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FACET 6: Engineering Modeling and Analysis

Engineering Model

Developing an engineering model is when you can actually put your ideas to the test. An objective of engineering model development is to learn how to plan a test program for your engineering model. We will use the following steps for the engineering model:

Step 1: Build the model generated during the preliminary design phase. The model may be a software computer simulation, such as a finite element model, or it can be a scale model, or a full scale prototype. In addition to building the model, we need to prepare a test plan, and sequence of operations, along with a series of questions to be investigated.

Step 2: Perform the testing indicated in the test plan. Be sure to recall all original data in your logbooks, and document all experiments and interpretation of the experimental data as well.

Step 3: Prepare a report of your findings, along with an interpretation of your results.

Step 4: Use the findings from your experiments and your report findings to make improvements to your design.

Analysis and Synthesis

During an engineering design, you will undoubtedly encounter a number of problems need to be resolved. Attacking each problem in a methodical fashion will allow you to be more productive individually, and to communicate the results of your analysis more readily to the other members of your design team. You will commonly iterate between synthesis and analysis during your design. The engineering problem solving method presented here is a reasonable template for solving problems ranging from a classwork-problem to a large-scale analysis in support of an industrial design.

Stage 1. Problem Statement

Before solving a problem, you must state clearly and concisely the problem that you have been tasked to solve. Think of the problem statement as if you were writing your own homework assignment.

Stage 2. Summarize Known Information

During this stage of the analysis, you gather historical information, and relevant facts pertinent to your design. Sometimes, the known information comes directly from the problem statement. More commonly, the known information is taken from reference materials, supplier data sheet, material property database, and things of that nature.

Stage 3. Summarize Desired Information

Unlike the problem statement, which sets forward a strategic goal, the list of desired information consists of a series of tactical tasks that must be accomplished in order to achieve the full solution.

Stage 4. Assumptions

We need to list the basic assumptions and constraints under which our analysis will proceed. For example, if we make the assumption of one dimensional heat transfer, we would list that assumption at this point in the design document, and identify whether it is a conservative or a non-conservative assumption. Further, we need to support the validity of our assumptions, or note that the validity remains to be determined.

Stage 5. Schematic and Given Data

In this stage, we gather drawings, sketches, and numerical data to support our design. This is where we deal with instrumentation issue, gathering property information, and things of that nature. This step becomes rather voluminous. You may gather the data in a spreadsheet format.

Stage 6. Analysis

This is the stage where we get into the essence of the problem. If you developed a mathematical model for your problem, you recall the governing equations of physics that apply to the problem. Then you substitute the known information, apply the simplifying assumptions, and solve for the unknowns.

Stage 7. Review results

Before we make any judgments about a design, we must convince ourselves that the analysis performed was reasonable and accurate. After you have completed an analysis, have an independent member of your design team check your problem statement, known information, desired data, your sketches, your assumptions and their justification, and your solution. Stand back together and confirm whether your answers appear reasonable and have the proper units.

Stage 8. Synthesis

Use the findings from your analysis to revise the underlying design of your product, device, or system. Many times, the solution you develop form the analysis will require you to revise your drawings. Sometime, you can fundamentally simplify the design concept based on your findings. On other occasions, your detailed analysis findings may lead you to the conclusion that you need to rethink your design at a more basic level.