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Hi

well if you want to apply an acceleration load (i.e. a "space-craft launch load") you typically apply an acceleration field, in the harmonic mode (equivalent to apply a gravity acceleration field as for a static gravity sag analysis:

define constants:

G0= 1[lbf/lb] or just = 9.81 [m/s^2]

gravity sag in "smsld":

static mode, Load on subdomain Fz = G*rho_smsld


define a function

Acc (freq) = amplitude spectrum of your acceleration over desired frequency domain

In harmonic mode: parameter "freq" from 10 .. 500 Hz with TBD defined resolution

apply sub-domain load F = acc(freq)*rho_smsld


and off you go. Do you catch tha analogy with the ravity field case at feq=0 (i.e. static) ?

Its easy no? once you think about it, just apply your physics, that is what COMSOL is about, but you do not have all your physics predefined, as in most other FEM codes, this gives you far more freedom and allows to do thing not easily possible before

Good luck
Ivar

Dear Ivar,

How to apply acceleration in Time-domain analysis. I also understand 'gravity sag in "smsld"'

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RUBAN SUGUMAR

Hi

you need to be more precise: what kind of acceleration ?

Gravity = volume force as "rho*g_const" ?
rotational acceleration, boundary forces ...

In fact normally you do not apply directly an acceleration but rather you define a load of some kind of the type "rho*a" on each element dx*dy*dz of a domain or boundary

And do you accelerate the fixed boundary ? if so you have to check your equation because fixed and acceleration is not really compatible ...

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Good luck
Ivar

hi
I am trying to check the result after applying g in piezoelectric energy harvester kindly help i am very new to comsol