An Energy-Based Concept for Yielding of Multidirectional FRP Composite Structures Using a Mesoscale Lamina Damage Model

Abstract

Composite structures are made of multidirectional (MD) fiber-reinforced polymer (FRP) composite laminates, which fail due to multiple damages in matrix, interface, and fiber constituents at different scales. The yield point of a unidirectional FRP composite is assumed as the lamina strength limit representing the damage initiation phenomena, while yielding of MD composites in structural applications are not quantified due to the complexity of the sequence of damage evolutions in different laminas dependent on their angle and specification. This paper proposes a new method to identify the yield point of MD composite structures based on the evolution of the damage dissipation energy (DDE). Such a characteristic evolution curve is computed using a validated finite element model with a mesoscale damage-based constitutive model that accounts for different matrix and fiber failure modes in angle lamina. The yield point of composite structures is identified to correspond to a 5% increase in the initial slope of the DDE evolution curve. The yield points of three antisymmetric MD FRP composite structures under flexural loading conditions are established based on Hashin unidirectional (UD) criteria and the energy-based criterion. It is shown that the new energy concept provides a significantly larger safe limit of yield for MD composite structures compared to UD criteria, in which the accumulation of energy dissipated due to all damage modes is less than 5% of the fracture energy required for the structural rupture.

Linear-Nonlinear Stiffness Responses of Carbon Fiber-Reinforced Polymer Composite Materials and Structures: A Numerical Study

“…The maximum elastic behavior is concluded in the yielding point ( , ) which represents the onset of damage and depends to the six strength properties of matrix and fiber in tension and compression loading conditions (Equations (2a)–(2d)) [ 35 , 42 , 43 ]. Then, a second linear line ( AB ) representing the damage evolution process to fracture ( ) that is calculated based on fracture energy value in each different failure modes (Equations (4a)–(4d)) [ 1 , 34 , 44 , 45 ]. These mechanical properties are essential to compute a full elastic-to-failure process at material point, that are obtained through standard test processes [ 33 ].…”

Fabrication of High-Quality Polymer Composite Frame by a New Method of Fiber Winding Process

“…The fiber arrangement in normal composites would result the fibers as the load-bearing core component of the composite, to sustain the load, and ensure the composite frame to bear the designed load before fracture. The process of damage in normal composites occurs gradually, and composite structures are normally able to sustain severe loading conditions [54,55]. However, due to the inconsistent fiber arrangement in composite frame made by manual-robot winding, and stress concentration phenomena at curved sections as well as the matrix pocket parts, the material damage that initiate as matrix micro-crack would easily shift to cross-sectional fracture of the frame at the matrix pocket locations.…”

“…In this condition, due to the very low properties of matrix materials in comparison with the fiber properties (10%), it is expected that each ply could only sustain about 10% of the load-share assumed for the composite ply. This excessively diminish the yielding limit and desired tolerance of the composite frame [6,53,55,56].…”

Investigation on the Curvature Correction Factor of Extension Spring

“…This research was a numerical study, considering displacement instead of force to apply deformation results in a smooth convergence, as the FE-based model initially calculated deformation of the structure and subsequently computed the force parameters. Such an assumption was considered in many basic studies in the literature [24][25][26]. Remote displacement was chosen instead of the regular displacement condition to allow the part to rotate freely about the Y axis ( Figure 7).…”