Optimum Cord-Preg Design Using Braiding Technique.

Shen, Y., David Branscomb, David Beale, Royall Broughton, W. Foster, and S. Adanur. “Optimum Cord-preg Design using Braiding Technique.” Composites Part A. (SUBMITTED)

ABSTRACT

This paper proposes an innovative method to braid composite yarns called cord-pregs with distinctive cross-sectional shapes. The composite yarn consisting of core and jacket is characterized with tailored properties for fast manufacturing and has been demonstrated to be an ideal material to fabricate super lightweight open truss structures. The cross-sectional shape can be altered by manipulating the architecture of the braided jacket and fiber core. Composite yarns with different cross-sectional shapes but the same cross-sectional area were manufactured and compared, including triangular, square, hollowed square and circular shapes. Strength and stiffness in axial compression with buckling, and short-beam compressive failure, and three-point beam bending were studied for each cord-preg shape. The as-manufactured cord-preg with triangular cross-sectional shape has the highest bending stiffness, whereas a circular shape has the lowest. It is experimentally demonstrated that the bending stiffness with triangular cross-sectional shape can be increased by 60 percent over a circular cross-sectional shape. A computer aided design (CAD) representation based on a mathematical model is proposed to visualize the geometry of various cord-pregs.

The Design of Optimal Lattice Structures Manufactured by Maypole Braiding.

Gurley, Austin, David Beale, Royall Broughton, and David Branscomb. “The Design of Optimal Lattice Structures Manufactured by Maypole Braiding.” Journal of Mechanical Design 137, no. 10 (August, 2015): 101401.

ABSTRACT

Beginning with the maypole braiding process and its inherent constraints, we develop a design methodology for the realization of optimal braided composite lattice structures. This process requires novel geometric, mechanical, and optimization procedures for comprehensive design-ability, while taking full advantage of the capabilities of maypole braiding. The composite lattice structures are braided using yarns comprised of multiple prepreg carbon fiber (CF) tows that are themselves consolidated in a thin braided jacket to maintain round cross sections. Results show that optimal lattice-structure tubes provide significant improvement over smooth-walled CF tubes and nonoptimal lattices in torsion and bending, while maintaining comparable axial stiffness (AE).

Rapid Design of Minimal-Weight Open-Structure Composite Beams.

Austin Gurley, David Branscomb, David Beale, and Royall Broughton, “Rapid Design of Minimal-Weight Open-Structure Composite Beams” ACMA / CAMX – The Composites and Advanced Materials Expo, Orlando; 2014. Covina: Society of the Advancement of Material and Process Engineering, 2014.

SUMMARY

The newly developed concept of Open-Architecture Composite Structures (O-ACS) has proven useful in minimal weight beam applications; the method’s high specific stiffness matches expectations of composite materials, while its rapid manufacturing allows cost-effective production. To-date, prototype development has principally been based on trial-and-error and has yielded great improvements in design. However, despite the wide design range that can be achieved by the O-ACS, there has not yet been a comprehensive model for designing the structures. This work is an application of structural optimization within geometric constraints of braided truss structures, building a foundation for the scientific design of minimal-weight braided composites. An overview of modern braiding technology is given as it applies to development of lattice composite structures. Geometric modelling is shown to accurately replicate the braiding geometry. A finite-element technique is applied to this model and proven to predict the stiffness of the structures. The analysis capabilities are incorporated into an optimization method which assists the O-ACS designer by calculating ideal braiding geometries. The optimization considers both the expected design loads as well as the braiding equipment available for manufacturing, making this method an all-encompassing tool for minimal weight braided structure design.

New Directions in Braiding.

Branscomb, David, David Beale, and Royall Broughton. “New Directions in Braiding”. Journal of Engineered Fibers and Fabrics 8, no. 2 (2013): 11-24.

ABSTRACT

It is the intent of this manuscript to provide a general treatment of braiding: past, present, and future. A history and evolution of braiding, braiding machinery, and related engineering developments is provided with emphasis on the design, manufacture, and analysis of braided fabrics and composites. Some recent developments are briefly described, including: 1. a composite braider with axial yarns which interlace with the helicals, and in which the helical yarns do not interlace with each other – a machine now under commercial development, 2. a new braided structure, called the true triaxial braid, produced by the new machine or by proper carrier loading on a conventional Maypole braider; and 3. a computer controlled take-up system using image analysis to monitor and control braid formation. Original work ongoing at Auburn University is described and involves Jacquard lace braids with open structures for use in composites, computer aided design (CAD), computer aided manufacturing (CAM), and analysis of ordinary and lace braids for composite applications. This paper is an expanded version of an invited presentation under the title “New Directions in Braiding” at a Fiber Society presentation in Bursa, Turkey, in the spring of 2010.

