Nov 022018

FEA of critical components

Wheels and Castors

The chassis is supported by two back wheels, with a castor in the back. In this analysis, Alex will analyze the structural integrity of the wheels and castors under realistic loads, and determine critical loads. In doing this analysis, one must take into account the Von-Mises stresses so that we can evaluate whether the stresses incurred are close to the failure stress. For some materials, we do not know the failure stress, so we are going to compare the Von-Mises stress to the yield stress.  This analysis is done in ANSYS Workbench 19.1. First, we will perform the analysis on the wheels.

We are going to make an assumption that the wheels that we have 3D printed are made up of ABS plastic instead of PLA. This is because PLA is not available for analysis on the ANSYS platform. The geometry uploaded on ANSYS is from the above mentioned file CAD model. The forces act at the center, where the shaft resides.

Nov 012018

Bill of Materials

A bill of materials is a list of the raw materials, sub-assemblies, intermediate assemblies, sub-components, parts, and the quantities of each needed to manufacture a final product (En.wikipedia.org, 2018). The bill of materials for Team Breaking Wind’s prototype is shown below in Table 4.1. A bill of materials in professionalism is valuable because the engineer, who knows which parts an assembly needs, is not in charge of purchasing. The bill of materials is then passed on to the employee who is responsible for purchasing. It is important for the bill of materials to be complete, concise, clear, and accurate. Any error or lack of clarity could cause the purchaser, who is not familiar with the assembly, to make a mistake with ordering and delay production of the prototype.

A bill of materials is directly linked to the available assets list created in Assignment 3 (See Appendix A Available Assets). For the purposes of Assignment 4, any free student workspaces likely to be used and competencies of the team will also be included to ensure buildability of the design concepts. As junior engineers, we will be utilizing the bill of materials to ensure that all necessary components have been acquired, since we are responsible for acquiring our resources ourselves.

Oct 312018

CAD Model – Concept 2

Various views of our second concept Alternator can be found below in Figures 1-5. Figure 1 shows the top view of the vehicle, and the large, flat surface for carrying payload. In Figure 2 the undercarriage of the vehicle is shown. This is where all the machinery will go to create payload space. From these perspectives it is impossible to see the wheels, so an angled view is shown in Figure 3. Lastly, Figure 5 shows the hub assembly, the motor bracket which holds the motor in place, and the funnel attached to the fan. Like Concept 1, the funnel will end up looking somewhat different because it will be made of cardboard and taped to the fan.

Figure 1 Top View of Concept 2

Figure 2 Bottom View of Concept 2

Oct 292018

CAD Models – Concept 1

Generating CAD models for parts is incredibly useful for several reasons: namely assembly, FEA simulation, and data sharing. CAD modeling software allows you to create individual parts, and then assemble them to see how the components will fit together and even how parts will move around each other. It also allows for stress simulation for certain CAD modeling softwares such as Solidworks, which is what our team will be using. Further, Solidworks parts can be directly imported into FEA simulation software such as ANSYS to conduct fluid flow analyses and stress analyses of critical components. Lastly, CAD modeling software expedites the process of creating engineering drawings, allowing one to potentially create many drawings in one day. Engineering drawings are then used in production to establish the standards by which parts should be created.

Model 1: Sonar

Various views of our first concept Sonar can be found below in Figures 1-4. Figure 1 shows the top view of the vehicle, and the large, flat surface for carrying payload. In Figure 4.4 the undercarriage of the vehicle is shown. This is where all the machinery will go. From these perspectives it is impossible to see the wheels, so an angled view is shown in Figure 3. Lastly, Figure 4 shows the hub assembly, the motor bracket which holds the motor in place, and the funnel attached to the fan. For our prototype, the funnel will end up looking somewhat different because it will be made of cardboard and taped to the fan.

Figure 1 Top View of Concept 1 Figure 2 Bottom View of Concept 1
Oct 252018

Refined Concept Description

Since the concept descriptions generated in Assignment 2, more insight into the two primary design concepts has been obtained. In this section, the Go/No Go matrix was used to select the two concepts, and then to refine them (See Appendix B Go/No Go Matrix). The refined concept descriptions including new information are provided below.

Concept 1-Sonar:

Figure 1 below shows a conceptualization of Concept 1-Sonar before refining the concept. The current rendering of the robot can be located in the CAD Drawings section. Wind is collected through a turbine connected to a motor, which generates energy stored in a battery. The DC electric energy in the battery will be used to propel the device around the track with the assistance of two wheels and a castor wheel, as well as multiple motors to allow for turning. The device will be activated by a button and features an Arduino Uno for the brain, which we will program to use a sonar sensor to read data. For each component, the means by which it will be acquired is listed in Appendix C.

Oct 212018

Reduction of Concepts

After carefully analyzing the design concepts selected from the morphological charts for technical feasibility, functional feasibility, and buildability by using evaluation criteria and Go/No Go analysis, the six concepts have been reduced to two concepts. It is important to have two concepts, rather than just one, because one is the primary choice and one serves as a back-up design. In the event the primary choice is not feasible in some unforeseen way, having a back-up design on standby will allow our team to quickly jump into the next design concept, helping us to stay on track and meet deadlines.

Referencing the PMI lists for each design, which can be found in assignment 2, we were able to narrow our designs from six to two.

Oct 202018

Go/No Go Analysis

Below in Table 1 is Team Breaking Wind’s Go/No Go analysis of each of our six design concept systems. The evaluation criteria from the previous section make up the left-hand column, and the following columns detail whether the design system meets the requirement or not. If the requirement is met, the cell is highlighted green with the word “Go”, however if the system does not meet the requirement the cell is highlighted red with the words “No Go”. A Go/No Go matrix is a methodic procedure to determine which design concepts are likely to be the most effective solution to the problem statement based on the evaluation criteria, which of course includes buildability, technical feasibility, and functional feasibility. The Go/No Go analysis will also be used in Assignment 4 to write a refined concept description for the primary design concept.

Oct 182018

Evaluation criteria

List of Criteria

Evaluation criteria should be informed by the list of assets which is already in place. One key characteristic of the list of criteria is the requirement should be written so that the evaluation results in either “yes” or “no”. Criteria should include buildability, reliability, and maintainability in case anything goes awry. Design concepts should also be evaluated based on buildability, technical feasibility, and functional feasibility. At this point in the design process, our team can write informatively on the technical and functional feasibility, and we can speculate on the buildability of design concepts. Furthermore, the list of evaluation criteria should be developed from customer requirements and cover all aspects of the device. The table containing the criterion should also be divided by demands and wishes when appropriate. When constructing a list of evaluation criteria, it is helpful to look at the requirements list and make sure the evaluation criteria includes anything pertinent from the requirements list.

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