Weed whacker analysis
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• Weight = 1.080 lb<br /> | • Weight = 1.080 lb<br /> | ||
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r = distance from origin | r = distance from origin | ||
Revision as of 17:06, 8 November 2008
Contents |
Summary
Mass/Inertia Comparison
Gas
1) Elbow plate
• Weight = 1 lb
2) Upper shaft, torsion cable
• Weight = .963 lb
3) Handle, trigger
• Weight = .229 lb
4) Lower shaft, torsion cable
• Weight = 1.069 lb
5) Shield, weed whacker upper head, weed whacker lower head, spring, bearing, bump knob, wire
• Weight = 1.080 lb
m = point mass
r = distance from origin
Assumptions: Point masses Weed whacker is held at approximately a 45° angle
From our calculations, we found the inertia from the point of the elbow plate to be:
Inertia = 1719.66 lb in2
This mechanical analysis shows the significant change in both mass and inertia our new design has in relation to the original weed whacker. Specifically, the new design’s inertia is 64% of the original. This also means that the energy required to sweep the trimmer one foot is 64% of the original as well. The ease of use is a major concern in our design process, and these numbers show that our new model takes a big step in the right direction. These numbers are also important in considering the new way the trimmer will be held. Although the trimmer will now only be held with one hand, the majority of the weight will be held up by the straps around the forearm. The trimmer originally weighed 11 lbs. Now it weighs just over 4 lbs. The combination of weighing less than half the original weight and the additional support given by the forearm gives us confidence that the user will feel much less strain from our new design. The combination of the lower inertia and the forearm support shows how much easier it will be to use our product. The user will now have significantly more control when moving the trimmer from side to side. The old design required coordination between both hands, and its weight and inertia made it awkward and clumsy. The one-handed design allows the user to control the trimmer with the very simple movements of his arm. This improvement in ease of use allows the user to both trim more efficiently as well as more accurately.