Open-Architecture Composite Tube Design and Manufacture.

Branscomb, David. Austin Gurley, David Beale, Royall Broughton, “Open-Architecture Composite Tube Design and Manufacture” ASME Early Career Technical Journal 2012 ASME Early Career Technical Conference, ASME ECTC November 2 – 3, Atlanta, Georgia USA. In ASME Early Career Technical Journal 11, no. 7 (2012): 270-6.

ABSTRACT

An open-architecture composite tube is designed, manufactured, and tested for torsional applications. A computer aided design (CAD) based design process is presented. Topological optimizations performed in ANSYS Workbench are utilized as a design target. The resulting lattice-like pattern is realized using a conventional Maypole braiding machine to produce an open-architecture composite. A solid composite tube of similar weight and major dimensions is also manufactured and tested. The experimental results from torsion testing of the solid tube and the open architecture tube are compared and discussed. Two analytical models are derived from the kinematics of the braiding machine components to produce three dimensional CAD models facilitating visualization, design parameterization, and finite element analysis. The merits of the analytical models are discussed and compared with physical testing results.

Mathematical Analysis of Rope Braiding.

Isaac, Mitchell J., Chad L. Rodekohr, and David J. Branscomb. “Mathematical Analysis of Rope Braiding.”ASME Early Career Technical Journal 2012 ASME Early Career Technical Conference, ASME ECTC November 2 – 3, Atlanta, Georgia USA. In ASME Early Career Technical Journal 11, no. 5 (2012): 211-18.

ABSTRACT

This paper explores the physics and mathematics of the processes involved in braiding rope. When braiding rope, the braid point comes to an equilibrium point that correlates with the ratio between the take-up speed and the angular velocity of the braid machine. We examined the transitions between equilibrium points in search of an analytical equation that will describe the motion of the braid point. To validate analytical equations, a 16-yarn, diamond braided rope was braided to transition between equilibrium points, digital images were taken, and image analysis was done to collect data. The large amounts of collected data was analyzed using Mathematica®, a powerful math software package. This research resulted in two analytical equations and several empirical equations. The empirical equations found from the data were used to validate the analytical equations.

Fault Detection in Braiding Utilizing Low‐cost USB Machine Vision.

Branscomb, David, and David G. Beale. “Fault Detection in Braiding Utilizing Low‐cost USB Machine Vision.” Journal of the Textile Institute 102, no. 7 (July 2011): 568–81.

ABSTRACT

This paper investigates the effect of yarn tension on braid formation point (braid point) motion. A computer‐controlled take‐up machine is developed to facilitate braiding experiments. The results of several experiments are used to recognize tension aberrations that lead to poor quality and wasted product. Optimal braid performance is observed, which serves as the baseline for comparing the behavior of faults. By studying the effects of common faults, a diagnostic tool is developed to recognize the onset of defects and provide some insight into what might be causing the fault. Radial fluctuation of braid point position is a good indicator of mechanical faults of the tensioning mechanisms. Observations based on mechanical and visual methods are also presented as diagnostic tools. From visual observations, it can be concluded that as the tension in one yarn increases with each revolution, the radial fluctuation increases until a yarn breaks. From mechanical observations, it can be concluded that the fluctuation in motor speed increases until the point when the yarn breaks. Through this study, braid point motion can be used as a diagnostic for shutting down the machine before irreversible damage occurs.

The Design, Analysis And Fabrication Of A Large Cantilevered Composite Boom.

Lawrence, Jeffrey M., Scott T. Holmes, Thomas McKeown, and Vince Keenan. “The Design, Analysis And Fabrication Of A Large Cantilevered Composite Boom.” In Material and Process Innovations: Changing Our World; Sampe Symposium, Long Beach, California, May 18-22, 2008. Covina, CA: Society for the Advancement of Material and Process Engineering, 2008.

