3D Printed Cement Structural Elements with Complementary Shear Keys
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Solution Overview
Problem
The challenge in 3D printing of cementitious structural elements is achieving precise dimensional tolerances and mechanical resistance, particularly in large structures like bridges and towers, where traditional methods fail to ensure accurate assembly and may require costly rectification and shim insertion due to difficulties in adjusting the position of elements during assembly.
Innovation Solution
A method involving the 3D printing of structural elements with complementary facing faces, including reliefs such as shear keys, to facilitate precise assembly and mechanical strength, using a 3D printing device with a robot and computer-controlled deposition of cementitious material, allowing for the separation of elements without damage and ensuring accurate alignment and bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If 3D printing is used to manufacture structural elements, then complex structures can be fabricated and productivity is improved, but manufacturing precision and dimensional tolerances deteriorate
Solution Approach 1:
The structure is divided into multiple structural elements that are manufactured separately and then assembled. This segmentation allows each element to be produced with controlled tolerances while maintaining the capability to fabricate complex overall structures through 3D printing.
Solution Approach 2:
Complementary reliefs (protrusions and recesses) are pre-formed on the facing faces of structural elements during the 3D printing process. This preliminary action ensures that when elements are assembled, the reliefs automatically align and bond the elements together, compensating for tolerance variations and eliminating the need for post-manufacturing rectification.
2Manufacturing precision
If traditional rectification methods are implemented to meet dimensional tolerances, then manufacturing precision is improved, but loss of time and device complexity increase
Solution Approach 1:
The complementary reliefs are formed during the initial 3D printing process rather than requiring subsequent machining operations. This preliminary action eliminates time-consuming rectification steps while maintaining the required dimensional tolerances for assembly.
3Manufacturing precision
If high-precision machining is performed on structural element faces, then manufacturing precision is improved, but loss of substance and use of energy increase
Solution Approach 1:
The complementary reliefs are created directly during the additive 3D printing process, eliminating the need for subtractive machining operations. This approach prevents material removal and waste while achieving the precise geometric features needed for assembly.
4Manufacturing precision
If precise adjustments are made during assembly to maintain tolerances, then manufacturing precision is improved, but ease of operation deteriorates
Solution Approach 1:
The complementary reliefs are pre-formed on the facing faces of structural elements during manufacturing. During assembly, these reliefs automatically align and bond the elements together, eliminating the need for complex precise adjustments on-site and greatly simplifying the assembly operation.
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 method enhances control over manufacturing tolerances, reduces the need for grinding operations, and improves mechanical strength by ensuring precise alignment and bonding of structural elements, leading to a structure that meets planned dimensional requirements.
Implementation Method 1
3D printing techniques employ a system comprising a robot with an articulated arm equipped with a printing nozzle at its end... depositing beads of fresh cementitious material in successive layers
Implementation Method 2
It allows for monitoring the setting, curing, shrinkage, and creep of the cementitious material
Implementation Method 3
It allows for monitoring the setting, curing, shrinkage, and creep of the cementitious material
Data Source
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AI summary
A method for producing a plurality of structural elements, with a view to forming after assembly at least a part of a structure (195) in cementitious material, the method comprising: a) the production of a first structural element (105) comprising the 3D printing of a first body (70) in cementitious material, b) the production of a second structural element (155) in contact with the first structural element, comprising the 3D printing of a second body (160) in cementitious material, the first and second structural elements having opposite faces, respectively called "first face" (125) and "second face" (170), of complementary shapes, and c) the separation of the first and second structural elements.