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10

Summary: The design of genuinely waterproof containers is an arcane art but is reasonably doable if certain rules are adhered to which codify the underlying "magic". Failures occur when the basic sealing rule discussed below is violated. I.e. pressure on all sealing surfaces exceeds differential pressure at all times. In many products the failure is ...


10

How To Read the Graphs The graphs are plots of stress versus position. Stress is the force per unit area exerted on a material. Positive values are tension and negative values are compression. The first (leftmost) plot shows the normal stress vs. position that would be expected from bending if there was no pre-stress. The middle plot shows the pre-...


9

Stating categorically that bamboo is stronger than steel is a bit like stating that automobiles are faster than planes. On its face, it is a bit shocking, and seems wrong. But a rocket-powered automobile is certainly going to be faster than a one-seat propeller plane over a short distance on a controlled track. Then again, the same rocket car is going to ...


8

Pressure treatment does have a small, but documented effect on the strength of the member, particularly if it is 'incised' (has slots or holes cut into it as part of the pressure treating process.) If you're working to American codes, according to the American Wood Council, pressure treated wood is limited to a maximum duration factor of 1.6. This wouldn't ...


7

Assumptions The angle between the wall and the strut is $\theta$ $a$ is the depth of the table top $P$ is the weight on the table top, applied at the edge furthest from the wall The strut will fail when it buckles, which implies $F_{\text{max}}=\frac{\pi^2EI}{L^2}$ where $L$, $E$ and $I$ are the length, the elastic modulus, and the moment of area, ...


6

Using a tie-and-strut model makes it easier to explain the difference here. A tie-and-strut model is a simplification of the structure which describes where the structure is under tension, and where it is under compression. The model gets effectively simplified into a truss. Below we have two examples of the axial load on members of two different trusses ...


6

For impact: $$ \sigma_{max} = \frac{v}{V}E(1+\sqrt{\mu + \frac{2}{3}}) $$ Where: $V = \sqrt\frac{gE}{\delta}$ $g$ is Gravitational constant $E$ is Young's modulus $\delta$ is the weight per unit volume $\mu $ is the ratio of ball mass to bar mass $v$ is velocity of impacting ball Per Roark's Formula's for stresses and strains 7th edition, this can ...


5

The major factors surrounding failure points of waterproofing are, as has been said, the ingress of water around the main case opening and any I/O areas. For the main case opening, this ingress is usually mitigated by an O-ring. Due to the deformation of the O-ring under pressure, hard, 90$^\circ$ bends usually are the primary point of failure. This is the ...


4

Bamboo in its natural shape is very prone to splitting. Having any kind of hole will reduce its high bending strength resistance significantly. In addition, bamboo culm does not have a constant cross-section in the longitudinal direction, makes it harder to create a reliable bond. J.F. Correal "Bamboo design and construction" has few suggestions for bamboo ...


3

We really want to avoid putting wood members into torsional stress states. The previous answers are valid and applicable mostly for isotropic materials. Wood is an-isotropic and its material properties are the result of the complex structures naturally formed in wood. Trying to rely on planks in torsion is particularly problematic because the wood is very ...


3

The use in gyms and dance studios is not a good reference. Those floors are designed for dynamic impact loads from people dropping gym equipment and dancers jumping around. They need to be able to absorb the impact energy by deflecting under load, and therefore the plywood is introduced as a "soft" element which is able to bend with relative ease so the ...


3

Reading the paper, plastic buckling in this context means the collapse of micro-scale cells forming the structure of the wood, causing local buckling of the cell walls. The net effect of this is a global failure which presumably looks like a crushed band in the sample. In a sense, each individual cell wall is undergoing a constrained version of elastic ...


3

I assume that you are talking about a steel frame with a wooden body mounted on it. In general round tube is more efficient, but if the loading is primarily bending in one direction rectangular section can be better. So for something like a space frame chassis or roll cage where the whole structure can be subject to quite complex loading round tube is ...