SUMMARY

An existing market in the field of electrical scanning equipment has been the use of a doubly-supported boom, holding an antenna at its mid-span. While this design is structurally sound, logistical issues arise with coordinating the two positioning motors. Additionally, in the event of one motor’s failure, the boom would be catastrophically damaged in the process. Therefore a new approach proposes the use of a single cantilevered beam which would require the use of a single positioning motor. The challenge is that while the logistical issues are alleviated, a structural challenge is created. The boom is now subject to the loading of its own body forces as much as that of the antenna, and so there is a demand to lighten the boom. For this reason, this new generation of boom is made from carbon fiber. The stiffness and low density characteristics provide for a good solution. In this work, the design and analysis of the boom will be demonstrated. Further, details of some of the unique fabrication challenges are discussed. By using composite materials, a low weight, high stiffness boom was able to accomplish the goal of moving from a doubly controlled positioning arm to a singly controlled one.

Microstructural Modeling of Three-Dimensional Woven Fiber Composites.

Nicosia, M., F. Vineis, Jeffrey M. Lawrence, and Scott T. Holmes. “Microstructural Modeling of Three-Dimensional Woven Fiber Composites.” In TEXCOMP 9 Recent Advances in Textile Composites: October 13-15, 2008, University of Delaware, John M. Clayton Hall, Newark, Delaware, USA. edited by Suresh G. Advani and John W. Gillespie. Lancaster, PA: DEStech Publications, 2008.

SUMMARY

Composite materials are very attractive relative to metals for aerospace applications for various reasons, including weight savings, favorable thermal and acoustic properties, and corrosion resistance, among others. Three-dimensional woven fiber composite materials have the potential to be superior to the traditional unidirectional and laminate composites in terms both mechanical properties and cost-effectiveness in manufacturing. However, the use of these three-dimensional woven composite materials has been hampered by the absence of appropriate tools to predict stress and failure responses of composite components. The largest challenge in this type of modeling is the disparity in relevant length scales between the unit cell dimension and size of a typical part. To address this issue, microstructural models are used, in which the unit cell geometry is used to predict average macroscopic material properties, which can then be used to perform a stress analysis on the part of interest. Prediction of mechanical failure, however, requires knowledge of the local stress-information generally not available using averaged properties. The goal the current work is to develop a computationally feasible microstructural model for three-dimensional woven composite materials that is capable of resolving local stresses at the level of the unit cell. In general, the multi-scale model consists of two steps: (1) Pre-processing, in which finite element modeling of unit cells is used to estimate the effective material coefficients; and (2) Simulation, in which these effective material properties are used in standard finite element modeling of the component. As the simulation progresses, regions with high stresses are identified, and the unit-cell finite element model is utilized to predict the local stress within the fiber and matrix. This step is accomplished by projecting the macroscopic strain field onto the level of the unit cell to be used as boundary conditions. Preliminary simulations and future directions will be discussed.

Flow simulations and process monitoring to guide advanced VaRTM manufacturing of large complex composite structures.

Lawrence, Jeffrey M., Scott T. Holmes, Michael Louderback, Addison Williams, Pavel Simacek, and Suresh G. Advani. “Flow simulations and process monitoring to guide advanced VaRTM manufacturing of large complex composite structures.” In Sampe Fall Technical Conference and Exhibition: From Art to Science, Advancing Materials & Process Engineering: October 29-November 1, 2007, Cincinnati Hilton Netherland Plaza, Cincinnati, Ohio. Covina, CA: Society for the Advancement of Material and Process Engineering, 2007.

SUMMARY

The Vacuum Assisted Resin Transfer Molding process has gained popularity due to the affordable parts that have been made. The complexity and quality in these parts is now approaching that found in traditional aerospace processes. However, the progression of the resin through the mold is complex and was historically not well understood. Therefore, traditionally a trial and error approach was used based on a foundation of tribal knowledge to produce composite parts of good quality. For this reason, during the past decade, significant academic research has been applied to advanced processing techniques for composite materials manufacturing. One main research thrust has been the simulation of the resin progression through the fibrous preform. This approach enables understanding of how the resin flows through the mold, and reduces the trial and error approach to infusion design. A second area of research has been on-line monitoring of the infusion process. By collecting resin mass-flow data during the infusion, it allows for both a validation of the numerical predictions as well as a quality measure from part to part. In this work, flow simulations were carried out to design an injection scheme which was applied to a real world composite component, a representative helicopter fairing. In-process monitoring was used to validate the predictions of the simulation.