27

There are two reasons why. First, for any glue to stick to something, that something needs to be wettable by the glue. A cured silicone surface is bristling with uncrosslinked silicone units which have extremely low surface energy and hence are very difficult if not impossible to wet by glues like epoxy. This means the cured epoxy exhibits no adhesion to the ...


24

The photo you have is not for the standard jigsaw blade. Standard blades teeth point upward and cut upward for the obvious reasons: less wobble, more control, center of force near the handle. This is a revers cut blade designed to cut on downstroke to cut laminated work like countertops, so that the cut is not going to splinter the Formica or other laminate ...


16

If you think what happens as each tooth cuts material then the blade is put into tension as it cuts, this means that the blade is likely to stay straight, but any unevenness between the teeth side to side may cause drift. If the blade cuts on the downstroke it will buckle as it is relatively thin for its length. A blade designed to cut on the downstroke ...


11

To enlarge slightly upon Solar Mike's response, a jigsaw that cuts on the upstroke tends to yank the saw shoe down into firm contact with the workpiece. This guarantees that the cut angle will match the shoe angle; for a shoe angle of 90 degrees this means a nice square cut.


11

One of the mechanism that affect corrosion is known in the literature as Stress Corrosion Cracking (SCC). The idea is that tensile stressed regions are prone to crack development. Crack development essentially maximizes the area that corrosion can develop. Since corrosion, degrades the properties of the material, this accelerates further the crack ...


9

Silicone is not a single substance, it is a very very wide range of different types of materials with widely varying properties! All materials that have several siloxane monomers in them can reasonably be called silicones. This can take almost any shape; foams, glues, coatings, rubbers, oils, powders, gels. 3D printed solids, even. Some silicones will adhere ...


7

Let me see if I understood it correctly: You have a rubber block under a uniaxial load (compression or tension). That block may or may not be constrained on one pair of sides (the load is applied along the block's x-axis and the block can't deform in the y-axis but can in the z-axis, for example). If this is the case, then the 1.33 is easy enough to explain. ...


5

Solar Mike's answer is accurate. Carbon fiber has a resin to fiber ratio which provides the optimum strength. This is typically measured by weight. The amount of resin is applied to the fiber prior to enclosing it for vacuum application. Once the vacuum begins, all of the air is removed from the fiber, forcing the resin into the voids, ensuring the ...


5

To expand on Solar Mike's answer and to help explain part of niels nielsen's answer, the saw blade is normally designed to essentially squeeze the material between the teeth and the shoe. This generally makes for a more controlled cut. Circular saws, saws-alls, and most other mechanical saws work on this principle, too. If you were to use the blade you have ...


5

Material Properties For the linear-elastic analysis you describe, the key pieces of material information are the elastic modulus (E) to calculate deflection and the yield stress (Fy) to check if the material remains elastic under the given loading. For steel, E is commonly around 200 GPa. The Fy can vary significantly depending on the grade of steel, so you'...


4

Steels are usually considered "as cast" or wrought. The microphotograph is overetched and either high magnification or coarse grained , likely had a heat-treatment. Cast or wrought would be identified by inclusion morphology , best seen in unetched condition. Modern steels are very clean so minimum inclusions to look for. Modern steels are also ...


4

I don't think of a screen protector as a mono layer, but a lamination. Deformable (softer) materials (possibly above and also) below the rigid layer (this layer also generally provides adhesion). That way point loads become distributed (potentially to the protector and also) to the device. Example: a thin clear sticky low molecular weight polymer (1), an ...


4

In the real world ,I don't believe I have seen CORROSION at STRESSED areas. Corrosion may be accelerated at STRAINED areas; the strains introduce energy to the microstructure which may promote corrosion. Cracking is another story - which you did not ask about . Hydrogen cracking of high strength steels is likely the most common case . It can often occur with ...


4

You left off a "T" ; it is "time, temperature, transformation". It is a basis to evaluate hardenability of alloy steels. A sample is austenitized, then rapidly cooled to some temperature ,and held at that temperature for a specific time . Then rapidly cooled to room temperature and the microstructure examined . And after one finishes the ...


3

In this case, we say that $\epsilon_{axial}$ ($z$-direction in your diagram) is positive by convention. Then, for a normal material with a Poisson's ratio $\nu \ge 0$, $\epsilon_{transverse}$ ($x$- and $y$-directions in your diagram) will be negative. The fact that the material is isotropic means we have no way of distinctly labeling one direction $x$ and ...


