Shear Strength of Reinforced Plastics ASTM D3846

Shear strength of reinforced plastics, per ASTM D3846.

In-Plane Shear Strength of Reinforced Plastics is an important mechanical test used to evaluate the strength of reinforced thermosetting sheet plastics. This test method, ASTM D3846, measures the resistance to compressive forces of a notched specimen with randomly oriented fiber reinforcement, providing valuable data for materials that don't provide reliable data using other methods.

The In-Plane Shear Strength test is designed to measure the strength of materials by applying compressive loads to a notched specimen of uniform width. The test specimens are placed in a fixture and tightened to a specified torque. The sheared area is then measured and used to calculate the Shear Strength of the material.

To conduct the test, the width, thickness, and length between the notches of the specimen are first measured. The specimen is then placed in the fixture and the bolts are tightened to a specified torque. The specimen is loaded to failure at a controlled rate of 1.3 mm/min (0.050 in/min). The sheared area is measured, and the In-Plane Shear Strength is calculated by dividing the maximum shear load by the product of the width of the specimen and the length of the failed area.

The test specimens should have two parallel slots machined into opposite faces, 6.4mm (0.250 in.) apart, and be 12.7mm (0.5 in.) by 79.5mm (3.13 in.) by 2.54 to 6.6mm (0.100 to 0.260 in.) thick. The slots should be deep enough to pass the center point of the laminate, providing a controlled location for loading.

The In-Plane Shear Strength test provides essential data for materials that do not provide accurate results through other methods. The test method can be used to evaluate the effectiveness of randomly oriented fiber reinforcement in thermosetting plastics, which can inform the design and production of a variety of plastic products. The test is widely used in the aerospace, automotive, and consumer goods industries, among others.