Category: Sandwich Core

ASTM D1781

September 22, 2020

Standard Test Method for Climbing Drum Peel for Adhesives

Scope:
This test method covers the evaluation of the peel strength necessary to de-bond the flexible adherend from a rigid substrate.

Procedure:
The specimen is prepared either by a skilled technician onsite or by the manufacturer prior to delivery.  The climbing drum peel fixture is inserted into the universal testing machine and then a calibration test is performed to determine the torque necessary to bend the flexible adherend around the fixture. After the calibration torque value is inserted into the software calculations, a specimen is placed in the fixture and the dimensional and material criteria are entered into the software.  After testing, the client may require detailed photographs of the specimen to analyze the adhesive or cohesive failure modes.  Multiple tests will be performed to determine variability.

Data:
Maximum and minimum load, average peel strength, and average peel torque.

Equipment used
Test frame, climbing drum peel test fixture, test method software.

ASTM C393

September 22, 2020

Standard Test Method for Core Shear Properties of Sandwich Constructions by Beam Flexure

Scope:
This test is for the determination of the compressive strength and modulus of sandwich core materials.

Procedure:
After conditioning and machining the specimen to appropriate specifications, the specimen is centered on the lower platen.  Proper centering is crucial to achieve uniform loading.  Preloading is required before proceeding with the test.

Data:
Ultimate flatwise compressive strength, ultimate force prior to failure.

Equipment Used:
Loading platens, Instron test frame.

ASTM C365

September 22, 2020

Standard Test Method for Flatwise Compressive Properties of Sandwich Cores

Scope:
This test is for the determination of the compressive strength and modulus of sandwich core materials.

Procedure:
After conditioning and machining the specimen to appropriate specifications, the specimen is centered on the lower platen.  Proper centering is crucial to achieve uniform loading.  Preloading is required before proceeding with the test to ensure immediate load ramp during strain.

Data:
Compressive strength, strain, and modulus of elasticity.

Equipment Used:
Loading platens, Test frame.

ASTM C364

September 22, 2020

Standard Test Method for Edgewise Compressive Strength of Sandwich Constructions

Scope:

This test evaluates the compressive properties of structural sandwich construction in a direction parallel to the sandwich facing plane.  Allowable core materials include those with continuous bonding surfaces, as well as discontinuing bond surfaces such as the honeycomb pattern.

Procedure:

After conditioning and machining specimen according to the standard, place the specimen in the edge clamping fixtures as required.  The speed of testing is set to ensure the specimen fails within three to six minutes and a compressive is applied until rupture at this rate.  If axial strain is required, at least two strain gauges are to be used, otherwise, only force per deflection are recorded.  Record the location and mode of failure for each specimen.

Data:
Ultimate edgewise compressive strength, ultimate force prior to failure, compressive strain, and final geometry.

Equipment used:
Test frame, sandwich panel edgewise compression test fixture, two or more strain gauges, test method software.

ASTM C297

September 22, 2020

Standard Test Method for Flatwise Tensile Strength of Sandwich Constructions

Scope:
This test is designed to test for bonding stability, load transfer, and flatwise tensile strength of sandwich core material. This test is applicable to continuously bonded surfaces or discontinuous surfaces such as a honeycomb material.

Procedure:
The specimen is prepared by bonding both faces to metallic blocks that can be fit to the tension fixtures by means of a pin, thus creating a universal joint.  The blocks are then pulled apart at the testing speed designated in the standard until rupture while.

Data:
Tensile strength and strain, modulus of elasticity, failure location, and failure mode.

Equipment Used:
Test frame, aluminum blocks and fixtures.

ASTM C273

September 22, 2020

Standard Test Method for Shear Properties of Sandwich Core Materials

Scope:
This standard covers the evaluation of the shear properties of sandwich core materials.  It determines the shear strength in the plane parallel to the facing, and the shear modulus associated with the strains in the plane normal to the face.  Core material forms include those with continuous bonding surfaces such as balsa wood and foams, as well as discontinuous bonding surfaces such as those containing a honeycomb structure.

Procedure:
After conditioning and machining the specimen according to the appropriate ASTM standard, the specimen will be adhered to shear plates. Dimensional and material criteria is then enter into the software, the shear plates and specimen are attached to hinged fixtures and inserted into the test machine. Perform the test multiple times to evaluate variability.

Data:
Individual core shear modulus, ultimate shear strengths, 2% offset core shear strengths, failure mode, and location of failure.

Equipment used:
Test frame, sandwich panel shear test fixture, test method software.

ASTM C271

September 22, 2020

Standard Test Method for Density of Sandwich Core Materials

Scope:
This test is for determining the density of a sandwich cored materials.

Procedure:
The specimen is first conditioned to the proper specifications, then is measured and weighed so as to characterize its density.

Data:
Density.

Equipment Used:
Dial caliper or micrometer, digital mass balance.