I wanna to analyse a low velocity impact procedure on composite pressure vessel, but I don't know what analyse I should be do. Can anyone help me?
Quasi-static load means the load is applied so slowly that the structure deforms also very slowly (very low strain rate) and therefore the inertia force is very small and can be ignored. A dynamic load, on the other hand, casues a structure to vibrate and the inertia force is big enough and must be considered.
Impact involves a load quickly applied over a short time duration.
Conventional dynamics analysis and impact analysis are different. You have to choose the right steps/keywords in a commercial software package.
Quasi-static load means the load is applied so slowly that the structure deforms also very slowly (very low strain rate) and therefore the inertia force is very small and can be ignored. A dynamic load, on the other hand, casues a structure to vibrate and the inertia force is big enough and must be considered.
Impact involves a load quickly applied over a short time duration.
Conventional dynamics analysis and impact analysis are different. You have to choose the right steps/keywords in a commercial software package.
so useful professor
I am modelling the pressure vessel in Abaqus so I can analyse the low velocity impact and it is not important what type of them. is it true?
Low velocity impact means that deformation (plastic) is allowed to occur during the impact as it is lsow in comparison.
High velocity impact means that it happens so fast that deformation barely develops during such a short time duration and hence fracture occurs.
So these two types of impact are different and should be analysed differently. LS-Dyna deals with high velocity impact. I think Abaqus deals with low velocity impact but I do not know whetehr it deals with high velocity imapct too.
Hi: in a qusi-static approach you consider an aditional static force to model the dynamic phenomenon, but you are actually running a static model, without any integration in time or modal analysis. For example: in a quasi-static analysis of a slope subjected to an earthquake, you consider a horizontal additional force in the equilibrium of forces. The key thing is how to obtain this equivalent aditional force to get accurate enough solutions, and there is where these methods, extremely simplistic, usually fail.
Hi every body. To be sure that is really quasi static problem you should compare eigenfrequency of you structure with frequency of loading. If eigenfrequency about ten times grate of loading frequency it may be a quasi static problem. In another way it is a dynamic problem.
In case of pressure vessels you need to follow the maximum allowable loads according to some standards either ASME or DIN. The main difference will be either you want to include inertia forces or not. This mainly depends on which type of analysis you want to perform.
Quasi-static load means the load is applied in slow rate like static load (very low strain rate). A dynamic load, causes a structure to vibrate and the inertia force is considered.
Loading types are dependable on many factors like time between each applied load.
- -static load : Applying the load very slowly which means that stiffness forces of the structure (Force=Displacement * Stiffness) are governed not inertial forces ( Force = Mass * Acceleration ) as the load is applied very slowly acceleration =0
- -Cyclic Loading : Applying the load more than once. If the the frequency of applying the load is small.
- --Quasi -Static: Loading could be Quasi-Static which means that there is acceleration of applying the load but it is very small and it can be neglected. Quasi- static means that there is dynamic effect but it is very small that leads to consider the system as if it is static but it is not.
- -- Dynamic : If the cyclic loading is applied in quick manner and in a small duration. Inertial forces are induce. As the mass particles in the system move which means Newton Second Law of motion is validated. F=m*a addition force is induced additional to static load,
I find the main difference between quasi static and dynamic analysis is the removal of the time inertia features which means one can carryout time integration but one removes teh density times mass term. Thsi is quite easy to do in Abaqus.
Mohamad Khorashad ....Please check references below.. hope it will be helpful for you…
Regards…
http://www.iaea.org/inis/collection/NCLCollectionStore/_Public/26/045/26045516.pdf
https://studentcommunity.ansys.com/thread/static-quasi-static-dynamic-transient/
- Badges
- Science topic