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 MaterialsBased 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 DecompositionThe 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.
Systems ArchitectureTo represent the system architecture of the 3D printer, block diagrams were used. Three separate block diagrams were created with three different levels of detail.
BenchmarkingIn 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.
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.
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.
General Feasibility: Prototyping, Analysis, SimulationThese 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.
InterfaceWe 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.
MixerThe 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.
ControllerFeasibility 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 GenerationThe 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 ExtruderThe 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 DesignThe 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 MaterialThe 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 MaterialA 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.
|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 ChartsFor 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.
InterfaceThe 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
MixerFrom the Pugh chart results, a mixer was decided to be an unnecessary component of the printer. However, the way in which the concrete is mixed was still considered. The mixing process comes down to what is available to the user. Rotating concrete drums are the construction industry standard way that concrete is mixed, but hand mixing is viable for smaller batches. Entire Mixer Pugh Chart
ControllerThere are many potential micro-controller options for 3D printing applications. Essentially, the micro-controller has to move 3-6 stepper motors. An Arduino is suitable for this purpose, however there are controllers specific to large scale 3D printing such as the Duet 2. Entire Controller Pugh Chart
Extruder Force GenerationThe way in which the concrete is extruded determines the uniformity of the extrusion. A system for generating constant pressure while also being easy to clean and mechanically simple was chosen. Entire Extruder Force Generation Pugh Chart
Material Delivery System to ExtruderThe material needs to be delivered to the extrusion head. Other teams have relied upon simple gravity from a hopper to feed concrete to their print head, but the concrete mixture was too thick and did feed the mixture in a smooth constant manner. For this reason, a mechanical solution is being explored to augment the hopper system. Entire Material Delivery System to Extruder Pugh Chart
Nozzle DesignThe nozzle shape determines the characteristics of the extruded material. A square shape has been proven to clog less and create a more uniform shape. Entire Nozzle Design Pugh Chart
Nozzle MaterialThe nozzle material determines the durability and robustness of the nozzle. Entire Nozzle Material Pugh Chart
Structure MaterialThe structure material impacts how modifiable the machine is and the rigidity of the structure. Entire Structure Material Pugh Chart
Final Concept Selection and Morphological ChartThe final concept selection is detailed in the updated morphological chart. A concept highlighted in green is the primary concept, yellow is the secondary concept, and red is the tertiary concept.
Risk AssessmentThe Risk Management document for this phase can be found here. A preview png can be found below. For the final Risk Management and Progress document, see this link.
Preliminary Test PlanA test plan was designed for several critical Engineering Requirements and prototypes. The latest documents are found below.
Plans for Next PhaseAs a team, we would like to have selected exact components for the detailed design review. The Gantt chart below shows a plan of tasks that need to be completed during the next phase and the tentative schedule for each task. For the final Schedule Management document, see this link.
The three week plans for the system level design review
are found below.