SOP for three point bending flexural test
This is a sub-SOP of Generic SOP for Universal Testing Machine Instron 5566A.
Sample requirements:
- Prepare your samples according to ISO 4049 via sectioning, milling, casting, moulding, and etc.
- We strongly suggest following demension for specimens: 2x2x25 mm (for span 20 mm) for polymer based composite, 2x5x25mm (for span 20mm) for ceramics, 1x1x14 (span 10 mm)for some CAD/CAM ceramic materials; 1x4x14 (span 10 mm) for polymer materials
Equipment Preparation:
- Check the power switch of instron and printer
- Check the status of computer, log in as administrator.
- Check the load cell cable is connected and in the proper load range as you need.
- Prepare fixture for your specimens.
Testing:
- Run BlueHill 3 from computer.
- Load your testing method and choose testing filename, save to your own folder. Each group pf specimens can be included in one data file.
- Input speciment information if needed.
- Mount your specimens in the proper fixture. We have two types of fixtures: steel U-shaped support and round black delrin fixture.
- Align the load cell with your specimens. Secure the fixture.
- Set the extension reset before the test. Set the frame safety sensors for upper and lower limit.
- Install proper protection around the fixture and wear safety googoles for yourself.
- Click "start" to test.
- Collect finished specimens fragments and save for further fractograph analysis. Do not match fracture surfaces togather, which will smear off important microstructures.
- Save the results after testing one group specimens. Do not mix different groups of specimens in one data file.
- Print important results when necessary.
Related Standard References:
- ISO/FDIS 4049:2009 Dentistry-Polymer-based filling, luting and restorative materials
- ISO 6872:2008[E] Dentistry -- Ceramic materials
- ISO 178:2012 Plastics -- Determination of flexural properties. the test is stopped when the specimen breaks. Of the specimen does not break, the test is continued as far a possible and the stress at 3.5% (conventional deflection) is reported.
- ASTM D-790-03 Standard Test Methods for Flexural Properties of Unreinforced and Reinforced Plastics and Electrical Insulating Materials. The test is stopped when the specimen reaches 5% deflection or the specimen breaks before 5%.
Reference in Wiki for flexural strength equation and flextural modulus equation . The automatic Young's modulus from Instron doesn't mean anything in three point bend testing. Flextural modulus could be used as modulus of elasticity obtained in flexural mode.