Selective Stereolithography for Composite Material Property Variation
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Solution Overview
Problem
Existing stereolithography methods fail to create composite objects with specific, varied material properties throughout, as they produce homogenous composite materials even when fillers like ceramic or metal particles are added to the liquid photopolymer.
Innovation Solution
A computer-controlled apparatus selectively solidifies a liquid curable material and deposits a second material in specific locations, allowing for the formation of composite objects with distinct properties by using a deposition head and an activation head that work in conjunction with robotic arms and energy sources to create core and shell structures with different materials and properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If fillers such as ceramic or metal particles are added to the liquid photopolymer to form a curable suspension, then composite objects can be fabricated, but the resulting object has consistent material characteristics throughout and does not allow specific portions to have specific desired properties
Solution Approach 1:
The patent applies local quality by using a digital light processing system to selectively cure different regions of the liquid photopolymer suspension with varying degrees of precision. The DLP projector can target specific areas with different exposure doses, allowing certain portions of the object to have higher filler concentration or different material properties while other areas maintain the base composition. This enables spatial variation in material characteristics throughout the fabricated object.
Solution Approach 2:
The invention utilizes parameter changes by varying the light exposure parameters (intensity, duration, pattern) during the DLP printing process to control the curing degree and filler distribution in different regions. By adjusting these parameters dynamically, the system can create zones with different material densities, strengths, or other properties, transforming a homogenous curable suspension into a functionally graded composite structure.
2Strength
If stereolithography is used to fabricate composite objects, then objects with specific physical characteristics can be created, but the process produces homogenous composite materials throughout the entire part
Solution Approach 1:
The DLP printing system enables local quality enhancement by selectively applying different curing parameters to different regions of the composite object. This allows critical load-bearing areas to have optimized material properties with higher crosslinking density or filler concentration, while non-critical areas maintain standard composition, thereby achieving variable strength distribution tailored to functional requirements.
Solution Approach 2:
The process employs preliminary action by first creating a green body structure with the curable suspension that contains the desired filler distribution pattern, then selectively curing different regions in subsequent steps. This preliminary structuring allows the material composition to be predetermined before final curing, enabling controlled heterogeneity in the finished composite object.
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
Enables the fabrication of composite objects with tailored properties, such as varying strength and density, by selectively solidifying and depositing materials according to the geometry of the object, allowing for customized material distribution and enhanced performance.
Implementation Method 1
an activation head movable and selectively operable relative to the top surface to selectively solidify portions of the curable first material at the top surface
Data Source
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AI summary
A method for fabricating a composite object with a computer-controlled apparatus, and the apparatus therefor. The comprises a reservoir containing liquid, curable first material, means to selectively solidify the first material and means to selectively deposit a second material. The method involves the steps of selectively depositing portions of the second material, and selectively solidifying portions of the first material, such that the solidified portions of the first material and the deposited portions of the second material form the composite object.