2

For a waterproof container to be useful, you have to be able to open it and put something inside. The most likely location for failure is obviously at the points where the case opens up. This is usually dealt with by using a rubber gasket which compresses slightly when the case is closed, creating a continuous seal between the two sides. The most likely ...


2

Wood isn't a particularly waterproof material (it absorbs water & humidity), I would go for plastic or metal. To ensure the "waterproofness" of the case, I would suggest using an o-ring or similar foam gasket under compression, this is the best way to ensure it is sealed. Normally with o-rings, you would aim for a 20% compression. Now, there is the ...


2

So there's a permutation of rotation and translation each being either fixed or free for a column. What do each mean? To say that a specific degree of freedom of a support is "fixed" is to say that the support cannot translate along, or rotate about, that axis. For example, if it is stated that the translation of a beam is fixed in the X axis at one end, ...


2

A glass or tile drill has a cutting edge designed for that hard material which comes off as a dust. A wood bit cuts more material faster so it has a fluting designed to remove that material. Purchase and use the correct one for the job otherwise they can overheat and fail needing replacement.


2

Based on your nicely constructed model, it appears that two axes of movement will be required. The vertical axis can be addressed by a pair of bearing assemblies securely mounted to the top and bottom of the center pole: It may be necessary to find a different type of assembly which allows you to secure the inner race to the pole, but the image serves the ...


1

I wouldn't be that much worried about the support bracket. There are standard brackets that would more or less be able to handle the load. What i'd be more worried is that on the strong axis of beam there are 2700lb of load (vertical), while on the weak axis the applied load by my calculation is 11250lb. Assuming x is the horizontal axis (6 in), y is the ...


1

The floorboards functions are supporting and distributing loads on beams. Another function is to brace the beams. In the design of the beams we only consider the rectangle section beam, not I section. As you described in the question, the floorboards are nailed to the beam. Thus, if you cut the section of the beam, the connection between the boards and the ...


1

What you are looking for is already available as 70" TV mount, pull down over fireplace, in many Internet shopping sites for prices ranging between $50-100. I add a photo just as an example.


1

I would put plates at the corners, bolted where I've indicated (or choose your own spots -- just make it adequate, and think about how the wood is going to "want" to split when pressure is applied). You should be able to use 1/8" thick plain steel, and bolt them on with the same-sized bolts as are on your current brackets. I would leave the current ones ...


1

If you estimate force needed to straighten the door applied at the corner is 20kg, it would be equivalent to the reaction of a uniformly loaded beam (your square bar) at one end. So lets design the bar and for simplicity only the top bar, we can do the side later if we need to. Lets say the door stays out of door jamb 2cm at the corner. So now we have all ...


1

I don't think there is any problem with the idea, with these considerations. Heat register should be relocated to somwhere that is not likely going to be exposing someone to excessive heat or burn. 2x4 at 16" o.c. type 5 nailing is ok with with 16 d nails, unless you have decking screws with data sheet so you can adequately provide for 100 lbs/ sqr foot of ...


1

The results will be scalable, but you will be assuming the quality of the wood to be uniform throughout. In the Building trade there are standards that specify the size, number and location of defects such as knots etc - these reduce the carrying capacities etc. You need to either make sure the wood has no or few defects or oversize the material to cover ...


1

From a structural viewpoint, please let me enumerate the pros and cons of this idea - pipe vs rectangular hollow steel section (HSS). In terms of strength, circular profiles have the strongest moment of inertia (the one that resists bending) among structural profiles. Ex. For an HSS of 2'x3'x1.0mm THK, the moment of inertia is $201,744.50 \ mm^4$. For ...


1

The load that exert an human supported on two rods depends chiefly on: The weight of the human. How apart from the rods he is (measured in the horitzontal direction). How close are the two rods that support him. From the photographs you posted, those exerting a smaller load are those in which the person just hangs vertically from one or several bars. The ...


1

You could use polycarbonate tubing, it is used for safety glasses and other unbreakable items and is lightweight. It is not stress crack resistant though so if you need to drill holes in in it there will be micro-cracks where you drill the hole. It is then advisable to anneal the plastic if you want the finished product to last in an outdoor environment.


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