing phase allows for improved mechanical properties. The addition of a reinforcing material to the base polymer and complex internal microstructure of the 3 D printed party leads to anisotropic mechanical properties. Thus, these materials’ mechanical properties become challenging to characterize using traditional measurement techniques due to the previously mentioned factors. Therefore, it is essential to develop a method in which mechanical properties can be measured and analyzed. This study aims to characterize the mechanical behaviour under a uniaxial tensile load of an FFF produced polylactic acid (PLA)-copper particulate composite. The internal response of the FFF sample was imaged using micro-computed tomography at predetermined loads. The μ-CT images were input into an open-source digital volume correlation (DVC) software to measure the internal displacements and strain tensor fields. The study results show the development of different strain fields and interior features of the FFF parts.

Braiding is an advanced textile manufacturing method that is used to produce two-dimensional and three-dimensional components. Unlike laminated structures, braids have interlaced yarns that form a continuity between layers. This structure allows for improved impact resistance, damage tolerance, and improved through-thickness reinforcement. Despite the numerous advantages of braided composites, braids also have shortcomings. Their highly complex fiber architecture presents challenges in the availability and choice of the strain measuring and characterization techniques. Advanced measurement methods such as optical strain measurement, micro-computed tomography, and in situ strain measurement are required. Optical strain measurement methods such as digital image correlation and high-speed imaging are necessary to accurately measure the complex deformation and failure that braided composites exhibit. X-ray-based micro-computed tomography measurements can provide detailed geometric and morphologic information for braided structures, which is necessary for accurately predicting the mechanical properties of braided structures. Finally, in situ strain measurement methods will provide detailed information on the internal deformation and strain that exists within braided structures. In situ sensors will also allow for in-service health monitoring of braided structures. This paper provides a detailed review of the aforementioned sensing technologies and their relation to the measurement of braided composite structures.

Conventional damage inspection methods and characterization of carbon fiber (CF) composites are typically destructive, expensive, and do not provide spatial resolution. Non-destructive monitoring of carbon fiber composites is presented with an electroluminescent (EL) thin-film dielectric phosphor sandwiched between compacted and semi-transparent dispersed CF composite lamina. Different fractural states in the CF composite cause EL luminance changes which allows for damage detection and localization in the CF through visual inspection. The proposed methodology offers simple and effective structural health monitoring to any product manufactured from CF ranging from aerospace to high-performance sporting goods.

The fatigue behaviour of continuous wire polymer composite (CWPC) fabricated by fused filament fabrication was investigated. Four compositions were examined: polylactic acid (PLA), PLA with copper wire (Cu), thermoplastic polyurethane (TPU), and TPU with Cu wire. Residual properties were measured after different sets of number of cycles (10 , 10 , 10 ). Residual strengths were 89.736% and 70.464% of the ultimate tensile strength of the original material after 10 cycles for PLA CWPC and TPU CWPC, respectively. A one-way analysis of variance (ANOVA) statistical tests showed insignificant changes in the residual strengths of PLA-based materials after an increasing number of cycles and significant changes for the TPU-based materials. CWPC electromechanical properties under fatigue test demonstrated reverse piezoresistivity behavior. A strain-controlled fatigue life analytical model was compared to the experimental results showing good agreement. This study demonstrates the applicability of FFF technique to print sensors with continuous integrated wire with tunable properties.

With the advancement in Fused Filament Fabrication (FFF), its application is increasing widely across different industries such as aeronautical, biomedical, robotics, etc. The internal structure is becoming more complex and intricate with varying materials of reinforcement which are used to improve mechanical properties. Current measurement techniques like Digital Image Correlation (DIC) are non-destructive testing methods that do not provide enough information on the behaviour of internal microstructure for anisotropic FFF materials. Digital Volume Correlation (DVC) is non-destructive testing technique which provides full field internal 3D deformation and strain fields. Copper particle filled PLA samples manufactured using FFF method with 20, 40, 60 and 80 infill percentages were loaded in tension inside Micro-CT. X-rays were passed through the sample to get a volumetric dataset for different loadings. Using DVC method on the dataset, internal displacement and strain fields were generated for 20, 40, 60 and 80 infill percentage FFF sample.

