Modelli di impatto a bassa velocità di laminati in materiale composito
Autore
Pier Francesco Orru - Università degli Studi di Cagliari - [1998-99]
Documenti
Abstract
In this study an improved spring-mass model is developed to calculate the contact force history during low velocity impacts on composite plates. It includes the influence of damping effects on the contact area and can take into account fibre fracture or other damage events with appropriate modifications of the relevant parameters.
The model describes the impactor and the target laminate by two rigid masses, while the contact interaction is represented by a Hertzian spring and a non linear viscous damper and the deformation behaviour of the laminate by a combination of bending and membrane springs.
To incorporate major damage events in the model, the bending and membrane stiffness of the composite plate may be reduced, after reaching a critical load, to account for the degradation of the material associated to the progression of broken fibres. In this case, the reduced stiffness values introduced in the model were obtained by post-failure FEM calculations as a function of contact force and extension of fibre fracture.
Comparisons between experimental and numerical results are shown to confirm the efficiency and accuracy of the model in correctly describing the dynamics of the impact event, even in the presence of dissipative effects such as damping, frictional losses or fracture phenomena.
The model describes the impactor and the target laminate by two rigid masses, while the contact interaction is represented by a Hertzian spring and a non linear viscous damper and the deformation behaviour of the laminate by a combination of bending and membrane springs.
To incorporate major damage events in the model, the bending and membrane stiffness of the composite plate may be reduced, after reaching a critical load, to account for the degradation of the material associated to the progression of broken fibres. In this case, the reduced stiffness values introduced in the model were obtained by post-failure FEM calculations as a function of contact force and extension of fibre fracture.
Comparisons between experimental and numerical results are shown to confirm the efficiency and accuracy of the model in correctly describing the dynamics of the impact event, even in the presence of dissipative effects such as damping, frictional losses or fracture phenomena.
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