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Strength Test Facility for Open Source Appropriate Technology (OSAT) 3D Printing by julianh72 is licensed under the Attribution - Share Alike - Creative Commons license.
© 2011 by julianh72
Instructions
Print one (or more) Test Beds.
Print sufficient identical Test Pieces for the testing program. Keep records of the build and print parameters used (material, used, machine settings, % solid core fill, etc). Weigh the test pieces as a record of overall effective density. Where scales of only limited precision are available, weigh five or more identical pieces in a single weighing to get an effective mean sample weight.
It is suggested that a minimum of three identical test pieces should typically be printed whenever undertaking a formal testing and reporting program, although a single test piece can still yield useful insights into material behaviour when trying to determine a “semi-quantitative” assessment of comparative properties yielded by different printer settings etc. If the set of Test Pieces are printed as a nested suite in a single print run (rather than as a series of sequential print runs), this will ensure all pieces are manufactured under identical conditions, minimising variations due to machine preparation, operator skill, environmental conditions (temperature , humidity, dust), etc. It should be possible to arrange a suite of 5 or even 10 identical test pieces to be produced in a single print run in this way.
Consider printing sets of test pieces in different orientations when it is desired to understand the 3-dimensional orthotropic characteristics of the material.
Install steel pins on test bed, and place test piece on pins
Measure the clearance between the underside of the Test Piece and the Deflection Measuring Pad on the Test Bed
Apply an initial load increment (well below the anticipated failure load) and measure the mid-span deflection
Apply additional load increments and measure the deflection at each increment. It is recommended that data points should be entered into a graphing Spreadsheet or similar as it is recorded, to allow trends to be identified immediately (e.g. possible deflection reading errors, non-linear behaviour may indicate onset of failure, etc)
Repeat for each test piece in a suite, so that statistically meaningful results can be obtained.
Repeat for different manufacturing orientations, so that the influence of orthotropic material properties can be assessed.
