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V1 of the Universal Testing Machine
Welcome to the Wiki for the open source "UTM" (Universal Testing Machine) developed by Materiom and the University of Sheffield.
This instrument is designed to be built with modest mechanical / electrical knowledge and tooling access, whilst being a highly capable instrument.
Please see the overview below for an appreciation of the instrument, the design rationale and the instrument capabilities.
Note that at the current time of writing, this is a V1 instrument. The instrument design is subject to improvement. Whilst a functioning instrument can be built with the information outlined here, this Wiki details recommended alterations for a V2 instrument.
Prior to considering build of an instrument, the wiki should be reviewed to fully familiarise yourself with both the requirements of building an instrument, and the recommended alterations at the current stage of development.
1. 1. Overview: instrument features and design rationale
2. 1. Mechanical: instrument layout overview (and high level design notes)
2. 2. Mechanical: online CAD file organisation
2. 3. Mechanical: bill of materials and ordering parts
2. 4. Mechanical: basic part preparation and cutting lists
2. 5. Mechanical: advanced part preparation (including videos)
2. 6. Mechanical: step by step build of instrument feet and aluminium frame
2. 7. Mechanical: step by step build of instrument superstructure
2. 8. Mechanical: step by step build of instrument moving parts
2.10. Mechanical: light source and camera mounts
2.11. Mechanical: instrument door cover design notes and related parts
2.12. Mechanical: electronics mounting notes and related prototype parts
2.13. Mechanical: notes for future instrument revisions and potential future accessories
2.14. Mechanical: design specific commercial parts and interdependencies
2.15. Mechanical: FEA analysis notes
3. 2. Electronics: online CAD file organisation and further design notes
3. 3. Electronics: bill of materials and ordering parts
3. 4. Electronics: assembly (overview guide)
3. 5. Electronics: verification and setup
The Universal Testing machine is designed to test mechanical properties of materials, but is analogously capable of causing damage and/or injury to objects or people if not used as intended. Elements of the mechanical and electronics build include hazards such as the use of machine tools and soldering irons which this guide assumes the user to be competent with from a safety perspective, and that the user will seek advice and guidance from suitable sources when required. Use of safety glasses is strongly recommended when operating the instrument re brittle failure of samples. Furthermore, this is not a commercial instrument and, and whilst features such as interlocks, emergency stop and operator guards have been designed, implemented, and/or suggestions made for future instrument revision, the designs are presented as is. The authors/contributors accept no liability for any injury, loss or damage resulting from either building or operating this instrument.
One key hazard area is electrically associated hazards. The instrument is powered via a off-the shelf low voltage "trailing" power supply, mitigating the requirement to work with mains electricity directly, and the instrument itself does not contain/generate any high voltage sources. This power supply should be PAT tested / safety inspected before use and at regular intervals. The risk of fire from faulty / short circuited instrument electronics is abated by a liberal use of fuses and inherent over-current protection in the trailing power supply, however final responsibility falls with the person building the instrument and the user to have sufficient knowledge/attentiveness to safely build and operate the instrument. Some electronics will generate heat in use, but should not be sufficient to present burn hazards.
A second key area is entrapment/crush injuries. Whilst the instrument moves slowly, the high forces the instrument can develop presents a hazard. The use of the suggested guards and interlocks is strongly recommended (for this as well as flying pieces of samples), as well as use of the emergency stop button to isolate the instrument prior to moving mechanical parts or exchanging samples. Obvious precautions such as keeping fingers and clothing away from the instrument whilst in motion should be observed.
Note that it is also possible to cause damage to the instrument, in particular from foreign objects in/dropped into the instrument, or clashes between the instrument static and moving parts, which are noted later in this Wiki (e.g. Step 2. 9. 3. 5). Improper calibration / operation of load cells, particularly on compression tests, also has the potential to subject the instrument to excessive force levels and cause damage. Aspects of instrument operation also require particular user attention to detail, specifically when interchanging gas springs between a compression and tensile test.