Originally Posted by GTM_Challenge
Originally Posted by rzm3
I am sorry but what you said makes no sense.
When the safety harnesses are pulled towards the front of the car (e.g. during an impact), they create a mechanical moment around the B pillar mounts, which will "pull" the horizontal bar forward (think of turning a wrench towards the front of the car). The downward bars, however, will oppose this forward "pull", hence putting the bars in compression.
(the B pillar mounts will generate an opposing moment as well against the forward pull of the harnesses, but obviously that is not sufficient; because otherwise you would not even need the downward bars)
I'd be happy to draw a free body diagram and do a summation of moments around the B pillar mounts if you'd like.
The bar is lower than the harness holes in the seat, as it should be. The harness when being pulled isn't being pulled directly downward because of this. I have seen a good number of harness bars where the harness bar is higher or at the same level as the seat holes which is not ideal.
The main bar is triangulated by the 2 vertical rods ( 5/8") OD steel. While they see a load it is not the only part that bares a load and how much load depends on the angle of the pulling force (harnesses). Either way, under compression or tension, the vertical tubes would need to see massive forces to buckle them beyond what a human body could sustain.
Regardless, I am confident in the design our fabricator has put together and is consistent with other successful designs he has done in the past for years as well as other manufacturers have done in the past.
Just my 2 cents on a life safety item....
Based on the OP pictures in the E92M install, it appears when the harness is under load, the harness bar (if without the small diameter kicker rod brace) will tend to rotate counterclockwise (down) about the pillar connection as others have mentioned. Therefore, the kicker rod brace will then act in compression to resist this rotation.
I do not see how in most applications where the harness would be at a sufficient upward angle to cause the harness bar to rotate clockwise (up) about the pillar connection.
In my opinion, if the kicker rod bracing is subjected to a high compression load (in a high impact accident when you need it the most), the buckling capacity will be insufficient as it will be relatively quite low due to the long length and small diameter. Not to mention the compression capacity will be further reduced if there are end connnection eccentricities or any concealed defects (small kinks and dents) in the rod.
Again. Just my 2 cents on a life safety item......