Recently, continuous fibre reinforcement has been combined with three-dimensional (3D) printing to create stiffer printed components. This study investigates the effect of wire volume fraction, typ...

There is an increasing demand for the use of “green”-based materials as reinforcement and matrix materials in composites. However, the ability of these natural-based materials to perform as consistently and reliably as conventional materials is still relatively unknown. A key importance in the viability of these materials is the evaluation of the content of voids and imperfections, which may affect the properties of the entire composite. In this study, the microstructure of tubular-braided composites manufactured from cellulose fibers and a partially bio-derived resin was studied with the use of micro-computed tomography. These methods were used to determine the effect of modifying braid angle, resin type, and curing method on fiber volume fraction, void volume, and void distribution. It was determined that the void content increased with the increase in braid angle, and vacuum-bagging reduced the total void content. The sample with the smallest braid angle produced with vacuum-bagged curing contained a void fraction of 1.5%. The results of this study proved that the materials used could be viable for further testing and development and that micro-computed tomography imaging is valuable for identifying how to improve consistency and minimize imperfections to create more accurate and reliable natural fiber-braided composites.

Purpose This paper aims to evaluate and predict the tensile properties of additively manufactured continuous wire polymer composites (CWPCs). Design/methodology/approach An open-source 3D printer was modified to print CWPCs where metal wires act as a reinforcement within a polymer matrix. The influence of different wire materials and diameters on the tensile modulus and ultimate tensile strength was studied. Different polymer matrixes were used to investigate the effect of the matrix on CWPCs’ tensile properties. The behaviour of samples was predicted analytically using the rule of mixture micromechanical approach and investigated experimentally using an American society for testing and materials standard tensile test. Findings Experimental results showed improvement in the elastic modulus and ultimate strength of CWPCs compared with non-reinforced specimens. Deviation between the experimental data and the analytical prediction was found to be dependent on the matrix type, wire volume fraction and wire material. Originality/value This paper introduces novel continuous metal wire-reinforced 3D printed composites. The continuous wire inside the print can be used as a strain gauge which can give an early alert for material failure. Applications for CWPCs include 3D-printed pressure and temperature sensors which measure the change in the wire’s electrical resistance and 3D-printed heaters which would work by supplying current through continuous wires.

Rapidly determining root growth patterns is biologically important and technically challenging. Current methods focus on direct observation of roots and require destructive excavations or time-consuming root tracing. We developed a novel methodology based on analyzing soil particle displacement, rather than direct observation of roots. This inferred root growth method uses digital image correlation (DIC) analysis, an established and high-throughput method used in many engineering and science disciplines. By applying DIC analyses to repeated images of plants grown in clear window boxes, we produced visually intuitive and quantifiable strain maps, indicating the magnitude and direction of soil movement. From this, we could infer root growth and rapidly quantify root system metrics. Strain measures were closely associated with the spatial distribution of roots and correlated with root length measured using conventional approaches. The method also allowed for the detection of root proliferation in nutrient-enriched soil patches, indicating its suitability for quantifying biological patterns. This novel application of DIC in root biology is effective, scalable, low cost, flexible and complementary to existing technologies. This method offers a new tool for answering questions in plant biology and will be particularly useful in studies involving temporal dynamics of root processes.

Structural Health Monitoring (SHM) uses sensors in advanced engineering structures to evaluate integrity and detect damage or deformation affecting structural performance, e.g. cracks, holes, or corrosion. Carbon fiber (CF) textile composites are commonly used to reinforce structures such as aircraft, vehicles, or bridges due to their high tensile strength to weight ratio, chemical resistance, and thermal and electrical conductivity. Printing electronics on textiles is a scalable manufacturing technology combining the physical properties of textile materials with the added functionality of electronic elements making them self-sensing. Extrusion printing is a contactless digital printing method to print electrical conductors and passive circuit elements. This paper proposes to combine conventional CF composite manufacturing processes with printed conductors to create self-sensing CF textile composites. Damage is sensed by measuring resistance changes in a CF sheet. Contacts are extrusion printed directly on woven CF sheets using silver flake ink. A multiplexed Kelvin Double Bridge circuit is the read-out interface. This allows small resistance changes due to damage to be measured in a four-point configuration. The circuit is connected to the printed contacts on the CF sheet through multiplexers to detect damage in different locations. This 2D digital sensor can detect the location and size of damage holes for SHM. The resolution of the sensor is controlled by the location and spacing of the silver electrodes, which were studied experimentally and by simulation. The resolution is 26 mm in the current direction and 16 mm in the orthogonal direction. The threshold of detectable damage is 4 mm2. Simulation of the sensor as an isotropic 2D conductor shows good agreement with experimental results for the orthotropic fabric. The resultant sensing device could be integrated into many composite structures as one of its layers or simply printed on the surface to create smart structures.