3

cell phone housings and trim, Lego blocks and all other similar types of plastic toys, camera housings, plates, bowls, and dishes of plastic as well as plastic knives, forks and spoons, automobile dashboards, PC and tablet housings, refrigerator drawers, plumbing pipe, fittings, fixtures and sinks, electrical enclosures and conduit fitments, booster seats ...


3

Strain is determined as $\epsilon = (l - l_o)/l_o$. The 0.2% offset strain is the point where $\epsilon = 0.002$. The 0.2% offset stress is determined by using a line that has the same slope as the initial stress strain ... the initial Young's modulus. In materials that are fully elastic up to and beyond this point, the initial slope remains constant. In ...


3

CTE characterizes dimensional change, with no load. It corresponds to a relatively fundamental physical principle, making it easy to use in a design calculation Heat Deflection test characterizes the deformation under heat AND load, which includes a variety of phenomena happening at the same time. The result is dependent on the particular geometry and ...


3

Usually the method to measure the toughness is either the Charpy or Izod Test. They are very similar and the main difference are the boundary condition of each one (Charpy fixed both ends, Izod: vertical cantilever). The setup is the following (and the differences) are presented below. Figure : Charpy and Izod impact testing (source Green-mechanic) As you ...


2

There are two reasons: One is to remove trapped air bubbles and two to pack the fibres as densely as possible within the structure or weave of the fibre pattern wanted.


2

I confirm that in your case the yield stress is an adapted limit value. However, there is a unit error in your computation. You forgot to convert the area in m2 which means that the results is not 362 Pa but 362x106 Pa = 362 MPa. Assuming that your reasoning is correct to compute the effort, your are above the limit of 170 MPa.


2

A rupturing pressure vessel consists of an interplay between rupture of the walls, that causes a reduction in pressure via venting, while rupture of the walls also weakens the ability of the structure to sustain more pressure. Which one declines faster, and to what extent, determines what happens next. If the rupture on the wall is small and does not ...


2

Although the deflections equation @kamran reported, are indeed what most textbooks give, the problem is that they only hold true for relatively small deflections. I also agreewith @alephzero that there are a few errors in the calculations. e.g. I calculate $Ix = 0.0491 cm^4$. By my calculations, you would need a steel rod with almost 11cm diameter to support ...


2

Machinability index is measure for cutting processes which shows how easy it is to remove material. It is used by comparing the cutting speed to a reference value for steel. I.e.: you try to find what is the speed that a cutting tool will last 20 minutes while cutting a given material. $V_m$ you compare $V_m$ with the reference speed $V_r$ (which uses steel ...


2

Here is a detailed list for metals both ferrous like steel and cast iron and, nonferrous like copper and their alloys Machinability Rating Chart. machinabilty index


2

The data sheet says it has a 71ksi yield, I see no reason to doubt it. Cold drawn is likely stronger near the surface which would be an advantage for bending resistance. SAE 1045 means it means it is carbon steel with 0.45 %carbon. The primary feature or the material you list is a precision dimension surface . It will have low toughness but I can't imagine ...


2

Geick Technical Formulae has tables of common values, but that info is spread across several tables. One you missed is electrical resistance. The book also contains tables for density etc


2

that is a scanner that converts the writing on the board into a digital file for remote sharing, and then erases the board. These devices use either a rack-and-pinion gear arrangement with the rack running along the top edge of the board, or a flexible cable-and-pulley system with an electric motor coupled to the pulley through a set of reduction gears. You ...


2

Well mass and high-temperature behavior are really the key benefits with carbon/ceramic brakes. High temperature: Their high temperature properties make them more dependable during heavy use as they barely suffer from brake fade, they are also not prone to warping due to carbon fibers extremely low coefficient of thermal expansion (CTE). The CTE is actually ...


2

I'm not an expert, but the disk in a disk brake system needs to absorb enourmous amounts of heat to dissipate the energy of motion. It then needs to transfer that heat to the air. Polymers generally are poor heat conductors and have relatively low heat capacity. Add to this lower strength and you have a poor choice for disk material. As Jim Clark mentions in ...


Only top voted, non community-wiki answers of a minimum length are eligible