A highly cross-linked epoxy resin has a coefficient of linear thermal expansion α = 5×10−5 K−1, GIC = 120 J/m2, E = 3.2 GPa, and ν = 0.35. A thick layer of resin is cured and is firmly bonded to an aluminum part (α = 2.5 × 10−5 K−1) at 180◦C. Calculate the minimum defect size needed to initiate cracking in the resin on cooling to 20◦C. Take α in Eqn. 5 to be 2/π for penny-shaped cracks of radius a in a wide sheet.?
It is true that fracture toughness is a specific value of stress concentration factor,though K(Kc) is not stress intensity factor,it is fracture toughness. If the material is broken(a fracture occured) we say that Kt(Stress intensity/concentration factor)>=Kc.
Can anyone explain the difference between the two equations for Fracture toughness equations such that: K = (y.p)/(h.w^0.5) or K= Y. STRESS.((Pi.a) ^0.5)
i think there is no difference between in two equation. in first maybe you have a rectangular plate subjected to load P and have thickness, " h" & width ,"w" .. so stress = P/(h×w) , h×w = C/S area of rectangle you can put stress value in 2nd equation .. but , K= y×(p/(h×w))×sqrt(PI×a) .. i got this equation( maybe i am wrong) ... sorry for my english ..
Thanks for this great video! is Y determined by the second moment theory of a bending beam? i want to estimate the ideal thickness of borosilicate rod under Bending Stress, and to determine how the critical radius of a notch will change with the increasing of the rod radius. how can i simplify it by this theory? thanks in advance!
What are the formulae to determine stress intensity factor for all three modes for an edge crack on a turbine blade sujected to 3600 rpm rotation and temperature? Can anyone suggest relevant research articles. It will be really helpful.
Thanks for a clear explnation!. How do we arrive at the crize size ..a for calculation. Ex In FEA , I get some hot spots and I know the magnitude of vonMises stress. How can I calculate the fatigue for such cases?
how do you calculate the critical crack length?E and Gc are given as is the maximum working tensile stress that the plate needs to withstand which is 400MPa. E= 7.2 x 10^10 Pa Gc= 6300 Jm^-2
Alex Quinn In a similar as any dimensioning in mechanics. Write up the equation for when it's just about to fail, and that would be when your crack is so long that the stress you have is enough to to crack your material. So just copy the equation and call your crack length a_C. K = K_IC = Y*sig*sqrt(pi*a_C)
Is 'a' the initial crack length or the varying crack length. How does the testing machine determining the crack length calculates the crack length, when it plots dA / dN vs DeltaK curve?
Y is geometric factor and is related to the ratio of geometric dimensions. Given the geometry, you can find the Y value by looking at some tables. Y usually is close to 1.
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Your excellent teaching style is as rare as my frequency of creating a youtube comment. Thanks for the posted video.
Can't thank you enough for this great lecture. Wish you were my professor!
A highly cross-linked epoxy resin has a coefficient of linear thermal expansion α = 5×10−5
K−1, GIC = 120 J/m2, E = 3.2 GPa, and ν = 0.35. A thick layer of resin is cured and
is firmly bonded to an aluminum part (α = 2.5 × 10−5 K−1) at 180◦C. Calculate the
minimum defect size needed to initiate cracking in the resin on cooling to 20◦C. Take α in
Eqn. 5 to be 2/π for penny-shaped cracks of radius a in a wide sheet.?
Thanks for this short yet helpful video!
very high quality video lecture
It is true that fracture toughness is a specific value of stress concentration factor,though K(Kc) is not stress intensity factor,it is fracture toughness. If the material is broken(a fracture occured) we say that Kt(Stress intensity/concentration factor)>=Kc.
Can anyone explain the difference between the two equations for Fracture toughness equations such that:
K = (y.p)/(h.w^0.5) or
K= Y. STRESS.((Pi.a) ^0.5)
i think there is no difference between in two equation.
in first maybe you have a rectangular plate subjected to load P and have thickness, " h" & width ,"w" ..
so stress = P/(h×w) , h×w = C/S area of rectangle
you can put stress value in 2nd equation ..
but , K= y×(p/(h×w))×sqrt(PI×a) .. i got this equation( maybe i am wrong)
... sorry for my english ..
Is there any more videos on this subject? Iwin's law, Griffith's law?
Yes, just follow our channel and watch our AGENDA 2021!
@@adhesiveadvisor haha thanks for the reply, I passed this lecture 2 years ago! but I appreciate your video and work thanks a lot
th-cam.com/video/0r0ybJq0QRo/w-d-xo.html
@@ToddCoburn Professor Coburn!
Thanks for this great video!
is Y determined by the second moment theory of a bending beam?
i want to estimate the ideal thickness of borosilicate rod under Bending Stress, and to determine how the critical radius of a notch will change with the increasing of the rod radius.
how can i simplify it by this theory?
thanks in advance!
will there more videos... your teaching style is really clear
Yes, just follow our channel and watch our AGENDA 2021!
What are the formulae to determine stress intensity factor for all three modes for an edge crack on a turbine blade sujected to 3600 rpm rotation and temperature? Can anyone suggest relevant research articles. It will be really helpful.
Great explanation, thanks.
Thanks for a clear explnation!. How do we arrive at the crize size ..a for calculation. Ex In FEA , I get some hot spots and I know the magnitude of vonMises stress. How can I calculate the fatigue for such cases?
how do you calculate the critical crack length?E and Gc are given as is the maximum working tensile stress that the plate needs to withstand which is 400MPa.
E= 7.2 x 10^10 Pa
Gc= 6300 Jm^-2
Alex Quinn In a similar as any dimensioning in mechanics. Write up the equation for when it's just about to fail, and that would be when your crack is so long that the stress you have is enough to to crack your material. So just copy the equation and call your crack length a_C.
K = K_IC = Y*sig*sqrt(pi*a_C)
I’m confused in how you find a the geometric factor(Y). Do you need to know the flaw size in order to derive a value for it?
Is 'a' the initial crack length or the varying crack length. How does the testing machine determining the crack length calculates
the crack length, when it plots dA / dN vs DeltaK curve?
great.
good explanation. thanks
Does anybody know how to calculate the geometric factor with a sample of certain width??
th-cam.com/video/0r0ybJq0QRo/w-d-xo.html
did you figure it out, i need Y value rn for hw
What figure results would be considered a high fracture strength ?
Amazing.
thanks for that video
Thankss!!
dear dr
thanks for the lecture
i just have an equation
what condition must we take into account at the application of the k ?
Hi how is your day could you please tell me how can I contact you if I have question thanks 🙏
is crack or fracture must occur under plane strain condition?
No. Under plane stress condition crack also can propogate.
Jujur saya belum paham bagaimana memahami teori ini?
what is Y? it doesnt make sense
Y is geometric factor and is related to the ratio of geometric dimensions. Given the geometry, you can find the Y value by looking at some tables. Y usually is close to 1.
It's new science where the terminology are not well defined yet ! A lot of confusion ..
Lol it's a little funny to hear
what horrible ! there is not decent video about fractures?
Yes, just follow our channel and watch our AGENDA 2021!
annoying audio.