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 μm 3, 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.

In this study, the electromechanical properties of two different three-dimensional (3D) printed continuous wire polymer composites (CWPC) were characterized and compared. The two composite materials were copper wire polylactic acid (PLA) composite (rigid material) and copper wire polyurethane (PU) composite (flexible material). The electromechanical measurements were based on piezoresistive properties of the sensor at which the mechanical strain and the electrical resistance were correlated under a uniaxial loading condition. Both types of materials exhibited a direct linear relationship between the two quantities, indicating the ability of CWPC to be used for strain sensing applications. The gauge factor (GF) sensitivity was compared for the two types of materials. It was found that there is no statistical significance difference between the GF of PLA CWPC (1.36 ± 0.14) and PU CWPC (1.29 ± 0.07)); therefore, the sensing property depends mainly on the wire integrated into the 3D-printed structure rather than the matrix. Thus, different matrices can be used to fit different applications. An analytical model for GF showed agreement with the experimental results for both materials. PU CWPC showed significant improvement in both Young’s modulus (E) and ultimate tensile strength (UTS) (210.5 % and 31.86 %, respectively), compared with pure PU, while the change in Poisson’s ratio (ν) was insignificant. Young’s modulus of PLA CWPC was significantly increased by 80.3 % compared with PLA, while UTS and ν did not significantly change. The experimental mechanical properties showed good agreement with data from the analytical models. The outcome of this study focused on the manufacturing of 3D-printed functionalized structure for strain sensing applications with improved mechanical properties. The wide range of attained strain allowed their use in different applications based on the range of strain needed, such as rigid sports equipment and flexible wearable sensors.

There has been a growing trend towards producing functional components using additive manufacturing (AM). A Continuous Wire Polymer Composite (CWPC) manufacturing method using an open-source desktop 3D printer is presented. The incorporation of continuous wires within AM structures results in a composite structure. The reinforcement of AM components with continuous wires results in improved mechanical properties and wire reinforcement can be oriented in critical locations of AM components. The CWPC manufacturing method will allow for fabrication of thermal and mechanical sensors for temperature and strain, 3D printed heating elements and for high strength components.

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.

Digital volume correlation (DVC) can be implemented via micro-computed tomography (μ-CT) to resolve 3D strains. For proper correlation, microstructure detail is required. This study aims to provide a methodology for obtaining optimal DVC image datasets for composite materials by adding contrast particles to an epoxy resin. Image segmentation was utilized to ensure each particle met analysis DVC baselines. Particles with sizes of 10, 25, 50 and 200 μm were investigated. The 25 μm copper particles provided the greatest accuracy. These particles were embedded into an epoxy sample with a hole and subjected to uniaxial compression. Downsampled μ-CT and full-resolution datasets were compared to demonstrate processing strategies for DVC analysis.

Braided composites can be manufactured in a variety of braid patterns: Diamond (1/1), Regular (2/2), and Hercules (3/3) and with longitudinal reinforcement (Triaxial). The complex strain fields, which could help reveal phenomenological behavior of braids, have not been experimentally assessed. As such, the objectives of this article were to investigate the effect of braid pattern (Diamond, Regular), braid angle (35°, 45°, 55°), and load (tensile, torsion) on the strain field and elastic properties (longitudinal and shear moduli) using a three-dimensional digital image correlation method. The methodology presented in this manuscript will be used to validate a new analytical model, which predicts the elastic properties of tubular braided of both varying braid type and braid angle.

