FMVSS 202A Introduction
Note: “H/R” here should be read as “head restraint.”
This procedure is based on the FMVSS 202A. FMVSS 202A contains two compliance options: Static and Dynamic.
Here we would specifically addresses Section S4.2.7 of the static compliance option: ‘Backset retention, displacement,and strength.’
Energy absorption (S4.2.5), height retention (S4.2.6), and initial displacement at 37 N-m (S4.2.7(a)(1)) are not covered in this short procedure.
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Some requirements of 202A
a) Seat back shall be rigidly held during the backset retention (37 N-m) and displacement (373 N-m) portions of the test.
b) For adjustable seat backs, the seat back shall be adjusted to a position that results in a 25° torso angle.
c) Back set retention requirement is 13 mm, as compared to 10 mm in the proposed 202A.
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Short flow chart depicting procedure
1) Position Head Restraint
2) Position Seat Cushion
3) Install Back Form and Position Seat Back
4) Establish Displaced Torso Line(373 N-m moment on back form)
5) Create Seat Back Bracing
6) Install Head Form and Measure Non-Structural Displacements
7) Head Restraint Displacement Requirement (373 N-m moment on head form)
8) Head Restraint Set Requirement (Backset retention at 37 N-m)
9) Remove Seat Back Bracing
10) Head Restraint Strength Requirement (890 N head form load, minimum)
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Input Definition
Set-up information (seat position for 202A testing, 202A torso angle, seat back bracing)
Requirements (acceptance criteria)
Proper CAD.
Lower Structure modelling
Previous experience points to the fact that the lower structure is not the weak link during ultimate loading of the H/R.
Hence, it may be possible to remove some or all of the seat lower structure from the FE model without significantly affecting the results. This can improve convergence and reduce run time.
Note: “H/R” here should be read as “head restraint.”
This procedure is based on the FMVSS 202A. FMVSS 202A contains two compliance options: Static and Dynamic.
Here we would specifically addresses Section S4.2.7 of the static compliance option: ‘Backset retention, displacement,and strength.’
Energy absorption (S4.2.5), height retention (S4.2.6), and initial displacement at 37 N-m (S4.2.7(a)(1)) are not covered in this short procedure.
--------------------
Some requirements of 202A
a) Seat back shall be rigidly held during the backset retention (37 N-m) and displacement (373 N-m) portions of the test.
b) For adjustable seat backs, the seat back shall be adjusted to a position that results in a 25° torso angle.
c) Back set retention requirement is 13 mm, as compared to 10 mm in the proposed 202A.
---------------------
Short flow chart depicting procedure
1) Position Head Restraint
2) Position Seat Cushion
3) Install Back Form and Position Seat Back
4) Establish Displaced Torso Line(373 N-m moment on back form)
5) Create Seat Back Bracing
6) Install Head Form and Measure Non-Structural Displacements
7) Head Restraint Displacement Requirement (373 N-m moment on head form)
8) Head Restraint Set Requirement (Backset retention at 37 N-m)
9) Remove Seat Back Bracing
10) Head Restraint Strength Requirement (890 N head form load, minimum)
-------------------------
Input Definition
Set-up information (seat position for 202A testing, 202A torso angle, seat back bracing)
Requirements (acceptance criteria)
Proper CAD.
Lower Structure modelling
Previous experience points to the fact that the lower structure is not the weak link during ultimate loading of the H/R.
Hence, it may be possible to remove some or all of the seat lower structure from the FE model without significantly affecting the results. This can improve convergence and reduce run time.
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