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ASTM Testing Standards

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titleBasic Description:

  • 3-point or 4-point bend test

Figure 3: 3-Point Bend Test

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Figure 4: 4-Point Bend Test

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titleReported during the test:

  • Force versus crosshead displacement, force versus deflection data continuously, or at frequent intervals (around 2-3 recordings per second, with a target minimum of 100 recorded data points)

  • If there are any initial failures, record force, displacement and mode of damage where the failure occurs. 

  • Record mode, area and location of each failure. 

  • Use the failure identification codes, shown in the figure below.

  • Record the max force, failure force, head displacement and the deflection at the moment of ultimate failure. 

  • For ultimate failure modes, record the mode, area and location of ultimate failure for each material. 

  • Calculations:

    • For 3-Point Mid-Span Loading:

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    • For 4-Point, Quarter-point loading:

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    • For 4-Point (Third Point) Loading:

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ASTM D3039_Standard Test Methods for Tensile Properties

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titleReported during test:

  • Failure modes:

    • Record them by giving a code as shown in figure 9, below:


  • There are a few unacceptable failure modes including end-crushing and euler buckling. 

Variable

Symbol

Compressive Stress/ Ultimate Compressive Stress

F cu

Compressive strain/ Ultimate Compression Strain

Ɛi c

Compressive Modulus of Elasticity

E chord

Compressive Poison’s ratio

v c

Transition Strain

μ E

*remember all these formulas will be in the astm document for finding the above values*

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titleTest Specimen Sampling and Geometry:

  • Will conform to the following geometry:

  • At least 20 specimens shall be tested, representing at least four different joints

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titleEquipment and Apparatus:

  • No equipment listed, just apparatus:

    • The machine will have a capacity of no less than 6810kg in compression and shall be fitted with a shearing tool containing a self-aligning seat to ensure uniform lateral distribution of the load.

    • It will be able to maintain a uniform rate of loading so the load may be applied with a continuous motion. The apparatus is pictured below:

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titleProcedure:

  • At least 20 specimens should be tested, they will represent at least four different joints.

  • We will have to prep the test joints:

    • They will be hard maple blocks, having a minimum specific gravity of 0.65 based on oven-dry weight and volume shall be selected. Below is a picture of the test joints and how they should be cut?

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titleBasic Description:

  • I don’t really get how to explain this one to be honest help :CShearing tool/shearing tester.

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titleReported during test:

  • Calculations:

    • Shear stress at failure.

    • Max and min shear stress at failure and percentages of wood failure.

    • The standard deviation of all individual test values.

    • Average shear stress at failure and the average percentage of wood failure.

Variable

Shear Stress at failure

Max and min shear stress at failure and percentages of wood failure

Standard deviation of all individual test values

ASTM D950_Standard Test Method for Impact Strength of Adhesive Bonds

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titleTest Specimen Sampling and Geometry:

  • Use these dimensions if you can:

  • Test 10 test specimens for each adhesive

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