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Workshop 3- Structural Equivalency Spreadsheet (SES) Document Review

Speaker I Ting-Wei, Lin; Yu-Cheng, Wu

Editor I Yi-Shan, Hsiao

​Publication time: Feb. 29 2024

This physical workshop was held at the Pioneer International R&D Building of Taipei University of Technology. Lin Tingwei, the former captain of Tsinghua University, and Wu Yucheng, the former frame team leader, introduced the SES file in the FSAE rules. The purpose of SES, filling techniques, common mistakes of the team, and the experience of filling in the Monocoque SES document when the Tsingta University team participated in the German race will be introduced in sequence.

Introduction to SES

What is SES?

Structural Equivalency Spreadsheet (SES) is the structural equivalent specification table in the FSAE rules. Through SES, it can be confirmed that the main structure of the frame meets the minimum requirements of Chapter F of the FSAE rules.

According to FSAE rules F.2.1.2, SES will document the calculation of the primary structure of the frame, prove that the design complies with FSAE rules, and confirm equivalence with FSAE rules under a common benchmark.

SES purpose?

  1. In the early design stage, structures that cannot meet the rules are discovered and corrected, and SES filling and frame design must be "synchronized."

  2. Avoid making frames that cannot meet the rules, resulting in a waste of time, money, raw materials, and manpower.

Why is SES important?

  1. The main structure is the final guarantee for rider safety in the event of an accident.

  2. Failure to pass SES means that the "minimum requirements for frame safety" in the FSAE rules are not met.

Highly recommended......

  • Read the rules before designing.

  • Frame designPeriod and production period must be "duplicate"Confirm the rules!

  • Write SES early!

  • Prepare materials in advance

  • Always prepare a plan B in case SES fails, for example: prepare more ingredients. "Don't think it will be over once and for all!!!!"

What does poor SES completion mean?

✖️Poor layout and overlapping pictures>>

All titles and text descriptions should be placed neatly for easy reading. Please do not overlap pictures.

✖️Pictures and text are too small/too large and have poor proportions>>

The size of pictures and text should be about the same size as the original content

✖️Does not match the designated picture>>

Pictures should be placed in the officially designated items, and other supplementary pictures should be placed downwards

✖️The picture has no text explanation and no title>>

Please put the picture in the same column. When supplementing pictures, try to add titles and text descriptions so that the judges can understand what you want to add.


For more examples of poor filling in, see the video at 00:12:31

Monocoque SES

Nowadays, more and more teams are trying to make a monocoque. Compared with the traditional steel tube frame, the content of the monocoque SES may be more than 20 times (depending on the design complexity)


Roughly speaking, the contents of the monocoque SES can be divided into three aspects: partitioning of the monocoque, partition strength, and locking point strength.

Partition layout and testing

The concept of partitioning is similar to that of transmission steel tube frames (such as SIS, MHB, etc.). Each partition may have a different composition (layup), also known as a sandwich structure, which may vary from the outermost carbon fiber to the innermost aluminum air nest. Different layouts require corresponding partitions and tests.

The test requires at least three-point bending test and shear test. The test results must be compared and calculated with the steel pipe test results.

  • The purpose of the three-point bending test is to obtain Modulus and Ultimate Tensile Strength

  • The purpose of the shear test is to obtain the Ultimate Shear Strength (which will be used to derive the locking point strength later)

Partition strength

There is no leakage, no exhaust, no disassembly, no rupture and no fire, and the open circuit voltage of each test cell or battery pack after the test is not less than 90% of its voltage before this test.

The first:Directly take a range of equal width as a flat plate, and remove the openings in the specified area. This is the most conservative approach.

The second type:Some layups may not be simply flat plates, but may have large curvatures. In order not to ignore too much structural strength, the cross-sectional inertia can be calculated to equal steel pipes with the same cross-sectional inertia.

The third type:The most complex, usually used when the shape design is too special, such as a non-complete curved surface with non-locking holes. You can use a method similar to the first one, using flat plates of different widths to collage.

Lock point strength

In addition to the locking points connected to steel pipes such as the front hoop (FH) and main hoop (MH), it also includes locking points to the battery box, seat belts, anti-collision blocks, rear anti-collision, etc. The installation of the locking point strength test must also be consistent with the actual situation, such as the direction of force or the fixing method, such as Free Edge.


Lock point classification

Divided into Skin-Insert-Skin and Single Skin/Chamfer:

  • Skin-Insert-Skin: Insert is placed in the mezzanine, with locking lugs on one side and a backing plate similar to a gasket on the other side. High strength, usually used in connection with steel pipes

  • Single Skin/Chamfer: There is no interlayer at the locking point, only Skin, such as carbon fiber, with a spacer on each side. Lower strength but lighter, usually used in purely fixed positions.

Activity photos

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