Its core competence is manufacturing — welded steel fabrication, upholstery, and seat assembly at scale — with a small engineering group whose day-to-day work is 3D modelling rather than structural analysis.
When the OEM won a national rail-operator tender to design and produce a new intercity coach seat programme, the scope needed external expertise. The seat had to satisfy the full mechanical envelope of UIC 566 — the international standard for railway seat structures — while meeting a contract mass limit that the standard alone does not impose.
With the tender awarded and production deadlines fixed, the OEM needed a partner able to take the seat from a styling model through detailed mechanical design, composite material selection, laboratory characterisation, structural verification, and full manufacturing documentation. They engaged eCon to run all four workstreams under a single delivery.
Composite structural design is a specialised discipline in which material selection, coupon testing, and finite-element analysis feed each other: the input to each stage is measured instead of looked up.
Rail-sector fire-resistance requirements compound this — the flame retardant needed in the polyester matrix raises the resin's viscosity and reduces LRTM processability — so material choice cannot be settled without early bench work upstream of the design itself.
Starting from the client's styling model, eCon developed the complete engineering design of a welded steel-tube frame, a glass-fibre reinforced polyester composite seat body attached through embedded metal inserts, an aluminium (ADC12) folding armrest with its hinge mechanism, a PA6+30% GF folding table, and the seat-, backrest-, and headrest-adjustment mechanism. Non-structural mouldings and the outlet panel housing the mains and USB sockets were integrated into the same set. The output was a complete manufacturing-ready package, not an analysis handed off for someone else to complete.
The composite seat body is built as a laminated shell — unifilo glass-mat reinforcement across most of the surface, with biaxial glass reinforcement added locally where loads concentrate. The body is manufactured by Light Resin Transfer Moulding (LRTM), and the matrix is BÜFA FIRESTOP 8175-W-1, a fire-retardant unsaturated polyester chosen to meet the sector's fire requirements while remaining LRTM-processable. The trade-off between retardant loading and mould-fill behaviour was resolved before layup design began, so that the subsequent structural work was based on the actual manufacturing candidate rather than a theoretical laminate.
Coupons of both the unifilo and biaxial laminates were manufactured and tested at eCon's own materials laboratory. The linear anisotropic parameters used in the finite-element model — in-plane and through-thickness moduli, shear moduli, Poisson ratios, and tensile strength — were derived directly from those measurements. This is the step routinely skipped when composite structures are verified against generic datasheet values; here it was in-scope from the start, because the eventual compliance argument depended on the traceability of every input.
The full seat assembly was modelled in ANSYS APDL: shell elements (SHELL181) for the metal-frame plate structures and the composite laminate, solid elements (SOLID185) for the cast fittings and foam-filled composite domes, beam elements (BEAM188) for the fasteners, and RBE3 constraint elements for load and mass distribution. The assembly was verified against the full UIC 566 load set — extreme longitudinal, lateral and vertical accelerations feeding fastener sizing; operational accelerations feeding weld fatigue against a factor-1.65 allowable derived from the S355 yield; and concentrated loads applied to the seat, backrest, armrest, and folding table. The composite shell was evaluated separately in ANSYS ACP against the Tsai-Wu static failure criterion, with local biaxial reinforcement added at the two locations where the base laminate did not clear the threshold. Sub-models were built for the folding armrest and folding table, each verified against the same standard loads, with contact-based hinge modelling for the armrest stop pins. A modal analysis established the assembly's natural frequencies.
The result is a design package in which every load case, every material property, and every structural decision traces back to either a measured input or a defensible modelling choice — from the styling model through to the manufacturing documentation.
Maximum operational fatigue stress in the steel frame reached 213.3 MPa against an allowable 215.1 MPa. The composite shell's Tsai-Wu utilisation stayed under 1 with the added biaxial reinforcements, peaking at 0.84 at the base. Maximum fastener utilisation was 89% for the M8 grade 8.8 bolts. The aluminium armrest peaked at 149.5 MPa against a 154 MPa yield, and the folding table at 15.4 MPa against 130 MPa.
The concurrent constraint set — full UIC 566 compliance under the mass cap — closed within a single verification cycle.
We needed one partner who could carry the seat from styling model to manufacturing documentation. eCon delivered every layer in-house — mechanical design, material selection, laboratory characterisation, and structural verification.
— Firstname Lastname, [Role], Major European OEM
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