TY - GEN
T1 - Comparing the effect of geometry and stiffness on the effective load paths in non-symmetric laminates
AU - Minera Rebulla, Sergio A.
AU - Patni, Mayank
AU - Weaver, Paul M.
AU - Pirrera, Alberto
AU - O’donnell, Matthew P.
N1 - Publisher Copyright:
© 2019, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.
PY - 2019
Y1 - 2019
N2 - In aerospace composite material design, it is common to encounter load bearing components that vary in thickness across their length. In plate design, ply drops, tow-steering, and the addition of stiffeners, all act to change both the section geometry and the effective stiffness of the part. Often, due to aerodynamic design constraints, the geometric profile must transition non-symmetrically, i.e. thickness is built up from a reference surface, meaning the mid-surface of the plate does not remain on a constant plane. These localised changes in geometry, and associated change of position of the mid-surface, lead to inherently three-dimensional states of stress. As a consequence, and especially for composite structures, there is the potential for significant through-thickness stresses and/or stress concentrations, leading to failure—for example debonding or delamination. By investigating the effects of geometric and effective stiffness changes, we are able to gain physical insight into structural behaviour in the regions of geometric transition. This is achieved through a parametric study, whereby we compare the behaviour as predicted by Classical Laminate Theory—a commonly utilised two-dimensional approach—with a finite element analysis based on the Unified Formulation by Carrera and co-workers. Based on these investigations, we are able to illustrate how rates of profile change and/or stiffness variation are linked to variance in the predicted location of the neutral plane of the two approaches which acts as a proxy measure for predicting through-thickness behaviour. Finally, we discuss the potential opportunity to utilise laminates that possess non-standard layups to tailor the load path through geometric transitions, thus offering a potential route for elastic tailoring that minimises undesirable through-thickness stresses.
AB - In aerospace composite material design, it is common to encounter load bearing components that vary in thickness across their length. In plate design, ply drops, tow-steering, and the addition of stiffeners, all act to change both the section geometry and the effective stiffness of the part. Often, due to aerodynamic design constraints, the geometric profile must transition non-symmetrically, i.e. thickness is built up from a reference surface, meaning the mid-surface of the plate does not remain on a constant plane. These localised changes in geometry, and associated change of position of the mid-surface, lead to inherently three-dimensional states of stress. As a consequence, and especially for composite structures, there is the potential for significant through-thickness stresses and/or stress concentrations, leading to failure—for example debonding or delamination. By investigating the effects of geometric and effective stiffness changes, we are able to gain physical insight into structural behaviour in the regions of geometric transition. This is achieved through a parametric study, whereby we compare the behaviour as predicted by Classical Laminate Theory—a commonly utilised two-dimensional approach—with a finite element analysis based on the Unified Formulation by Carrera and co-workers. Based on these investigations, we are able to illustrate how rates of profile change and/or stiffness variation are linked to variance in the predicted location of the neutral plane of the two approaches which acts as a proxy measure for predicting through-thickness behaviour. Finally, we discuss the potential opportunity to utilise laminates that possess non-standard layups to tailor the load path through geometric transitions, thus offering a potential route for elastic tailoring that minimises undesirable through-thickness stresses.
UR - http://www.scopus.com/inward/record.url?scp=85088067974&partnerID=8YFLogxK
U2 - 10.2514/6.2019-1766
DO - 10.2514/6.2019-1766
M3 - Conference contribution
AN - SCOPUS:85088067974
SN - 9781624105784
T3 - AIAA Scitech 2019 Forum
BT - AIAA Scitech 2019 Forum
PB - American Institute of Aeronautics and Astronautics Inc, AIAA
T2 - AIAA Scitech Forum, 2019
Y2 - 7 January 2019 through 11 January 2019
ER -