Open questions on the test job “bracket design”
Thank you for the test job. We have gone through the sketch of the bracket and the addendum with the requirements carefully and checked what CadPilot – an AI assistant that designs directly in CATIA V5 through an interface – can build from it. A few details are still missing for a reliable result. This page explains every question: what we need to know, why, and what a helpful answer can look like.
What we understood
- Bracket made of CR240LA GI40/40, sheet thickness 1.4 mm, minimum bend radius 2 × t = 2.8 mm, about 380 × 250 mm.
- Production-ready sheet metal part: base plate with embossed beads, z supports bent.
- Main load via the two lower collar holes Ø30 (4 mm collar): 30 kg in z (truck road load) and 5 g in y.
- The two central attachments (40 × 40 and Ø35 with a Ø10 hole, each 15° to the vertical) are “either/or” and stiffen a side wall in y – once on the left, once on the right of the truck.
- The three vertical beads (about 25 mm wide) are meant to act like an accordion in a rear crash.
- Spot welding: flange at least 20 mm, weld spacing at least 24 mm (shunting).
What already works
With today’s tools CadPilot creates the skeleton of the bracket exactly: attachment points, the planes tilted by 15°, the bead centre lines, bend edges, the spot welds with checked spacing and the load cases as a reference. On this skeleton a design engineer builds the finished sheet metal part in CATIA Sheet Metal. CadPilot does not yet build a production-ready sheet metal part itself, and it does not verify strength or crash behaviour – that remains the job of the calculation.
The quickest way to answer
- a dimensioned view with a coordinate table of the attachment points (A2, A3),
- a side view with the bends and weld flanges (A4, A5),
- a bead cross-section (B1),
- the installed position in the vehicle coordinate system, left and right (A1, B5).
A hand sketch with dimensions or a table is perfectly fine. Please quote the identifiers (A1, B3 …) in your answer. Where you do not have a value, “open” is enough – we then continue with a marked assumption.
Priority A – no meaningful model without these
A1 Coordinate system and installed position
How are X, Y and Z oriented, and where is the origin? What exactly do “rear”, “vertical” and “left/right in the truck” mean for the part?
Why: Every coordinate depends on it: the tilt of the two 15° attachments, the direction in which the collars are drawn, and the direction of the rear crash.
Example of an answer: Vehicle coordinates to company standard (X rearwards, Y to the right, Z up), origin in the left collar hole; or a view with the axis system drawn in.
A2 Dimensioned outline
What are the dimensions of the outline: all edges, tabs and cut-outs, ideally as corner points?
Why: The sketch is freehand; only 380 mm and 250 mm are dimensioned. Without the outline the AI would have to guess the shape – the result would not be reproducible.
Example of an answer: Table of the corner points P1…Pn with (x, z) in mm, or a dimensioned plan view; plus the radii of the outline.
A3 Position of the attachments
Where are the centres of the two collar holes Ø30, the 40 × 40 mounting face and the Ø35 seat with the Ø10 hole?
Why: These are the functional dimensions of the bracket; everything else is designed around them.
Example of an answer: Left collar hole (40; 0; 20), right (340; 0; 20); 40 × 40 attachment centre (190; 5; 230); Ø35 seat centre (190; 0; 140).
A4 z supports (flanges)
Which edges are bent as z supports, how high, at which angle and in which direction?
Why: The addendum asks for bent z supports; their geometry is missing from the sketch.
Example of an answer: Lower edge between the collar holes: 25 mm high, 90° rearwards; both side edges: 20 mm, 90° rearwards.
A5 Spot weld flanges
Which edges are spot weld flanges, to which mating part, and which edge distance applies to the welds?
Why: Only then can “flange ≥ 20 mm” and “weld spacing ≥ 24 mm” be applied and the number of welds determined: a flange of length L takes at most ⌊(L − 2e)/24⌋ + 1 welds (e = edge distance).
Example of an answer: Left and right side flange to the side wall, edge distance 10 mm; upper flange to the cross member.
