6. Summary of results

% differences/reference

Clean mode order	Reference NAFEMS	Aster
Test 0 »	Aster Test1	Aster Test2	% diff. Test0	% diff. Test1	% diff. Test2
1	0.421	0.4178	0.4178	0.4165	0.4163	—0.76	—1.07	—1.12
2	1.029	1.0255	1.0255	1.0301	1.030	1.0340	0.34	0.11	0.49
3	2.582	2.5669	2.5793	2.5793	2.5644	—0.58	—0.10	—0.68
4	3.306	3.2733	3.2733	3.2572	3.2539	—1.47	—1.47	—1.58
5	3.753	3.7347	3.7347	3.7397	3.7433	—0.49	—0.35	—0.26
6	6.555	6.5236	6.5236	6.4544	6.4544	—0.98	—1.54	—0.99

% differences/reference

Clean mode order	Reference NAFEMS	Aster
Test 0 »	Aster Test1	Aster Test2	% diff. Test0	% diff. Test1	% diff. Test2
7		7.3756	7.2821	7.2821	7.2119		—1.27	—2.22
8		7.7332	7.6852	7.6852	7.6026		—0.62	—1.69
9		8.5567	8.3764	8.3764	8.3232		—2.11	—2.73
10		11.1199	10.7209	10.7209	10.7735		—3.59	—3.12
11		11.6474	11.2904	11.2904	11.2607		—3.07	—3.32
12		14.3551	13.7573	13.7573	13.3008		—4.16	—7.34

• For tests 1 and 2, the quadrangles on sheet NAFEMS were cut into triangles.

Tests 3 and 4 can be done by*Aster (no quadratic shell element).

• Up to the 9th mode, the frequency error is \(\text{≤ 2.5\%}\).

• The mesh distortion effect only really appears on modes 7 and 12.