Recent content by Vigardo

In 3D happens something similar, M=6, R=12 and J=6, and thus M+R>=3J (18 = 18). It is evident that this 3D truss it is not stable because the vertical member will rotate easily due to the lack of restraints. I need a "recipe" or sequence of simple geometrical checks or rules that work in all...

Dear experts, I´m searching for some method to determine whether any 2D or 3D truss is stable without solving complex matrix equations. I want to implement such method in a simple computer program to discard any a priori non-stable trusses for further analysis. Do you know any book or...

Thanks @jrmichler for your detailed response! I´m already aware of such failure mechanisms. It is good to know that Aircraft Structures (by Peery) deals with all of them. In ASCE 13 (page 887, link above), there are provisions about Nailing to HSS, which in essence is what I´m trying to do, but...

I´m sorry, I borrowed the figure somewhere. For example, the wall thicknesses of my connections would range from 3 to 10 mm and the diameters from 10 to 25 cm. The relative bolt size should be also much smaller than it can be seen in the figure. In any case, I´ll take into account your...

Sorry, in principle, it just must withstand tension and compression along the axis of the tubes. Thanks!

You´re right they are really cheap. Thus, I bet their very low efficiency should be the reason:. In this link their efficiency is discussed. It seems not easy to calculate, as it depends on thermal difference, but I think it can´t be over 5 or 10% in practical designs.

Thank you very much! I´ve found this thread about Bolting through Hollow Square Sections (HSS) in the eng-tips forum you´ve indicated. There are provisions for Through-Bolting to HSS in Section 7-13 of the AISC 13 (pages from 885). More about connecting HSS members with through-bolts here...

Probably you have already thought about this and/or it may be a bit out of the topic, I´m sorry if so. This thread is about using a compressor for cooling, but what about using Thermoelectric Cooling (i.e. Peltier cells) instead? Despite it would be much less efficient than a properly tuned...

Dear experts, thanks in advance for your kind help! I have not found any provision or rule for designing bolted sleeve connections in EC1993-1-8 (Eurocode 3: Design of steel structures - Part 1-8: Design of joints) like the one shown in the figure: I have just found some research paper about...

Thanks for your kind recommendations they are very helpful! In essence, I've performed what you said but "mentally" :smile:. After deeply thinking about it I think I have some reasoning that would explain the number of close-to-zero modes differences between buckling and modal analyses. Would...

Your solution works! Thank you very much Jrmichler! This is the first not-close-to-zero buckling mode using one central support with all DoFs fixed and 12 very soft springs (0.1 kN/m springs for 101 kN/m2 hidrostatic pressure). Buckling factors and Normal modes frequencies are also shown...

Dear FEA experts, I'm trying to model the mechanical behavior (static, modal, and buckling analyses) of an underwater floating structure (e.g. submarine capsule or buoy) under hydrostatic pressure by Finite Element Analysis. To obtain feasible results, the structure should be modeled as freely...

You're right, perhaps I'm overthinking here. I will use the finer mesh for my calculations and not worry about the coarser mesh artefacts anymore. In fact, the finer mesh buckling factors are not so different (90 and 87) for both mesh types. Thank you very much for your kind explanation!

Dear FEA experts, I’m trying to analyse* some finite elements model of a thin walled cylinder with variable cross-section, but I’m observing four weird issues in the buckling modes. The structure is vertically (along z-axis) and horizontally (along y-axis) loaded on top. Would you help me to...

Hi Harini, if in the beverage there are many different substances, some of the methods above cited will hardly work or be very expensive. If very tiny quantities would be taken (micro-litres), you would try mass spectrometry. This in not strictly "non-intrusive", but it would do the job for a...