P20652: 3D Concrete Printer

Systems Design

Table of Contents

1 Team Vision for System-Level Design Phase
2 Systems Design Review Materials
3 Functional Decomposition
4 Systems Architecture
5 Benchmarking
6 Concept Development and Morphological Chart
7 General Feasibility: Prototyping, Analysis, Simulation
8 Focused Feasibility: Prototyping, Analysis, Simulation
9 Concept Selection
10 Pugh Charts
11 Final Concept Selection and Morphological Chart
12 Risk Assessment
13 Preliminary Test Plan
14 Plans for Next Phase

Team Vision for System-Level Design Phase

We plan to formulate a system architecture while putting forth the best effort to complete tasks correctly the first time. Efficient use of people, resources and time will allow the team to improve performance.

A functional decomposition was created in order to determine the functions that the 3D concrete printer will need to achieve. Other currently available 3D concrete printers were benchmarked. Next, concepts were generated to complete the functions generated from the functional decomposition. We selected concepts that will be implemented in the final solution. Block diagrams were created to detail how the 3D concrete printer will work.

Systems Design Review Materials

Based upon feedback from our Problem Definition Design Review, we will be presenting directly from the EDGE website. By doing this, full documents can be reviewed by the Guide, Customer, and audience as opposed to excerpts of documents or links out of a presentation as found in PowerPoints. The presentation agenda and pre-read can be found here. In addition, the Customer and Guide were also linked to the systems design page prior to the presentation.

Functional Decomposition

The first step in a system level design is to determine what the resulting product or service needs to be able to do, and how it will achieve that. For team P20652, this includes the functions of a 3D concrete printer.

Functional Decomposition.

Systems Architecture

To represent the system architecture of the 3D printer, block diagrams were used. Three separate block diagrams were created with three different levels of detail.

Simple Block Diagram of Design.

More Detailed Block Diagram of Design.

Benchmarking

In order to understand and create a realistic scope for our 3D printer, research was done into other 3D concrete printing solutions. Since the mixture of the printed material as well as the machine are within the scope of our project, separate benchmarking documents were generated for each category.

Machine benchmarking was done based on many commercially available and research phase 3D printers. The excel document containing the complete machine benchmarking document can be found here.

Latest Benchmarking of Machine.

Mixture benchmarking was done based upon previous 3D concrete printing projects with publicly available mixture information. Additionally, there are some detailed research papers done on the optimal concrete for 3D printing. The excel document containing the complete mixture benchmarking documents can be found here.

Latest Benchmarking of Mixture.

Concept Development and Morphological Chart

Concept development was done through brainstorming and research. Several concepts were generated for a variety of machine subsystems. Potential concepts for 8 categories were collected into a Morphological Chart. The Morphological Chart is shown below.

Latest Morphological Chart

General Feasibility: Prototyping, Analysis, Simulation

These documents pertain to feasibility analyses performed prior to the concept selection tasks began:

Controller board: the analysis is provided here.

Edge detection system: the analysis is provided here.

Concrete mixing systems: the analysis is provided here.

Focused Feasibility: Prototyping, Analysis, Simulation

After determining the categories of components to be used by our design, a feasibility analysis was performed for each category.

Interface

We will be using a computer software such as RepRap Firmware as our interface. Most RIT engineering students have knowledge of how to use 3D CAD software. From the software, CAD files are converted to an STL file format. After selecting a layer depth, the printing path for each layer is generated to create a G Code file for printing. Proof can be found in Mix Design and Fresh Properties for High-Performance Printing Concrete or in Lund University 3D concrete Mobile Print.

Model of how user will interface with printer.

Mixer

The printer will not have an integrated mixer; the material fed to the printer will be pre-mixed, according to a procedure to be developed later in the project timeline.

Controller

Feasibility for the controller was fairly simple. We needed a controller board that would be able to handle many stepper motors and that can easily interface with 3D printing software. Arduinos have a library for translating g-code files to physical movement which can be found here. However, the Arduino lacks a lot of the stepper motor driver features that are required for stepper motor functionality.

The company Duet3D provides reasonably priced microcontrollers that include stepper drivers as well as an open source software package. For these reasons, it was determined that a Duet3D microcontroller solution would be feasible for our 3D printer.

Extruder Force Generation

The chosen concept for the extruder force generation was the auger. The purpose of the auger is to create enough force for the mixture to go through the nozzle. This concept is relatively cheap, and has been proved to work. For proof, visit the Lund University 3D concrete Mobile Print.

Material Delivery System to Extruder

The concept selection for the material delivery system to extruder was the auger, the same component selected in the extruder force generation. These two concepts relate to each other as one makes use of the other to generate the delivery of the mix (concrete).

Nozzle Design

The selected nozzle will be a square nozzle shape. It has been proved to be the most stable shape for Concrete printing, as it has been documented with fewer accidents than circular shapes. Documentation for this study is found in, Development of 3D Concrete Printing, which is a thesis for the degree of Master of Science in Building Technology.

Nozzle Material

The chosen material for the nozzle will be metal. The nozzle must be able to resist pressure build-up and at the same time, be lightweight. Also, as we benchmarked, most products used this material as a source for nozzle design. Proof of this can be found in Lund University 3D Concrete mobile Print , or the article A study into the effect of different nozzle shapes and Fiber-Reinforcement in 3D Printed Mortar.

Structure Material

A feasibility analysis was performed on the structure material to be used. The calculations assume a design solution (8020 material), but it is a good starting point for estimating the load the machine will need to support.

Concept Selection

Criteria	Description	Engineering Requirements Addressed
Easy to Integrate	The ease with which the component can be incorporated into the printer design.	ER1, 4
Repairability	The ease with which a component can be repaired after it has been integrated into the system.	Implicit to Design
Manufacturability	The ease with which a component can be fabricated by our team.	Implicit to Design
Budget	Will this component cost a disproportionate amount of money?	ER 21, 22
Lightweight Components	Low weight components will reduce wear and tear on motors.	ER15, 16, 17, 18
Flexibility	The versatility of components and ability for components to interface together.	ER13, 14
Rapid R&D	Product allows for fast setup and use.	ER3
Durability	How long will the component last?	ER2, 3, 7, 8, 12
Prevalence	How supported is this solution? Will the development team be able to find support using forums or manuals?	ER19
Safe	Does this component cause risk to other components or the user?	ER19, 20, 24, 25, 26, 27
Easy to Program	How easy is this component to integrate in software?	ER13, 14
User Accessibility	How easy is this component for the end user to use?	ER5, 10
Simplicity	Is the component more simple or more complicated?	Implicit to Design

Pugh Charts

For each category from the Morphological Chart, a Pugh chart was created. Pugh charts were used to decide which concepts to pursue in each category. Below, the chosen concept for each category is held as a datum while the remaining concepts are compared. A PDF version of the entire Pugh chart is also included in a link.

Interface

The interface is how the user will interact with the 3D printer. Primary decision factors for the interface were price, ease of executing a print file, and interfaces of 3D printers. Entire Interface Pugh Chart