I am working on structural analysis of an RC plane in a symmetrical maneuver. There are two types of loads on the structure a) aerodynamic loads and b) inertial loads.

I have determined the aerodynamic loads by performing CFD analysis on Fluent. Mapping of aerodynamic loads from CFD mesh to structural mesh in MSC Patran is easy. The details of the load mapping are given in link [1].

The maximum inertial loads in any maneuver can be determined using analytical calculations or directly from different handbooks/standards including FAR 25 etc.

I have read somewhere that I can perform static analysis of unconstrained system using inertia relief. However, from what I have learnt from link [2], the inertial loads cannot be used in inertia relief analysis.

Question#1: Is it possible to perform the static structural analysis of an unconstrained object subjected to aerodynamic loads (which are nothing more than a pressure distribution) coupled with inertial loads? If yes, how?

Question#2: If static structural analysis cannot be performed, do I have to perform a dynamics analysis?


1- https://www.eng-tips.com/viewthread.cfm?qid=446687

2- https://pdfs.semanticscholar.org/6e7c/9a0ba36d86ac73b3e2e213fa64e3b6c5b988.pdf

  • $\begingroup$ By "RC plane" you mean "radio controlled aeroplane," not "reinforced concrete slab", right? With the title and tags I was expecting the latter... $\endgroup$
    – AndyT
    Oct 14, 2019 at 14:38
  • $\begingroup$ @AndyT yes, I mean remote-controlled plane. $\endgroup$
    – Ali Baig
    Oct 15, 2019 at 14:16

2 Answers 2


Q1- No you cannot simulate a static simulation without any constrains, you need to define a constraint with respect to which calculations will be conducted. I would suggest calculating all the forces in frame of the body, and then put it to rest and perform static structural analysis.

Q2- It is your choice if you want to do a dynamic analysis, that totally depends on your need and skills. You can go for static analysis if you can define the forces, drag, etc with respect to the plane, i.e in the lagrangian domain and not eulerian.

Obviously, if you conduct a dynamic analysis that will convey a more clear picture and be of more use to you with regards to information and reliability.


Question#1: Is it possible to perform the static structural analysis of an unconstrained object

Yes this is possible, it is called "inertia relief". It creates a state of static equilibrium by automatically applying forces/moments at the center of mass (or a specified node), such that the net force/moment on the structure is exactly zero. Note that as this is still a static analysis, the assumption is that the acceleration of the object is zero. If you have an unconstrained object that is accelerating, then static analysis is not possible.


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