Hi All,
I lead a mechanical team at a growing aerospace company building small satellites up to 500 kg. I've been tasked with bringing structural analysis in-house to rely less on outside contractors. I intend to accomplish this through a mix of training and hiring, but I am concerned about the learning curve required to build accurate but efficient FEA models with such a young team - only I have significant structural analysis experience (~5 yrs) and even so I'm not really a SME.
I know there is some art to FEM building, and training will take time. My nightmare scenario is a poorly built FEA model that gives spurious modes, stresses, and/or bolted joint margins, which we don't discover until the spacecraft is on a vibe table. Best case scenario we would then have to scramble to recompute the notching plan while we burn money at the test facility. Worst case would be damage to the spacecraft and that is simply not an option.
So I want to be able to confidently vet our FEA models. Having experienced outside analysts review our models is expensive long term and only goes so far. From what I've seen, even the most experienced teams of analysts are routinely off on first modes by ~10%. Without observational data there are always uncertainties. So in my mind the only reasonable means to verify FEM accuracy is testing. We strongly prefer to be able to test in-house, but we don't have the capital for a vibe table of sufficient size. My sights have been homing in on modal testing as the most cost- and time-efficient way to verify our FEMs. My thinking is to purchase a large granite table as the fixture, acquire modal testing equipment, train our analysts through an iterative FEM building - testing - correlating process on subassemblies as we build our next few spacecraft, establishing the best practices for bolted joints and other modeling aspects particular to our buses. Then we would perform additional modal testing on the integrated spacecraft, correlating the vehicle-level model and confirming our notching plan long before the vehicle is at the test facility.
Is this sensible thinking? Am I being overly skeptical of FEA models and will this be a waste of resources? Is there some other type of testing or approach to model verification that would be more appropriate?
TL;DR - I'm trying to build a structural analysis team from scratch and want to make sure our FEA models are accurate. What is the best way to do this?
I lead a mechanical team at a growing aerospace company building small satellites up to 500 kg. I've been tasked with bringing structural analysis in-house to rely less on outside contractors. I intend to accomplish this through a mix of training and hiring, but I am concerned about the learning curve required to build accurate but efficient FEA models with such a young team - only I have significant structural analysis experience (~5 yrs) and even so I'm not really a SME.
I know there is some art to FEM building, and training will take time. My nightmare scenario is a poorly built FEA model that gives spurious modes, stresses, and/or bolted joint margins, which we don't discover until the spacecraft is on a vibe table. Best case scenario we would then have to scramble to recompute the notching plan while we burn money at the test facility. Worst case would be damage to the spacecraft and that is simply not an option.
So I want to be able to confidently vet our FEA models. Having experienced outside analysts review our models is expensive long term and only goes so far. From what I've seen, even the most experienced teams of analysts are routinely off on first modes by ~10%. Without observational data there are always uncertainties. So in my mind the only reasonable means to verify FEM accuracy is testing. We strongly prefer to be able to test in-house, but we don't have the capital for a vibe table of sufficient size. My sights have been homing in on modal testing as the most cost- and time-efficient way to verify our FEMs. My thinking is to purchase a large granite table as the fixture, acquire modal testing equipment, train our analysts through an iterative FEM building - testing - correlating process on subassemblies as we build our next few spacecraft, establishing the best practices for bolted joints and other modeling aspects particular to our buses. Then we would perform additional modal testing on the integrated spacecraft, correlating the vehicle-level model and confirming our notching plan long before the vehicle is at the test facility.
Is this sensible thinking? Am I being overly skeptical of FEA models and will this be a waste of resources? Is there some other type of testing or approach to model verification that would be more appropriate?
TL;DR - I'm trying to build a structural analysis team from scratch and want to make sure our FEA models are accurate. What is the best way to do this?