Priority B – for a reliable result
B1 Beads
Where exactly do the three beads run, which cross-section do they have (is “t = 6 mm” the depth?, width 25 mm, flank angle, radii), in which direction are they embossed, and where do they end at the bottom?
Why: “t = 6 mm” is ambiguous, because t usually denotes the sheet thickness. The crash behaviour depends directly on the profile.
Example of an answer: Centre lines at x = 120, 190, 260 mm from z = 40 to z = 240; trapezoid 25 mm wide, 6 mm deep, flanks 30°, radii 3 mm; embossed rearwards, running out into the lower edge.
B2 Crash load case
In which direction does the “rear” crash act relative to the part, and which force level or deformation travel is the target?
Why: For an accordion effect, folding initiators usually lie across the crush direction; beads along the load direction rather stiffen until they buckle. Without direction and target the bead geometry cannot be designed on purpose.
Example of an answer: Crash in +X, i.e. along the beads; target: force level below 8 kN over 30 mm of deformation.
B3 Road load
Which load factor n_z applies to the 30 kg in z? Do the loads in y and z act at the same time or separately? How is the load introduced into the collar holes (bolt, bushing, bearing)?
Why: For the flanged holes and for the calculation. For orientation: 5 g in y give 30 kg · 5 · 9.81 m/s² = 1,471.5 N, about 736 N per collar hole if shared equally; the factor for z is missing.
Example of an answer: n_z = 3 (truck specification ch. 4.2); y and z separately; introduced via an M12 bolt with a Ø28 spacer sleeve.
B4 Central attachments
Which loads go into the side wall via the 40 × 40 face and the Ø35 seat? Are the faces raised or recessed, and by how much? About which axis are they tilted by 15°?
Why: The addendum only says that they stiffen the side wall in y; shape and position are not specified.
Example of an answer: 2 kN in y each; both raised by 8 mm; tilt 15° about the X axis, top rearwards.
B5 Same part left/right
Is the bracket one part that is installed on the left and on the right of the truck, with only one of the two central attachments used on each side?
Why: That is how we understood “once on the left and once on the right”. It fixes how collar holes, flanges and beads must lie relative to the vehicle centre.
Example of an answer: Yes, the same part; on the left the 40 × 40 face carries, on the right the Ø35 seat.
B6 Collar holes
Is Ø30 the final inner diameter after drawing, or the pilot hole? From which side are the 4 mm of collar height measured?
Why: This is the manufacturing dimension of the flanged hole; the two readings give different parts.
Example of an answer: Ø30 H11 inside after drawing, collar 4 mm from the rear face of the sheet.
B7 Small holes
How many small holes and slots are there, with which dimensions and where?
Why: The sketch shows 6 to 8 of them, all without dimensions.
Example of an answer: 4 × Ø6.5 in the upper tabs, 2 slots 8 × 14 in the left tab; position as coordinates.
Priority C – for the acceptance
C1 Surroundings
Are the surroundings available as STEP (side wall, mating parts, neighbouring parts)?
Why: Then clearance and weld flanges can be checked against the neighbours instead of just being asserted.
Example of an answer: STEP of the left side wall and of the cross member, vehicle coordinates.
C2 Expected result
What should be delivered at the end (CATPart with sheet metal features, flat pattern, STEP, drawing)? Which naming convention, which tolerances, which target mass?
Why: This decides when the job is done.
Example of an answer: CATPart with Generative Sheetmetal Design, flat pattern as DXF, STEP; name by part number; target mass below 1 kg.
C3 Formability
In which tool direction is the part drawn, and which drawing depth is allowed for the beads in CR240LA at 1.4 mm?
Why: Production-ready also means formable. That can only be judged with forming simulation or experience – CadPilot cannot do it.
Example of an answer: Tool direction −Y; bead depth up to 7 mm according to the tool shop guideline.
The examples are made up and only show the form of an answer.
What happens next
With the answers to A1 to A5, CadPilot builds the skeleton model in stages, each checked by a design engineer. The answers to B and C go into the beads, the spot welds and the load cases. The result always includes a list of the assumptions made and of the deviations from the job.
Please send answers and questions to Martin.
