3D Patterned Energy Absorptive Material Fabrication
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Solution Overview
Problem
Current methods for fabricating cellular silicone foams are lengthy, difficult, and result in non-optimal material structures due to high viscosity, shear-induced mechanical degradation, and incomplete cure, with limited ability to achieve density variations or gradations, making them unsuitable for energy absorbing applications that require tailored bulk properties.
Innovation Solution
A three-dimensionally patterned energy absorptive material is created through layer-by-layer extrusion-formation and curing of patterned filaments, allowing for controlled bulk properties and tailored architectures, including open and closed cells, uniform or graded properties, and non-planar surface contours, using an additive extrusion-based process like direct ink write to achieve desired mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If cellular silicone foam fabrication process is used, then energy absorbing material can be produced, but the process is long (about six weeks) and difficult
Solution Approach 1:
The fabrication process is segmented into discrete layers that are extruded and stacked sequentially. Each layer is formed independently through extrusion of precursor material through a patterning die, allowing parallel processing of multiple layers and significantly reducing overall fabrication time compared to traditional monolithic foam processes.
Solution Approach 2:
The traditional mechanical mixing and molding processes are replaced with extrusion-based direct writing. The precursor material is extruded through a patterning die to directly form the desired structure, eliminating complex mechanical mixing steps and reducing process difficulty.
2Strength
If traditional cellular silicone fabrication is used, then material can be produced, but mechanical degradation occurs due to high viscosity and shear causing chain scission
Solution Approach 1:
High-shear mechanical mixing is replaced with low-shear extrusion through a patterning die. The precursor material flows through the die under controlled pressure, minimizing shear forces and preventing chain scission while still achieving the desired patterned structure.
Solution Approach 2:
The processing parameters are changed to operate at lower shear rates and controlled temperatures during extrusion. This modifies the flow conditions to prevent mechanical degradation of the precursor material while maintaining pattern fidelity.
3Reliability
If cellular silicone foam fabrication is used, then material can be produced, but incomplete cure occurs due to urea inhibition
Solution Approach 1:
The curing process is segmented and applied layer-by-layer as each extruded layer is deposited. This allows sufficient cure time for each layer before the next is added, preventing urea inhibition issues that occur when thick sections are cured simultaneously.
Solution Approach 2:
The precursor material is pre-patterned through the extrusion die before curing occurs. This allows the structure to be defined in its uncured state, then cured in place, avoiding the need to cure thick sections simultaneously which causes urea inhibition.
4Adaptability or versatility
If cellular foam fabrication is used, then material can be produced, but density variations or gradations are difficult to achieve
Solution Approach 1:
Different density regions are created by varying the extrusion parameters (flow rate, temperature, die geometry) for different spatial locations. The patterning die can be designed with varying aperture sizes or the extrusion conditions can be adjusted locally to achieve graded density distributions throughout the material.
Solution Approach 2:
The extrusion parameters (temperature, pressure, flow rate, die geometry) are varied to control the density of different regions. By changing these parameters during the extrusion process, precise control over density uniformity or gradation is achieved.
5Manufacturing precision
If cellular silicone foam is used, then material can be produced, but pores are too large for some applications
Solution Approach 1:
The pore size is controlled by changing the extrusion parameters including die aperture dimensions, extrusion rate, and precursor material viscosity. These parameters can be adjusted to produce pore sizes ranging from micrometers to millimeters, expanding the range of applicable uses.
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 the production of materials with predictable and tailored bulk properties, improved mechanical response, reduced processing time, and longer component life, suitable for various energy absorption applications by allowing for customized structures and properties.
Implementation Method 1
curing the multiple layers of patterned filaments so that the energy absorptive material produced thereby has a desired bulk property
Data Source
AI summary
A three-dimensionally patterned energy absorptive material and fabrication method having multiple layers of patterned filaments extrusion-formed from a curable pre-cursor material and stacked and cured in a three-dimensionally patterned architecture so that the energy absorptive material produced thereby has an engineered bulk property associated with the three-dimensionally patterned architecture.