Tubular braided composites are manufactured using a Maypole braiding machine which interlaces yarns in order to manufacture a braided structure. Braids can be produced in Diamond (1/1), Regular (2/2) and Hercules (3/3) patterns. In addition, axial yarns can be included in order to produce triaxial braid structures. Several analytical and finite element analysis models have been developed in order to predict the elastic properties of braided composites. Despite the fact that many models exist for braided composites, a comprehensive model has not been presented that can capture the variety of braiding patterns which can be manufactured using the braiding process. In this study, a new analytical model has been developed that can describe the elastic properties of Diamond, Regular and Hercules braids. The proposed analytical model uses a volume averaging stiffness method in order to account for yarn undulations and the orientation of braid yarns within the braid structure. The model presented here has been compared with the existing FEA and analytical models and has also been validated experimentally. Experimental validation comprised tensile and torsional tests in order to predict the longitudinal and shear moduli for both Diamond and Regular braid geometries. The experimental and proposed model results highlight the effect of braiding pattern and braiding angle on the mechanical properties.

Three dimensional (3D) printing is a technique conventionally used to manufacture prototypes. Commercial desktop 3D printers have become available which produce functional 3D printed parts. The MarkOne by Mark Forged manufactures printed structures reinforced with continuous Carbon, Fiberglass or Kevlar fibers. The aim of this study is to evaluate the elastic properties of the fiber reinforced 3D printed structures and predict elastic properties using an Average Stiffness (VAS) method. Samples evaluated in this study were produced by varying the volume fraction of fibers within the 3D printed structures (4.04, 8.08 and 10.1% respectively). The experimentally determined elastic modulus was found to be 1767.2, 6920.0 and 9001.2 MPa for fiber volume fractions of 4.04, 8.08 and 10.1% respectively. The predicted elastic moduli were found to be 4155.7, 7380.0 and 8992.1 MPa. The model results differed from experiments by 57.5, 6.2 and 0.1% for the 4.04, 8.08 and 10.1% fiber volume fractions. The predictive model allows for the elastic properties of fiber reinforced 3D printed parts. The model presented will allow for designers to predict the elastic properties of fiber reinforced 3D printed parts to be used for functional components which require specific mechanical properties.

Utilization of Polyvinylidene fluoride (PVDF) open-cellular foam allows for the creation of high-efficiency Triboelectric nanogenerators (TENG). The micro-structure of TENG devices can be problematic to characterize accurately using conventional methods like scanning electron microscope (SEM). This work aims to provide a methodology in which representative 3D measurements can be made on open-cellular PVDF foams. Open-cell PVDF foams were produced through a salt-leeching procedure. Analysis of the PVDF foams was done by imaging the sample through a desktop micro-computed tomography (μ-CT) machine to allow for a full 3D dataset to be obtained. Foams were produced with salt sizes of 250–500 μm, 106–250 μm, 53–106 μm, and

Unmanned Aerial Vehicles (UAVs) are increasingly used to deliver items and gather information in remote areas. As a result, UAVs suffer from ice accumulation on their wings, which drastically affects their flight. However, the UAV industry is still relatively young and, thus, commercial solutions for de-icing on UAVs are limited. The use of carbon fiber composites is becoming increasingly ubiquitous for UAVs as well as many other industries such as military, construction, medical, automobile, sporting goods and aircraft systems. Carbon fiber is commercially available in various forms, including single yarns, braids and weaves, which are similar to traditional textiles. This paper presents a method to create a self-heating composite structure that can be integrated into UAV wings for de-icing by exploiting the thermal and electrical conductivity of carbon fiber. Extrusion printing is used to fabricate electrical contacts directly on the carbon fiber weave. Extrusion printing on textiles faces multiple challenges that are overcome in this paper. A method is presented to extrusion print conductive paste on textiles. Specifically, carbon fiber weaves. This manufacturing method is employed to fabricate carbon fiber-based heating devices, and they are characterized electrically and thermally.

Two dimensional (2D) tubular braided composites consist of textile fibers imbedded in a resin matrix. Braid geometry and void content will affect the mechanical behavior of the tubular braided composite samples. In this study, tubular braid samples were assessed using micro X-ray computed tomography (μCT) to evaluate sample porosity/void content and to identify the strand geometry of the reinforcing fibers. The process described in this manuscript can be used to assess the quality and consistency of the tubular braided composite manufacturing process.

