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Geometry investigation of highly reconfigurable periodic surfaces.
A new approach that combines a pre-stressed textile with a fiber reinforced polymer (FRP) shell structure is currently investigated at CMASLab. This method allows the realization of periodic structures whose mechanical properties will be investigated in this thesis.
**Motivation**
Variable stiffness and multi-stable laminates for deployable structures are increasingly receiving attention. One of the most important characteristics is that multi-stable laminates can generate large changes of shapes without the need for a continuous power supply. In this horizon, a new approach that combines a pre-stressed textile with a fiber reinforced polymer (FRP) shell structure is currently investigated at CMASLab.
This approach allows manufacturing structures that show out of plane curvatures with a 2D bonding process. In particular, a square frame structure has been proved to show 8 stable modes. Another result shows that with the use of modularity, a wavy grid surface can be manufactured. A FE analysis has been conducted on the single cells structure but the behavior of the period structures has not been characterized yet. The student will generate a reliable FE model and validate it with experiments.
**Thesis Objectives**
The concept was investigated on a unit cell level and current research is done on periodic metamaterial geometries. The preliminary unit cell investigation, performed on a frame-like composite shell bonded together with a bi-axially pre-stretched membrane, demonstrates that such structures possess several stable modes. The shell is manufactured on a flat plate by employing a symmetric layup of thin carbon fiber prepreg material. The shape-forming mechanism arises when the energy that is pre-stored in the membrane is released -- the thin composite frame buckles and a saddle like shape is generated. The frame possess eight stable modes; four of which are a result of symmetry. The periodic rearrangement of such a geometry results in a surface that has several stable modes. In the first part of his research, the student will investigate with experiments other geometries for the single cell (i.e. hexagon, triangle, etc.). Given an already exiting code for the shape-forming prediction of the square-like structure, the stude
**Motivation** Variable stiffness and multi-stable laminates for deployable structures are increasingly receiving attention. One of the most important characteristics is that multi-stable laminates can generate large changes of shapes without the need for a continuous power supply. In this horizon, a new approach that combines a pre-stressed textile with a fiber reinforced polymer (FRP) shell structure is currently investigated at CMASLab.
This approach allows manufacturing structures that show out of plane curvatures with a 2D bonding process. In particular, a square frame structure has been proved to show 8 stable modes. Another result shows that with the use of modularity, a wavy grid surface can be manufactured. A FE analysis has been conducted on the single cells structure but the behavior of the period structures has not been characterized yet. The student will generate a reliable FE model and validate it with experiments.
**Thesis Objectives** The concept was investigated on a unit cell level and current research is done on periodic metamaterial geometries. The preliminary unit cell investigation, performed on a frame-like composite shell bonded together with a bi-axially pre-stretched membrane, demonstrates that such structures possess several stable modes. The shell is manufactured on a flat plate by employing a symmetric layup of thin carbon fiber prepreg material. The shape-forming mechanism arises when the energy that is pre-stored in the membrane is released -- the thin composite frame buckles and a saddle like shape is generated. The frame possess eight stable modes; four of which are a result of symmetry. The periodic rearrangement of such a geometry results in a surface that has several stable modes. In the first part of his research, the student will investigate with experiments other geometries for the single cell (i.e. hexagon, triangle, etc.). Given an already exiting code for the shape-forming prediction of the square-like structure, the stude
The goal of the thesis is to investigate if the choice of selected periodic structures allows the manufacturing of a reconfigurable surface that can potentially show several stable state
The work will be subdivided in the following tasks:
• literature research;
• Task 1: manufacturing of other single cell geometries;
• Task 2: mechanical characterization (tensile modulus and poisson’s ratio) of the TPU thin foil;
• Task 3: FE modelling of the new single cell geometries and model validation;
• Task 4: experimental investigation of the periodic surface multi-stability behaviour.
The goal of the thesis is to investigate if the choice of selected periodic structures allows the manufacturing of a reconfigurable surface that can potentially show several stable state The work will be subdivided in the following tasks: • literature research; • Task 1: manufacturing of other single cell geometries; • Task 2: mechanical characterization (tensile modulus and poisson’s ratio) of the TPU thin foil; • Task 3: FE modelling of the new single cell geometries and model validation; • Task 4: experimental investigation of the periodic surface multi-stability behaviour.