Hi,

I have a concern regarding the stress analysis on the bracket I have designed.

The bracket is carrying Horn Antenna Assy which is then fixed to the Master Block . Then the entire Assy is purely under Gravity due to its own Mass.

The weight of the Assy is 3.5Kg including Bracket.

I have done some analysis on this assy applying gravity as loading condition and providing the Fasteners from the Connector facility in solidworks.

I have used AISI 304 Steel Alloy for the Fastener Material.

I am veryfing whether the Bolt assy is within the defined Factor of safety or not.

In case1: I have applied preload strength data in solidworks for bolts as 2.5Nm torque with deifned FOS of 2. In this case I got a factor of safety of ~5. Which is a good sign of strength.

In case2: I have applied preload strength data in solidworks for bolts as 4.2Nm torque with deifned FOS of 2. In this case I got a factor of safety of < 2. Which is not acceptable within this very small increase of torque value.

Can some give me some explanation whether I am performing the correct method for the analysis or not.

Appreciate the feedback.

Thanks

Vijay

Hi.

A picture of the problem would of course be nice to understand it better. (dimension of the bolts, bolt direction and distances compared to the COG-load to understand axial, shear and bending moments).

My knowledge is poor on how to properly use the safety factor and the "safety check plot" with bolt connectors in SW Simulation. Since you normally preload the bolts, lets say up to 75-90% of its proof load strength it is kind of hard to reach a FOS of 2 or 3 on each bolt. Especially if you use yield limit as "bolt strength" and have other loads that imposes shear, bending moment or additional axial loading to the bolt. I always set FOS = 1 as the limit for each bolt in the "strength data" section and then look at the combined FOS for the bolt pattern. Hand calculation is also a good idea.