Torque is applied to orthodontic brackets in order to alter the buccal-lingual angulation of a tooth. One factor that can affect torque is the ligation mode used to retain the archwire in the bracket slot. The objective of this study was to investigate the effects of stainless steel ligation on torque expression and bracket deformation.This study utilized 60 upper right central incisor Damon Q brackets and 60 Ormco Orthos Twin brackets. The brackets used in this study were subdivided into four groups: (1) Damon Q ligated with SS ligature; (2) Damon Q with the sliding bracket door; (3) Orthos Twin bracket ligated with SS wire; and (4) Orthos Twin ligated with elastic ties. All brackets were tested using an orthodontic torque simulating device that applied archwire rotation from 0° to 45°.All brackets ligated with stainless steel ties exhibited greater torque expression and less deformation than brackets without stainless steel ties. As well, Damon Q brackets exhibit less bracket deformation than Orthos Twin brackets.Stainless steel ties can reduce the amount of plastic deformation for both types of brackets used in this study.

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.

The design and testing of an orthodontic torque simulator that reproduces the effect of archwire rotation on orthodontic brackets is described. This unique device is capable of simultaneously measuring the deformation and loads applied to an orthodontic bracket due to archwire rotation. Archwire rotation is used by orthodontists to correct the inclination of teeth within the mouth. This orthodontic torque simulator will provide knowledge of the deformation and loads applied to orthodontic bracket that will aide clinicians by describing the effect of archwire rotation on brackets. This will also impact that design on new archwire\bracket systems by providing an assessment of performance. Deformation of the orthodontic bracket tie wings is measured using a digital image correlation process to measure elastic and plastic deformation. The magnitude of force and moments applied to the bracket though the archwire is also measured using a six-axis load cell. Initial tests have been performed on two orthodontic brackets of varying geometry to demonstrate the measurement capability of the orthodontic torque simulator. The demonstration experiment shows that a Damon Q bracket had a final plastic deformation after a single loading of 0.022 mm while the Speed bracket deformed 0.071 mm. This indicates that the Speed bracket plastically deforms 3.2 times more than the Damon Q bracket for similar magnitude of applied moment. The demonstration experiment demonstrates that bracket geometry affect the deformation of orthodontic brackets and this difference can be detected using the orthodontic torque simulator.

The objective of this paper is to assess changes in braid radius and braid angle of braided composite tubes under tensile loading using stereomicroscope digital image correlation (DIC) based optical measurement techniques. Using this approach, displacement fields were calculated and three dimensional surfaces were reconstructed. The radius of the tube and the braid angle were determined from the reconstructed surfaces and images. With this initial work showing the effects of tensile loading on the tube radius and braid angle also included development of approaches for deconstructing data. Results highlight that there is ∼10% difference between findings for elastic modulus between existing investigation techniques and the methods developed here for rigid-matrix composite braids.

Introduction Archwire rotation is used in orthodontic treatment to alter the labiolingual orientation of a tooth. Measurement of the 3-dimensional (3D) motion of the orthodontic brackets requires a new configuration of the orthodontic torque simulator. Methods The orthodontic torque simulator was coupled with a stereo microscope and 2 cameras to allow for the 3D bracket motion to be determined during wire twisting. The stereo camera images were processed with a 3D digital image correlation technique to determine the 3D deformation of the orthodontic brackets. Three self-ligating brackets (Damon Q, Ormco, Orange, Calif; In-Ovation R, GAC, Bohemia, NY; and Speed, Strite Industries, Cambridge, Ontario, Canada) were compared by using the 3D digital image correlation method to demonstrate the difference in 3D motion of self-ligating brackets components. Results Contour plots of the 3 brackets demonstrate the 3D motion of the bracket tie-wings and the archwire retentive component. The 3D motion of the bracket tie-wings and archwire retentive component were quantified. The displacement values of the archwire retentive component measured with the 3D orthodontic torque simulator were found to be 2.0 and 3.5 times less for the In-Ovation and Damon Q brackets than the values in previous studies that examined the compliance of the archwire retentive component. Conclusions The 3D digital image correlation method used to quantify bracket deformation showed the 3D motion of the bracket tie-wings and the motion of the archwire retentive component. The use of a 3D optical measurement system is useful to understand the motion of the archwire retentive component but is not necessary to quantify bracket tie-wing motion. This measurement technique can be used to evaluate brackets of varying designs.

