Effects of Material Nonlinearities on Design of Composite Constructions-Elasto-Plastic Behaviour

Area of Science:

• Materials Science
• Mechanical Engineering
• Structural Analysis

Background:

• Traditional composite structure design often relies solely on linear elastic analysis.
• Experimental data indicates that both unidirectional and woven roving composites exhibit physical non-linear behavior.
• This non-linearity is primarily attributed to micromechanical damage, such as matrix cracking, which can be modeled using elastic-plastic relationships.

Purpose of the Study:

• To investigate the influence of both physical and geometrical non-linearities on the limit states of composite structures.
• To analyze the behavior of composite pressure vessel components, specifically cylindrical shells and shell junction reinforcements.
• To formulate and solve an optimization method for reinforcement thickness.

Main Methods:

• Incorporation of physical non-linearities, including matrix cracking modeled with elastic-plastic relations.
• Inclusion of geometrical non-linearities in the analysis.
• Numerical simulations of composite pressure vessel components (cylindrical shell, shell junction).
• Development and application of an optimization method for reinforcement thickness.

Main Results:

• Experimental validation of physical non-linear behavior in composite materials.
• Demonstration of the significant impact of combined physical and geometrical non-linearities on composite structure limit states (buckling, failure/damage).
• Successful application of numerical examples to composite pressure vessel components.

Conclusions:

• Advanced analysis considering both physical and geometrical non-linearities is crucial for accurate composite structure design.
• The study provides insights into the failure mechanisms and limit states of composite pressure vessels.
• An effective optimization method for reinforcement thickness in composite structures has been developed and validated.