ADVANCED MATERIALS & PROCESSES | OCTOBER 2023 38 Product Specifications and Verification, dealing with the process for design implementation, geometrical product specification, graphical representation of engineering drawings and 3D modeling, and technical documentation. In September 2022, TPR/1/8 Technical Product Realization—BS 8888 Technical Product Specification committee established a technical sub-committee TPR/1/8/1 for the “design of graphical symbols for use in the technical documentation of products—4D printed parts— shape transformations” to undertake this work. USE CASE The framework for this technical product documentation is based on three concepts. These are illustrated in the use case of a generic mini-gripper shown in Fig. 1. First, the shape state (S<num>) expresses the functionally critical features FEATURE 6 Fig. 2 — Shape states S1, S3, and S4 share a common datum reference frame (DRF) as defined in S2 under reference conditions to ISO 1. of the part in each of its shape transformations using the geometrical product specification (GPS) language (Fig. 2). The mini gripper’s four functions are: to constrict a flexible tube, remain idle in a NO (normally open) position, hold and position a rigid rod, and to constrict and hold at the same time, giving four shape states. The allowable deviation in dimensional size and tolerance in geometric form of the functionally critical features on the part for each shape state may be expressed by directly annotating the features on the Fig. 3 — Transformation control frame. Shape State S1 Function: Constrict a flexible tube Shape State S3 Function: Hold and locate a rigid rod Shape State S2 Function: Idle under reference ISO 1 Shape State S4 Function: Constrict a flexible tube AND hold and locate a rigid rod
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