ASTM D3518_Standard Test Method for In-Plane Shear Response of Polymer Matrix Composite Materials by Tensile Test

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Last updated: Feb 08, 2021 by Tommy Tran
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The following summary is from the ASTM document D3518/D3518M.

 

The following symbols should be known along with these two diagrams:

 

 

 

The meaning of the test:

  • The purpose is to produce in-plane shear property data

  • The following factors will influence the shear response and should therefore be reported:

    • material

    • methods of material prep and lay-up

    • specimen

    • stacking sequence

    • overall thickness

    • specimen prep

    • specimen conditioning

    • environment of testing

    • specimen alignment and gripping

    • speed of testing

    • time at temperature

    • void content

    • volume percent reinforcement

  • The following properties will be derived during this test:

    • In-lane shear stress versus shear strain response

    • In-plane shear chord modulus of elasticity

    • Offset shear properties

    • Max in-plane shear stress for +/- 45o laminate

    • Max in-plane engineering shear strain for a +/- 45o laminate

 

Equipment required:

Refer to: ASTM D3039_Standard Test Methods for Tensile Properties

 

The only difference is that this method requires that the force-normal strain data will be measured in both the longitudinal and transverse directions of the coupon.

Geometry:

Refer to: ASTM D3039_Standard Test Methods for Tensile Properties

 

Along with these geometries, you must also:

  • modify the stacking sequence so it will be [45/-45]ns, where 4 </- 5 for unidirectional tape (16, 20, or 24 plies) and 2</- n </- 4 for woven fabric (8, 12, or 16 plies).

  • The coupon has a recommended width of 25mm [1.0 in.], and the recommended coupon length range is 200 to 300mm [8 to 12 in.]

  • Tabs are not required for this test

 

Specimen Preparation:

Refer to: ASTM D3039_Standard Test Methods for Tensile Properties

 

 

Procedure:

Refer to: ASTM D3039_Standard Test Methods for Tensile Properties

 

Along with the above procedure, this test will have normal strain instrumentation in both the longitudinal and transverse directions. It will also have continuous or nearly continuous force-normal strain data recording. Also, note that if ultimate failure doesn’t occur within 5% engineering shear strain, the data will be truncated to the 5% engineering shear strain mark. Once truncated, the 5% engineering shear strain will become the maximum shear stress. Any truncation must be noted in the report. The following are some typical shear stress-engineering shear strain plots:

The following are some calculations that shall be done during the test