Completing composite calculations can be very tedious and impractical in the field. Herein, we provide some background on, and instructions for, using the braided composite app developed by our group. This tool is meant to be very useful to the professional in the field, exploring structures and reinforcement, or to the student and designer, who wishes to verify calculations or get a better appreciation of the impact of certain variables on the mechanical properties of composites and, more specifically, braided composites. The app follows much of the work done in the chapters of the book: Handbook of Advances in Braided Composite Materials: Theory, Production, Testing, and Applications , J. P. Carey, Ed. Woodhead Publishing, 2016.

Braided composites have been modeled with varying degrees of success for a number of years. Many different models, starting from simple geometric representations with simplistic assumptions to complex numerical models, have been developed. In this work, models are presented from historical and practical perspectives and provide insight in the value of each approach. Some of the most used methods include the Classical Laminate Plate Theory-based models (CLPT), Fabric Geometry Models (FGM), volume averaging methods, and Finite Element Analysis (FEA) models. Each approach has advantages and disadvantages; modeling the behavior of braided composites and understanding their capability is critical to predicting the behavior of braided composites. From the information provided here, researchers and engineers can reproduce or build upon these to meet their fundamental or applied needs for the panoply of different two-dimensional or three-dimensional architectures.

In an industrial world aiming to improve processes and end-products, the use of braided composites has been minimal compared to other composite materials. Considering the well-known advantages of braided composites, this is surprising. However, the complex nature of braiding production, modeling, and design processes have been contributing factors. In this work, we present a discussion of the fundamental steps and considerations for designing braided composites and successful examples where they have been used. This work is intended to guide junior designers through a thorough design process and lay out a road map for experienced designers.

Braided composites can fulfill the needs of a great number of applications. Yet their use is sparse at best in industrial applications compared to other composite material production methods. Herein we assess the state of braided composites, provide general insight in their history, geometry, behavior, and provide a road map to predicting their behavior.

Braided composite materials are one of the oldest textiles, but their adoption in industry, for mass-market or high-end products, is limited. The braiding process allows for versatility in the production of end products; such an advantage in the production process requires stringent assessment and quality control of the end product, or accurate modeling and design of components. However, the development of fully validated models to predict the large range of required material properties that would be highly beneficial for a priori design of braided component is hampered by the lack of consistent use of accurate testing methodology. Testing protocols specific to braided composites in terms of sample geometry, material quality, and mechanical properties do exist, but are often combined with those for other textile composites. This lack of concise information and list of key testing protocols for two- or three-dimensional braided composites, of flat or of complex shape, are hindering potential material engineers or researchers from assessing their properties. Herein, the most applicable standard and nonstandard testing procedures for braided composite materials and structures are concisely assembled.

Braiding is not being used as a manufacturing process as much as would be expected based on its well-known advantages. Fabricating consistent, high-quality braided composite materials has been challenging. The range of available processes and selecting the right one for the right component has perplexed researchers and engineers. Herein, production processes and methods, as well as alternatives, for the production of two-dimensional and three-dimensional braided composites are discussed.

