The first case study was one of the earliest applications for the author in terms of simulation. One of the customers came with a RFQ for a group of parts for a compete assembly, mostly with HPDC except one part. This part is called "Cross Link" (Figure 1.1) and acts as a hinge between two moving members. The mechanical strength of this part was paramount.
Figure 1.1 - Original part - Cross Link
But customer wanted this part in GDC, which was to be outsourced and also expensive for its tiny size. Deeper discussion with the customer revealed that this part was originally a HPDC part, but was converted into a GDC after a field failure. Mechanical failure through breakage was the reason, and the customer was paranoid about reverting back to HPDC, though they were keen about it.
Hence a static analysis was taken up with the consent from the customer and the failure area was identified by duly marking the fixed areas and the loading points (Figure 1.2).
Figure 1.2 - Results showing the Fixed Areas, Load Points and Failure Area.
The simulation results showed a Factor of Safety of only 1.10 (Figure 1.3) at the failure area and there by exactly correlating the failure as described by the customer.
Figure 1.3 - Results showing the Failure Area with value of Factor of Safety as 1.10.
The assembly functions and fouling conditions were analyzed and it was decided to increase the width of the part (Figure 1.4) at the failure area there by improving the factor of safety and mitigating the failure.
Figure 1.4 - Modified Design with increased width.
The simulation results showed a Factor of Safety increasing almost twice to a value of 2.13 (Figure 1.5) there by giving a great relief to the engineering team and a conviction to go ahead.
Figure 1.5 - Results of Modified Design showing value of Factor of Safety as 2.13.
Since material was added to achieve the result the team was reluctant to be satisfied with the present outcome.
Improvement is a never ending process and a modified design with a weight reduction pocket was identified after several iterations (Figure 1.6). This has pushed up the Factor of Safety to as high as 2.45 (Figure 1.7).
The results were communicated to the customer in terms of reports with values, pictures and animations, and the satisfied customer readily agreed to revert hack to HPDC with the improved design.
Table 1.1 - Comparative Values of Factor of Safety far Original, Modified and Improved Designs.
Figure 1.6 - Improved Design with weight reduction pocket.
Figure 1. 7 - Results of Improved Design showing value of Factor of Safety as 2.45.
The highlight of this case was adhering to the customer deadline of just 24 hours, achieved while the customer was in transit from India to Germany after the final discussions. This was in 2003 and not a single failure has been reported so far.
Though the author had this tool for a few years and had a reasonable exposure as well, it was not used until this case arose. In the end it was found that "necessity is the mother of all inventions." This triggered the team not only to use more and more of this tool but to also seriously explore various other tools that come up in the field from time to time and use them earnestly and confidently.
To prove this point, please read on about the rest of the case studies.