Simple Design Project: 'Walnut Cracker'

[aznkid310]

Here's what I need to do:
Walnuts are an important cash crop in Yolo County and are popular to consume around the holidays. To give the market a boost, it would be useful to have a device which would facilitate walnut cracking and also be fun to use. Recognizing this need, the objective of this design project is to design an impact walnut cracker which meets the following design criteria:

1. The device must operate in the horizontal position.

2. Impact must be provided by a mass sliding on a track which is accelerated by a linear spring(s).

3. The mass must strike a ‘firing pin’ which slides in a bushing and applies the impact load to the walnut.

4. The nut must be temporarily encased during impact to prevent the nut shell fragments from scattering.

5. The device must be designed to crack an infinite number of walnuts.

Some of the primary design considerations include the slider mass, the sliding distance, and the spring rate. Specifying these quantitatively depends on the energy required to crack a walnut shell. To determine this energy, you will need to devise a simple test to determine the average and standard deviation of the energy required to crack 10 nuts. This data will then be used for the design.

Your assignment is to conceive a device which meets the above criteria, perform the necessary calculations to select both material and geometry so that none of the structural components experiences fatigue failure, generate the working drawings to manufacture the design, and finally to communicate your design through the preparation of a design project report. The contents and format of the report are described in a separate handout.

To get started, I need to determine the energy needed with an experiment. Anyone have any ideas for how I should do this?

 

[Danger]

This seems to be a homework assignment. As such, it's in the wrong place.
I hate walnuts with a burning passion, but if I have to crack one for the wife I use a hammer.

 

[oswaler]

I would suggest conducting an experiment to determine the energy required to crack a walnut shell. This can be done by using a device that applies a controlled amount of force to the walnut shell until it cracks. The force needed to crack the shell can then be measured, and this data can be used to determine the energy required.

One possible setup for this experiment could involve using a force gauge or dynamometer to measure the force applied to the walnut, and a device such as a vise or clamp to apply the force. The walnut can be placed in the vise or clamp and the force can be gradually increased until the shell cracks. This process can be repeated multiple times to get an average and standard deviation of the force required.

Another approach could involve using a dropping weight or pendulum to apply a known amount of force to the walnut shell. The height of the drop or swing of the pendulum can be adjusted to vary the force applied, and the height at which the shell cracks can be measured to determine the force needed.

Once the energy required to crack a walnut shell has been determined, it can be used to inform the design of the impact walnut cracker. The mass, sliding distance, and spring rate of the device can be calculated based on this energy, and appropriate materials and geometry can be selected to ensure that the structural components do not experience fatigue failure.

In addition to the design considerations mentioned, I would also suggest considering the ergonomics and safety of the device. It is important to ensure that the device is user-friendly and does not pose any safety hazards. This could involve incorporating features such as a non-slip base, a protective casing for the firing pin, and easy-to-grip handles.

Overall, this is an interesting and practical design project that has the potential to benefit the walnut industry in Yolo County. I look forward to seeing the results of your experiment and the final design of the impact walnut cracker.