3D Printed Structures Optimized for Worst-Case Loads
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Solution Overview
Problem
Large-scale 3D printing technologies, such as binder jetting, face limitations in fabricating strong architectural ornamentation due to the asymmetry in compressive and tensile strengths of build materials, leading to structural weaknesses under realistic loads and moderate stresses.
Innovation Solution
A 3D printer system equipped with a structural optimization tool that optimizes the design of objects by hollowing interiors and varying outer wall thicknesses, accounting for the asymmetry in compressive and tensile strengths using the Bresler-Pister failure criterion, and minimizing material volume while ensuring structural integrity under worst-case loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If binder jetting 3D printing is used to fabricate large-scale objects, then manufacturing capability and geometric freedom are improved, but structural strength under tension deteriorates due to material asymmetry
Solution Approach 1:
The patent applies local quality by varying wall thicknesses throughout the structure based on stress analysis. Thicker walls are placed in regions experiencing higher tensile stresses, while thinner walls are used in compression-dominated or low-stress areas. This non-uniform thickness distribution optimizes structural strength where needed while minimizing material usage in less critical regions, directly addressing the tensile strength weakness of binder jetting materials.
Solution Approach 2:
The patent employs composite materials by combining the binder jetting print material (sand or concrete-like material) with steel reinforcement bars (rebar). The rebar is embedded within the 3D printed structure to specifically address the tensile strength deficiency, creating a composite system where the print material handles compression and the steel handles tension, thereby resolving the material asymmetry problem.
2Weight of moving object
If material volume is reduced to decrease weight, then strength-to-weight ratio is improved, but structural integrity under worst-case loads deteriorates
Solution Approach 1:
The patent applies preliminary action by performing comprehensive stress analysis and structural optimization before the actual 3D printing process. The design software calculates worst-case load scenarios and determines the optimal material distribution and wall thicknesses in advance. This pre-planning ensures that the printed structure achieves maximum structural integrity with minimum material volume, as the design is optimized specifically for the material's compression-tension asymmetry before fabrication begins.
Solution Approach 2:
The patent employs parameter changes by systematically varying wall thickness parameters throughout the structure based on stress distribution analysis. The software adjusts local thickness parameters to match the actual stress demands, creating a structure where material is concentrated in high-stress regions and minimized in low-stress regions. This parameter optimization maintains structural integrity under worst-case loads while minimizing overall material volume and weight.
3Device complexity
If uniform wall thickness is used for simplicity, then manufacturing process is simplified, but material distribution becomes inefficient under asymmetric loads
Solution Approach 1:
The patent applies preliminary action by automatically performing stress analysis and optimal material distribution calculations before printing. The design software handles the complex variable thickness optimization automatically, eliminating the need for manual iterative design. This preliminary computational step produces a print-ready model with optimized variable wall thicknesses, maintaining simplicity in the manufacturing process while achieving superior material efficiency compared to uniform thickness designs.
Data Source
AI summary
A 3D printer system with a structural optimization tool to generate 3D models optimized for build materials such as those used in binder jetting technology-based printers. The structural optimization tool uses a computational approach to optimize mechanical and mass properties of large-scale structures (i.e., objects to be 3D printed), and the computational approach is tailored for fabrication on binder jetting technologies. To spend a material budget for printing an object wisely, the inventors in designing the computational approach turned the Bresler-Pister failure criterion into an objective measuring the potential of failure of an object or structure. This involved modeling the difference in tensile and compressive strength of the build material. To optimize structures under worst-case loads, the computational approach unifies an optimization to identify worst-case loads with an optimization to minimize the resulting failure potential, nesting them with first-order optimality constraints.