Question

Compare the maximum normal stress you calculated in question 5 with the typical tensile and compressive strengths of mortar in Table 4. Comment on the expected failure mechanism for the 4-point bending test. Compare the expected failure mechanism with the actual failure or deformation of the sample you observed in the video (5%).

The maximum normal stress calculated in question 5 I got was 3.32MPa. Can you use it to compare to the values of tensile strength and compressive strength

Table 2: Typical strength values Material PVC 52 72

Tensile strength = 3MPa and Compressive strength = 45MPa

Answer 1

The expected failure modes observed during four-point bending of sandwich panels: a) core shear failure under the loader, b) face wrinkling and face/core debonding, c) slippage of the bottom face, d) cracking around the fastener, e) initial face/core debonding, f) core tensile failure in the mid-plane of the specimen and core shear failure under the loader for specimen.

No actual failure mode given for comparison.

The maximum normal stress in concrete is higher than the tensile strength of the concrete that means the characteristic compressive strength of the concrete needs to be increased i.e a concrete of higher grade should be used.