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.