Discussion board
nkg-iv
discussionboard2.docxHW6
a) Develop a set of operational requirements for a simple lawn tractor. Limit yourself to no more than 15 operational requirements
1. The tractor should be designed to not make an annoying noise.
2. The tractor should have a cargo with a good capacity of space.
3. The tractor’s inner parts should be designed to be accessible whenever maintenance is needed.
4. The tractor's frame body should be designed in a way that can carry two passengers with a very reasonable weight.
5. The tractor should be sensible for any uneven or unharvested areas.
6. The tractor should be built by materials that can last longer and weightless.
7. The tractor should be fuel economy.
b) Develop a set of performance requirements for the same lawn tractor. Limit yourself to no more than 30 performance requirements.
1. Covering the operation engine with a soundproof layer is capable of reducing the noise.
2. Building the tractor by materials that have high flexibility with a good range of resistance, can make the tractor’s weight reasonable and add strength to the body frame.
3. The blades should make 3,500-5000 revolutions per minute.
4. The tractor is electrical powered which make less noise compared to gasoline-powered tractors.
5. Adding reel blades which consist from 3 to 7 helical blades can make the shear cutting more efficient.
6. Helical blades reduce the chances of having uneven areas.
7. The tractor has a safety belt which can be pulled in emergency cases, making the blade operator shut off immediately.
8. The tractor can top speed of 20 miles/hr.
9. Steering wheel should help the owner to navigate the uneven areas.
10. A lighting system that allows the owner to mow the lawn at dark times.
c) How would you go about validating the requirements in (b)?
This is how I validate some of the performance requirements The blades of the lawn tractor revolve at about 3500 to 5000 rpm because its primary function is to remove unwanted grass and other small plants for leveling the lawn by the impact of the blade against the grass. For doing so it needs to overcome the shear force which is required to cut the grass etc using the rotary action of the blade only.
Adding reel blades which consist from 3 to 7 helical blades can make the shear cutting more efficient because as these blades rotates it creates a scissor-like cutting motion against the bed knife (a mechanism of reel mower) by forcing the grass between the blade and bed knife which reduces cutting force as compared to rotary type land mover where only the rotary action of the blade is used to cut the grass.
Helical blades feature slightly curved edges which help generate a continuous air flow as the blade rotates (like a fan). Thus creating a sucking and tearing action on the grass. Hence, helical blades reduce the chance of having uneven areas.
The tractor has a safety belt which can be pulled in emergency cases, making the blade operator shut off immediately to prevent any accident occurring during the operation of the tractor.
