Johannes Reiner

Experimental and numerical analysis of drop-weight low-velocity impact tests on hybrid titanium composite laminates:

An experimental and numerical study on low-velocity impact responses on [Ti/0/90] s hybrid titanium composite laminates (HTCLs) is presented. Different energy levels from 10 to 40 J are investigated using a drop-weight instrument and post-impact inspection. An explicit finite element implementation provides a detailed analysis of impact response in composite and titanium layers, respectively. It accounts for interfacial debonding, progressive failure in composite plies and elastic–plastic deformation in titanium. The main failure modes are experimentally and numerically found to be debonding between titanium and composite, matrix cracking and interlaminar delamination. The principal energy-absorbing mechanism is plastic dissipation of the two titanium sheets. The low cost numerical model is able to effectively predict the overall impact response and major failure modes with good accuracy.

A progressive analysis of matrix cracking-induced delamination in composite laminates using an advanced phantom node method

Matrix cracking-induced delamination in composite laminates is qualitatively and quantitatively investigated in a finite element framework. The phantom node method is extended to incorporate breakable interfaces at transverse matrix crack tips. New user-defined element types in Abaqus improve the numerical stability in a geometrically nonlinear analysis. The new formulation allows for accurate prediction of matrix crack density and stiffness reduction in a number of composite laminates. Furthermore, the advanced phantom node method is able to simulate progressive matrix cracking-induced delamination with good accuracy.

8.4 Structural Analysis of Composites With Finite Element Codes: An Overview of Commonly Used Computational Methods

Computational methods and simulations have become an essential part of design and analysis of composite materials and structures . Virtual testing of real composite structures can not only reduce physical testing, but also offers cost-effective design flexibility. This chapter provides a comprehensive review and guidelines on a range of finite element (FE) modeling techniques that are currently being used for composite materials including the simulations performed at different length and time scales as well as techniques to incorporate damage initiation and evolution. Capabilities of the most commonly used commercial FE software packages are discussed and current trends and latest developments in the field are presented.

Failure Modes in Hybrid Titanium Composite Laminates

Hybrid titanium composite laminates (HTCLs) combine the benefits of thin titanium sheets and fiber-reinforced polymer (FRP) composite laminates to design high performance light-weight materials with optimized impact resistance, fracture toughness, durability, and/or thermal performance. This paper starts with a detailed review of typical failure modes observed in HTCLs. The critical manufacturing process of thin grade II titanium sheets combined with HexPly G947/M18 carbon fiber-reinforced polymer laminates is described in detail. This includes the evaluation of titanium surface preparation techniques, which guarantee good adhesive bonding. A systematic experimental study of different HTCL configurations under tensile loading confirms that the major failure modes are debonding between the titanium sheet and the FRP laminate, matrix cracking in the 90 deg plies of the FRP laminate and interlaminar delamination. The results show that HTCLs made from woven carbon FRP plies show higher ultimate strengths and strain at breaks than HTCLs containing a cross-ply composite core made from unidirectional (UD) prepreg.