Aung

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1 years, 143 days

MaplePrimes Activity


These are replies submitted by Aung

@mmcdara Yes sir ..it is an indeed viscoelastic problem. thank you i have experimental data and i'm gonna try like the guidelines you described. actually..i already fit the data using NonLinearFit command but i'm a little bit not faimliar with numberical calculation or optimization problem behind the sense..so i try to get this..thank u Sir.

@acer Sir, i have the same solution to this..this is right...but can you use a little simpler command..i mean i don't understand behind the idea of this line
temp := subsindets(temp, specfunc({specfunc(sum),name=range},int),
                   u->Sum(Int(op([1,1],u),op(2,u)),op([1,2],u)));

@Preben Alsholm Sir ..what you mean is that ..it can be used directly in the model and without changing to standard function we can get the values of k from curve fitting?..right?

@Preben Alsholm thank u Sir
i just want k as symbolic parameters..is there any other way k is as symbolic k?

@dharr thank u Sir.

 i don't know k , k is a material constant and i actually think k can be get from curve fitting .(may be i'm wrong)...and can we get standard functinos ..with k symbolic...

@Scot Gould Sir.... actually...the equation is like this......this is the governing equation for damage accumulation model of composite under fatigue loading...i consider with sinusodial loading case
  i have some derivation...dD/dt = some function and....finally we get   

D(t) = 1-(1-C(1+k) integral 0 to N (sigma_a * sin(omega*t))^k dt........

if i can get closed form solution..i can plot damage accumlation vs number of load cylce ...
and and loading parttern is a choice .. ....i can get closed form with different type of loading history..for eaxmple ( constant trapezodial pattern)..but sinusoidal loading are actually easy and cheap to set up  experiment and ...the problem is i don't get closed form solution for integral term.

@Preben Alsholm Sir.... actually...the equation is like this......this is the governing equation for damage accumulation model of composite under fatigue loading...i consider with sinusodial loading case
  i have some derivation...dD/dt = some function and....finally we get   

D(t) = 1-(1-C(1+k) integral 0 to N (sigma_a * sin(omega*t))^k dt........

if i can get closed form solution..i can plot damage accumlation vs number of load cylce ...
and and loading parttern is a choice .. ....i can get closed form with different type of loading history..for eaxmple ( constant trapezodial pattern)..but sinusoidal loading are actually easy and cheap to set up  experiment and ...the problem is i don't get closed form solution for integral term.

@aroche it's still show integral..not solution...here is the problemintegral.mwintegral.mw

@Preben Alsholm yes.Sir..but please check this equation.....
d(n)=int( (sin(omega*t))^k,t=0..N
i have eqautino like this...and maple didn't solve that equation by default...is that maple crack..or this eqaution doesn't converge....is there any other way..to solve this eqaution

@acer yes.Sir..but please check this equation.....
d(n)=int( (sin(omega*t))^k,t=0..N
i have eqautino like this...and maple didn't solve that equation by default...is that maple crack..or this eqaution doesn't converge....is there any other way..to solve this eqaution

@Preben Alsholm thank you sir...but in my problem k is parameter have to decide..from experimental data with curve fitting..is there any way..to solve symbolically with k prescence...N is loading cycle ...and n is cycle to failure ..this is cyclic loading problem....
the problem is k is material constant.....can you help ..without getting rid of k....MaplePrimes24-04-04_int_bug.mw

i go to the axes properties. and used tick marks..it doesn't change..can you please check my plot here is my m.file

45.mw

@mmcdara 
thank you Sir...i got it...i need intital guess values from some paper and sovle it form what your guided model...and it help me a lot  ...here is mine...it is pretty valid i think and need to verify that from my supervisor
By the way...this is the prediction of stress-strain curve of unidrectional composite laminate under strain rate loading....yours are quite helpful......than you very much...Sir..wish you the best

@mmcdara thank you sir...i'm a student  and...this is for my thesis..sir..actually i don't have ...enough data for intital value..here is the error is reduced..but still too high....that you very much..sir..yours ..is absolutely helpful
9terms.mw
can you check please...look like need to determine.constraints..more effectvely?
that you very much sir

@mmcdara 
thank you sir....e  is exponential..and G values are prony coefficient and tau values are relaxation times...
should i put e and nu(poission ratio) to parameters..poission ratio is given and e is exp...
can you give me how to put intial point to maple worksheet...i already tried intital points also...but still some error for this.
here is my maple worksheeet..sir....i really appritiated that.prony.mw

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