Alessandro Rush
Product Design
Gimbal & Digital Analysis
For this project I had to create a Gimbal in SolidWorks, using different digital tests to see how the product would mould and how it would react to different stress scenarios.
CAD Model
The Gimbal is made out of 10 parts:
-Cap
-Body Front
-Body Back
-Pivot Part
-Armature 1
-Armature 2
-Holder Case
-Arm 1
-Arm 2
The Cap and main Body Parts have internal ribs to strengthen the structure of the product. These are the parts to be tested in the next section.
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Digital Testing
Digital testing was divided into 2 different sections. The first involved a Moldflow Analysis, using the Cap of the gimbal as the subject of the tests. The second was a stress test in which the model handle (all parts except the armature and grips) were tested as a whole. In this second part the tests were carried out twice, applying the same parameters to two different materials to determine which was the best (Pp & ABS).
Moldflow Analysis
The totally green model shows that the model will fill with ease with a single injection point. If there had been any problems the model would have changed to different colours indicating the most affected areas.
Ease of Fill
Air Gaps
The points represented show the places where air is trapped when the material has been injected.
Shrinkage
This image shows the different shrinking points. The model seems to shrink by 17.7% in the worst-case scenario, specifically at the two extremities of the part and in the middle by the injection point (red arrow).
Flow Speed
This image shows the first result to emerge when the Moldflow analysis is carried out, i.e. the flow speed. The analysis determines how long it would take to inject the material into the mould - in this case 1.19 seconds
Stress Testing
Acrylonitrile Butadiene Styrene (ABS)
-ABS (pp)
-25 kg pushing down onto the pivot point
-Product base is fixed
The image on the left shows the areas under the greatest amount of stress. The material should sustain this quite comfortably, since the yield strength of ABS starts at about 20MPa.
The right-hand image shows the displacement of the material
Polypropylene (PP)
-Polypropylene (pp)
-25 kg pushing down onto the pivot point
-Product base is fixed
This time the material is Polypropylene. Here too, no issues emerge in terms of the yield strength.
Both materials would benefit from extra support by adding ribs to the pivot area and the curved surface.
Torque Testing
Acrylonitrile Butadiene Styrene (ABS)
-ABS
-25 kg pushing sideways around the location of the Handle Cap onto the pivot point
-Product base is fixed
This time the the material yield strength is being tested much more as it enters the point where it starts to fail; moreover there is also significant displacement, which could potentially cause the product to separate from its other parts.
Polypropylene (PP)
-Polypropylene (pp)
-25 kg pushing sideways around the location of the Handle Cap on to the pivot point
-Product base is fixed
This image more clearly shows displacement of the handle; ABS seemed to do a better job at containing this aspect than PP. To combat this issue, ribs can be added to the product parts in both directions to offer extra thickness and greater rigidity at some points.
Drop Test
Acrylonitrile Butadiene Styrene (ABS)
-ABS
-2.5 Meter fall
-Impact product base
The point of impact was directly on a location akin to a corner, and with a force of 205 MPa this would certainly break the corner; apart from this the model emerges fairly well and seems to settle at around 20 MPa.
To fix the point I would adjust the model and apply a radius around the length of the base. The model did also distort downwards in the upper part by 3.82 mm.
