Project Description
SCOPE OF WORK
=============
We are looking for a mechanical engineer to perform a structural Finite
Element Analysis (FEA) on the back frame of an ergonomic office chair,
to validate compliance with BIFMA X5.1 and EN 1335-2 standards BEFORE
tooling release.
This is a CAD FEM analysis V1 with isotropic material assumptions
(knockdown factors will be applied for fiber anisotropy and weld lines).
A separate V2 with Moldflow fiber-orientation coupling will be done
later by another vendor — NOT in scope here.
PART INFORMATION
================
- Office chair back main frame
- Material: PA6 GF30 (Polyamide 6 + 30% glass fiber, datasheet provided)
- Process: plastic injection molding
- Volume: 1,623,579 mm³ — Weight: 2,191 g
- Overall dimensions: ~740 × 482 mm
- CAD will be provided in STEP format after NDA signature
LOAD CASES TO SIMULATE
======================
BIFMA X5.1:
- §5.4 Backrest Strength Functional: 667 N static, 1 minute
- §5.5 Backrest Strength Proof: 1,334 N static, 1 minute
- §5.6 Backrest Durability Cyclic: 400 N × 120,000 cycles
- §5.20 Headrest Strength Test: 333 N applied at the headrest plate
(4 bolts mounting zone)
EN 1335-2:
- §6.2 Backrest static strength: 560 N × 10 cycles
- §6.3 Backrest fatigue: 330 N × 200,000 cycles
ADDITIONAL:
- Asymmetric loading case (user leaning sideways) for torsion check
ACCEPTANCE CRITERIA
===================
- FoS ≥ 2.0 on functional load (yield strength)
- FoS ≥ 1.5 on proof load (ultimate strength)
- FoS ≥ 1.5 on fatigue endurance limit
- Knockdown factors to be applied:
* Anisotropy: × 0.85
* Weld line zones (estimated locations): × 0.5
* Humidity (50% RH): × 0.75
* Temperature 50°C: × 0.85
DELIVERABLES
============
1. Technical report (PDF, English) including:
- Executive summary with GO/NO-GO conclusion
- Methodology (software, element type, mesh size, BCs)
- Mesh visualization and quality stats
- For each load case: Von Mises stress maps, displacement maps,
critical zone identification, local FoS
- Fatigue analysis with S-N curve used
- Compliance summary table per load case and per standard
- Design modification recommendations if needed
2. Native FEM files (Ansys .wbpz, Abaqus .cae, or equivalent)
3. One 1-hour video call to walk through results
REQUIRED QUALIFICATIONS
=======================
- Mechanical engineer with proven FEA experience on injection-molded
plastic parts
- Owns commercial license for at least ONE of: Ansys Mechanical,
Abaqus, NX Nastran, OptiStruct
- Owns CAD software license (SolidWorks, Catia, NX, or Creo) to open
STEP files and perform minor geometry preparation if needed
- Previous experience with glass-fiber reinforced thermoplastics
(PA6/PA66 GF, PBT GF, etc.)
- Knowledge of BIFMA X5.1 and/or EN 1335 standards (or willingness
to study them — to be confirmed)
DESIRED (NOT MANDATORY)
=======================
- Experience in office furniture or seating industry
- Capability for V2 Moldflow→FEM coupling (Digimat / Helius / Converse)
for a possible follow-up project
WHAT TO INCLUDE IN YOUR PROPOSAL
================================
1. Brief CV (1 page) of the engineer who will actually do the work
(NOT just the agency/team profile)
2. List of FEA software licenses you own (with version)
3. List of CAD software licenses you own
4. 2 anonymized examples of similar past projects
(chair / structural plastic / fiber-reinforced part)
5. Proposed methodology (max 1 page): how will you handle the
anisotropy in V1, how will you treat weld line zones, what
element type and mesh size do you plan
6. Detailed quote: base price + price for one additional iteration
7. Lead time from CAD reception to final report
8. Confirmation that you accept signing an NDA before CAD transfer
TIMELINE
========
Target lead time: 3 weeks from CAD transfer to final report
Project start: as soon as proposal is accepted and NDA signed
CONFIDENTIALITY
===============
NDA must be signed before any technical data transfer.
CAD, datasheets, and final report remain the exclusive property of
the client. Confidentiality commitment: 5 years.