Variable Stiffness Structure Using Segmented Layers
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Solution Overview
Problem
Current structural materials face limitations in achieving large, reversible changes in shape and stiffness due to their linear elastic properties, which restricts their ability to adapt to various operational conditions and requires complex assemblies for reconfiguration, especially in applications like aerospace and morphing structures.
Innovation Solution
A variable stiffness structure composed of alternating layers of constant stiffness material and variable modulus material, where the latter changes its elastic modulus in response to energy fields, allowing for reversible coupling and decoupling of stress transfer between layers to adjust bending stiffness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If linear elastic materials are used for structural components, then the structure maintains high stiffness and strength, but the capability for large reversible deformation and shape change is severely limited
Solution Approach 1:
The structure is divided into multiple layers with alternating properties: linear elastic layers (providing strength and stiffness) and active material layers (enabling deformation). This segmentation allows each layer type to perform its specialized function while contributing to the overall structural performance.
Solution Approach 2:
The invention creates a composite structure combining linear elastic materials with active materials that can reversibly change stiffness. This composite approach integrates the advantages of both material types: the structural integrity of linear elastic materials and the adaptive deformation capability of active materials.
2Strength
If the structure is designed for high stiffness, then structural strength is improved, but the energy required for deformation increases significantly and reversible deformation capability is limited
Solution Approach 1:
By segmenting the structure into stiff linear elastic layers and compliant active material layers, the energy required for deformation is reduced. The active material layers can reversibly deform with lower energy input while the linear elastic layers maintain structural strength, avoiding the need to deform the entire high-stiffness structure.
Solution Approach 2:
The active material layers can reversibly change their stiffness parameter in response to external stimuli. This parameter change allows the structure to transition between high-stiffness (energy-efficient for maintaining shape) and low-stiffness (energy-efficient for deformation) states, optimizing energy usage.
3Adaptability or versatility
If active material components are attached to linear elastic materials, then adaptive actuation capability is achieved, but significant change in shape and form is hampered
Solution Approach 1:
The structure is segmented into alternating layers of linear elastic material and active material, allowing both materials to work together in a coordinated manner. This layered segmentation enables the active material to induce shape changes while the linear elastic material provides structural support, achieving both adaptive actuation and significant shape change.
Solution Approach 2:
The composite layered structure integrates linear elastic materials with active materials that can reversibly change stiffness. This composite design overcomes the limitations of attaching active materials to linear elastic materials by creating a unified structure where both material types contribute to the overall shape change capability.
4Adaptability or versatility
If traditional mechanical components (pivots, latches) are used for deployable structures, then structural reconfiguration is achieved, but weight and device complexity increase
Solution Approach 1:
The invention extracts and eliminates traditional mechanical components (pivots, latches, fasteners) from deployable structures. Instead, it uses the intrinsic variable stiffness properties of the layered material structure to enable reconfiguration, significantly reducing the number of parts and assembly complexity.
Solution Approach 2:
The patent replaces mechanical systems (pivots, latches, mechanical joints) with a material-based system utilizing variable stiffness layers. The reconfiguration is achieved through controlled changes in the stiffness of active material layers rather than through mechanical component movement and assembly.
5Use of energy by moving object
If variable stiffness structures are used for morphing applications, then significant changes in bending stiffness and shape are achieved with reduced energy requirements, but the structure requires materials that can reversibly change elastic modulus in response to energy fields
Solution Approach 1:
The invention uses composite materials combining linear elastic materials with active materials that can reversibly change stiffness in response to external energy fields. This composite approach enables variable stiffness functionality while utilizing materials that are increasingly available through advances in smart material technology.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables significant changes in bending stiffness and shape with reduced energy requirements, allowing for lightweight, complex morphing structures that can adapt to multiple operational conditions without the need for additional components, achieving stiffness comparable to traditional structural materials.
Implementation Method 1
The variable modulus material layers have a material with a changeable elastic modulus in response to an applied energy field
Data Source
AI summary
In some embodiments, a variable stiffness structure is provided having constant stiffness material layers and variable modulus material layers arranged in alternating layers. The variable modulus material layers have a material with a changeable elastic modulus in response to an applied energy field so as to allow reversible coupling and decoupling of stress transfer between successive layers of the constant stiffness material layers to provide a change in a bending stiffness of the variable stiffness structure. The constant stiffness material layers may include segmented portions. The constant stiffness material layers may have segmented portions arranged such that successive layers of the plurality of constant stiffness material layers have overlapping segmented portions. The variable modulus material layers may have shaped structures, for example, corrugation, pillars, striations, tubular, or honeycomb configurations.