Write a movement history
List each stage from unpacking to end of service: assembly forming, enclosure closure, normal operation, access for repair, and replacement. For each stage, record who or what moves the circuit and whether the path is constrained. Connect the history to installation instructions so a nominally static design is not repeatedly re-creased by an assembly sequence.
Classify a real product's events
| Event | Question to answer | Planning response |
|---|---|---|
| Initial assembly | Is a tool controlling the formed shape? | Document the forming and handling sequence |
| Normal operation | Does the same region repeatedly change shape? | Define movement and representative endurance evidence |
| Service access | Will the flex be unfolded or disconnected? | Specify permitted handling and replacement policy |
| Transport | Can unsupported spans move against the enclosure? | Review restraint and contact points |
Classify regions rather than the whole outline
One assembly can contain a moving loop, fixed routed spans, and reinforced terminals. Name these regions separately and assign their construction and support boundaries. Follow the dynamic design workflow for the moving region, while reviewing terminal loads at its ends. The classification should remain understandable when the circuit is shown flat.
Turn the distinction into acceptance evidence
For an installed circuit, prioritize fit, handling damage, retained shape, and terminal loading after assembly. For repeated movement, define trajectory, rate, environment, electrical monitoring, and the required exposure in a test plan. Mixed duty may require both. Record any service action that invalidates an assumption, such as removing a clamp or opening a normally closed hinge.
Before you release the design
- Count service operations separately from ordinary operating movements.
- Identify the supported and unsupported regions on the flat drawing.
- Record both the normal path and credible assembly misrouting.
- Agree how damaged or previously creased parts are dispositioned.
Watch points
- Static does not mean insensitive to rough handling.
- A product-level cycle count does not describe what every flex region experiences.
Practical questions
Is a circuit that bends only during repair dynamic?
Describe it as an installation or service bend with the expected number and nature of handling events. The useful requirement is the movement history, not forcing every case into one label.
Does choosing dynamic duty determine the material automatically?
No. It establishes a design and test problem. Copper, insulation, construction, geometry, environment, and support still need coordinated selection and verification.
Technical references
References support the material or design context. Check the exact grade, part number, document revision and project conditions before release.Updated 27 September 2026 · Technical content policy · Engineering guidance supports project review; the agreed drawing defines the build.