Indentation response of a 3D non-woven carbon-fibre composite
- PDF / 1,471,987 Bytes
- 13 Pages / 584.957 x 782.986 pts Page_size
- 76 Downloads / 223 Views
Karthikeyan Kandan Department of Engineering, University of Cambridge, Cambridge CB2 1PZ, U.K.; and School of Engineering, De Montfort University, Leicester LE1 9BH, U.K.
Sohrab Kazemahvazi Department of Engineering, University of Cambridge, Cambridge CB2 1PZ, U.K.
Haydn N.G. Wadley Department of Material Science & Engineering, School of Engineering and Applied Science, University of Virginia, Charlottesville, Virginia 22904, USA
Vikram S. Deshpandea) Department of Engineering, University of Cambridge, Cambridge CB2 1PZ, U.K. (Received 4 October 2017; accepted 8 December 2017)
The indentation response of a 3D noninterlaced composite comprising three sets of orthogonal carbon-fibre tows in an epoxy matrix is investigated. The 3D composites have a near isotropic and ductile indentation response. The deformation mode includes the formation of multiple kinks in the tows aligned with the indentation direction and shearing of the orthogonally oriented tows. Finite element (FE) calculations are also reported wherein tows in one direction are explicitly modeled with the other two sets of orthogonal tows and the matrix pockets treated as an effective homogenous medium. The calculations capture the indentation response in the direction of the explicitly modeled tows with excellent fidelity but under-predict the indentation strength in the other directions. In contrast to anisotropic and brittle laminated composites, 3D noninterlaced composites have a near isotropic and ductile indentation response making them strong candidates for application as materials to resist impact loading.
I. INTRODUCTION
Composite materials such as carbon fiber reinforced polymer (CFRP) composites made by laminating unidirectionally reinforced plies are extensively used in civil and aircraft structures due to their high specific strength and stiffness, superior corrosion resistance and improved fatigue resistance compared to conventional engineering materials such as aluminum and steel.1–3 However, such materials are susceptible to interply delamination,4,5 which traditionally has limited their use in situations, where impact loading can occur. Nevertheless, lightweighting programs for transportation structures are driving renewed interest in composite materials for impact protection systems. For example, military vehicles are required to resist projectile impacts while in civilian aircraft applications the engines and airframes must be able to resist impacts from hail, bird strikes and impact by other foreign objects. In most cases, the structure needs to
Contributing Editor: Lorenzo Valdevit a) Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/jmr.2017.481
be able to retain its structural integrity after impact loading, which presents a serious challenge for traditional laminated composites. Impact loads induce a range of damage modes in composites that seriously degrade their mechanical performance. These damage modes include matrix cracks, delamination between plies and fiber fracture. Delamination under impact l
Data Loading...
