Bozo's queries

[Bozo]

Alright, so when i do structures and materials questions. I find myself basically taking an educated guess from the stress strain graphs whether a material is tough, strong, ductile etc.

Would anybody have a list or summary of what features a graph must have to suit a specific characteristic of a material?

Cheers  8-)

[Plan-B]

For a stress-strain graph:

Toughness is how much energy a material can absorb before fracture. Therefore if comparing materials, the material that possesses the largest area under it is the toughest. As the energy it can absorb is equal to the area under the graph multiplied by volume.

Brittleness: How much strain a material can withstand before fracture. They are considered brittle when they fracture shortly after reaching it's elastic limit. Therefore brittle materials generally have a linear line.

Ductility: How much plastic deformation before fracture. Materials are considered ductile if after it's elastic limit (linear region), it continues without fracture in non-linear ways for extensive values of strain. Sooo the line looks long

Stiffness: How much force it takes to change the shape of an object. This is the gradient of the line (a.k.a Young's Modulus). Soo the steeper the gradient, the stiffer the material is.

Strength: The amount of stress it can withstand before failure. Therefore a strong material in comparison would be the line that reaches the highest point on the graph.

Ehh, that's how i understand it

[Bozo]

Thanks man.

Another question. Has anyone here done a neap diagnostic test for electronics and photonics?

[Shark 774]

Thanks man.

Another question. Has anyone here done a neap diagnostic test for electronics and photonics?

No I haven't, do you have a copy of one?

[cranberry]

On a company exam i did, an answer was tensile strength = stress at elastic limit on stress-strain graph, not @ the max stress..

is this correct?

[Bozo]

.

[soopertaco]

On a company exam i did, an answer was tensile strength = stress at elastic limit on stress-strain graph, not @ the max stress...
is this correct?

I'm pretty sure tensile strength of a material should be equivalent to its 'ultimate strength' which refers to the max value of stress regardless of whether it is in the elastic region or plastic region unless of course the material fractured at the elastic limit??

[cranberry]

On a company exam i did, an answer was tensile strength = stress at elastic limit on stress-strain graph, not @ the max stress...
is this correct?

I'm pretty sure tensile strength of a material should be equivalent to its 'ultimate strength' which refers to the max value of stress regardless of whether it is in the elastic region or plastic region unless of course the material fractured at the elastic limit??

thats what i thought too....probs a mistake, but can anyone confirm?

[Bozo]

Ok, so i've come across this question in the 09 INSIGHT. The answers show the Vout graph non clipped but by looking at the characteristics of the vout vs vin graph. Shouldn't there be clipping?


What would this Vout wave look like?


Thanks!

[b^3]

Yeh the Vout graph should be clipped because the amplifer is biased at 2.5ish(mV) and not 0. It should clip for the values less than 0.75mV. So im guessing the suggested solutions are wrong then. Anyone else want to confirm?

[Bozo]

thats what i thought.

[b^3]

It makes sense, unless there is something tiny that we are missing.

[Bozo]

So its wrong 100% yeah?

if so what would it look like.

[b^3]

I'm 98% sure the question is wrong because they don't even give you the right scale to draw it on. Beacuse the amplifier is biased and inverted, the numbers say we should get this funny looking wave. It clips for values less than 0.75mV which coreesponds to 10V. The maximum which is the minimum for the output becaue its inverted is input = 1.5mV which means output = 8.5V. This question is really stuffed up. anyway hope this helps.

Edit: Sorry I forgot to shrink the image file down, so save the image if you cannot see it properly.

[Bozo]

Thats exactly what i drew. Cheers man.