9

You are worrying about the numbers and forgetting what the numbers mean. This is for the PE exam, so this is a very important topic to make clear in your mind. You solved the problem. You came up with an answer for what is required. You now have two options: Choose a small footing that your own solution just proved is too small for the requirements. Choose ...


7

As your construction is 3D printed, increasing the strength at the point of current breaking will more likely transfer the damage to a new location. The obvious and possibly impractical solution is to solve the jamming problem, rather than to try to power through it. If it's not practical to prevent the jamming, consider to convert the jamming related ...


5

You might consider dealing with it in software. Sense the stepper motor current, and when it exceeds a certain threshold that indicates jamming, perform a high speed reverse rotation for one or more revolutions. Then proceed in the forward direction.


5

Build the auger around a stronger shaft which has a better connection to the motor shaft. Perhaps a carbon fibre or even a steel centre. But then consider what will be the next breaking point. Or make a joint between the auger and the motor that fails if the mechanism gets jammed - just make it easy to replace.


4

For me a good (compromise of a) solution would be to redesign the shaft with an rectangular slot (although I am still unclear as to the fracture type, so I suspect is torsional). Like so Then you can use a rectangularly shaped metallic shaft along the length, which will be able to transmit more gradually the torque. *Figure 2: rectangular shaft image ...


3

On top of flexural deflection, the Timoshenko Beam Theory includes a term called "Shear Deformation" that is to account for the additional deflection and shear stress due to shear effect, which is quite samall compared to the effect from the flexural, thus it is usually ignored except higher accuracy is desired. (See figure below) The slope of the ...


3

In machine tools where an auger is used to remove scrap metal chips, the current in the auger motor is sensed. If it exceeds a certain level due to jamming, the electronics temporarily reverses the auger direction which can clear the jam. Lubrication of the material-auger interface is very important with augers, which have a huge swept surface area.


2

If you know the torque, or a close approximation of it, you can size the auger shaft more appropriately. From Machinery's Handbook the max torque T a shaft can handle is T= S_S* Z_P S_S = allowable torsional shear stress of material Z_P = polar section modulus (0.196 * diameter^3) Make sure your units are consistent. So you can either use a stronger ...


2

Usually $\kappa = \dfrac{\text{average shear strain on section}}{\text{shear strain at centroid}}$ but the problem with this definition is that it depends on external loading so you can't actually make a table for $\kappa$ values. However, we could make an assumption and define $\kappa$ purely in terms of the shape of the section: $\kappa_i = \frac{1}{\...


2

This isn't a real answer, but I feel compelled to provide it. What you are suggesting is perhaps possible, but very, very complicated. You will need to hire experts to engineer a magnetic bearing of this size and it will be extremely expensive. I'm confident you will not be able to engineer this with a series of questions on Engineering Stack Exchange. There ...


2

It won't help prevent swinging, and in all likelihood would keep the door swinging longer after an impulse force is applied. As the comments suggest, most inside doors have a guide on the floor (usually in the retracted region, not the doorframe itself). If you have a barn-door-type sliding door, there may well be a guide/stabilizer near the top of the door.


1

Because the weight is quite high, and the use is for supports, I will assume that you will use the same cross-section for the shelve columns (if there are any). In you use the same cross-section, you probably will not have a problem with buckling I am assuming RHS refers to Rectangular Hollow Cross-section. Regarding the process that you need to follow IMHO ...


1

First of all, the two methods you suggested (buying pad materials and spring+damper) are not necessarily different. Usually the different pad materials that can be bought, (mainly) modify the spring constant in the structure. Additionally, although there are methods of targeting specific frequencies, in most cases they are not very useful. The reason, is ...


1

It is called a "fuse" connection, sometimes called the "fuse block", "fuse plug" depending on the trade. Essentially it is simply a weakened link/connection between two components or a necking area in a location within an element, which is often seen in the tension test, so the failure can be triggered and limited to the ...


1

You are missing seepage with humidity. Seepage is the infiltration of water into the living space (basement) and makes the space wet or moist. It does cause concern about humidity, but seepage alone won't cause the humidity to reach the extent that is uncomfortable (for humans) and harmful for building materials. It needs to work with the elevated ...


1

NFPA 13 is the industry standard on all matters related with sprinkler systems in the USA. However, as a standard, it needs to be adopted by each of the States Building Department to incorporate into the State Building Code. Also, the State may impose additional requirements, as Amendments to NFPA 13, which are also to be met. So, in your case, you shall ...


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