Orthodontic torque expression is the result of axial rotation of rectangular archwires within a rectangular bracket slot. This study investigates the effect of bracket material on torque expression. Torque exerted by a rotating archwire on each bracket will be measured as well as the relative deformation of each bracket slot. A total of 60 tests were performed where archwires were rotated within a bracket slot to produce torque within a bracket. Thirty Ormco Orthos Ti and 30 Orthos SS were compared to investigate the effect of torque on bracket material. Each bracket was mounted on a six-axis load cell that measured forces and moments in all directions. The archwire was rotated from an initial angle of 0 degree in 3 degrees increments to maximum angle of 51 degrees and then returned to the initial position. An overhead camera took images at each 3 degrees increment. The bracket images were post-processed using a digital image correlation technique to measure the relative deformation of each bracket slot. The maximum torque expressed at 51 degrees was 99.8 Nmm and 93.0 Nmm for Orthos Ti and Orthos SS, respectively. Total plastic deformation measured at 0 degrees post-torquing of the Orthos SS was 0.038 mm compared to 0.013 mm for Orthos Ti. The Orthos Ti brackets plastically deformed less than the Orthos SS brackets after torquing. The Orthos SS bracket plastic deformation was 2.8 times greater than that of Orthos Ti brackets. The Orthos Ti brackets expressed more torque than the stainless steel brackets but exhibited substantial variation.

Braided composites are formed by interlacing continuous fibers into a textile pre-form and then impregnating the pre-form within a matrix material. Braid mechanical properties are manipulated through the selection of matrix, fiber and braid geometry. Braided composites are produced with conventional materials like carbon, aramid and glass fibers; however, they can also be produced using natural fibers such as jute, hemp, flax or regenerated cellulose. The mechanical properties of conventional and natural braided composites are highly affected by voids within the braided structure. The effect of voids on braided structures must be investigated to improve braided composite performance. A high-resolution micro-computed tomography (μCT) measurement method was utilized to quantify the size and distribution of voids within natural fiber-bio resin braided composite structures. Image processing techniques were employed to quantify void, matrix and fiber content within 35° and 45° braid samples. Accurate quantification of fiber, matrix and void volumes are crucial for evaluating the quality and repeatability of the braided composite manufacturing process. Reduction of voids and pores will improve braided composite mechanical properties and performance. Measurement of the constituents within braided composites is also necessary for the development of accurate models for predicting braid mechanical properties. Measurement of the internal microstructure of braided composites will allow for the development of improved analytical and numerical braided composite models.

Braided composites are highly valuable engineering structures. However, they have not had a significant impact on the civilian aerospace industry until recently. The Airbus A350-1000, which is currently under development, marked one of the first large-scale aerospace applications of braided composites in its early planned developments. Herein, some of the fundamental concepts of braids and braided composites are reviewed. Types of braided structures and materials best suited for aerospace applications are explored, as well as their advantages and disadvantages. The mechanical behaviour of braided composites' structures and methods used to model their properties are introduced. Finally, current aerospace applications of braided composites in the aerospace industry are examined.

Background The primary objective of this study was to develop a computer-controlled three-dimensional friction measuring system, the orthodontic friction simulator (OFS). A clinically-based in vitro experiment considering wet and dry friction for conventionally and self-ligated brackets is presented to elucidate debate surrounding sliding mechanics and illustrate capabilities of the OFS. Methods The OFS was designed and manufactured using sound engineering principles and with the primary concern of being able to measure all forces and moments generated during sliding mechanics. This required the implementation of a six-axis load cell. A variety of translation and rotation stages were also incorporated to allow for precise positioning of the bracket relative to the archwire. Once designed and built, the OFS was then used to compare conventional and self-ligation methods in both the wet and dry state. Damon Q brackets and 0.018″ × 0.025″ stainless steel wires were used for all tests with a sample size of n = 65 for each ligation method. Archwires were pulled at a speed of 0.1 mm/s in 11 increments of 0.1 mm. At each increment, the bracket would be rotated 0.5° resulting in a total archwire travel of 1.1 mm and a second-order bracket angle range of 0°–5°. A repeated measures ANOVA was conducted to determine if ligation method and/or addition of moisture effected resulting orthodontic loads. Results The developed equipment for studying orthodontic sliding mechanics was able to measure forces and moments in all three directions; a capability not previously realized in the literature. Additionally, it was found that passive ligation significantly reduced resistance to sliding, P ≤ 0.05, while the dry/wet state did not. Conclusions The OFS certainly proved to be an adequate instrument for the scientific evaluation of orthodontic sliding mechanics. It is capable of measuring loads generated in all directions and is a fully automated apparatus allowing for simple and repeatable friction tests to be conducted. Furthermore, the addition of saliva was not found to significantly influence the loads generated during sliding mechanics regardless of ligation method.