The 3-point bend test will provide information on the flexural strength of your sample and can accurately provide Young's modulus and tensile strength of a material.

Dear Rakesh,

Let’s go to find together an intuitive answer, going from the requirements of your application!

Function of the type of solicitation, in many cases for engineering parts is required a high tensile strength, enhanced rigidity under stress, good impact resistance, etc.

The flexural testing will give information about the ability of the material to resist to the deformation under load. If the PLA items are mechanically solicited to a beam loading, the flexural test (as the three-point flexural test) will give information about the maximum stress and strain of material just before it yields, but also other information of interest (e.g. flexural modulus). See more information in the specific standards (Flexural Test of Plastics ASTM D790, ISO 178).

Please consider also that you can compare PLA (without coating) to PLA (316L stainless steel coated), to have information about beneficial (or detrimental) effects of the coating, about the aspect of the surface after testing, etc., but I will refrain more comments.

Good luck in your R&D work and best regards,

Marius

Depending on the aspect ratio of your specimen, it can be used to measure either shear strength or tensile or compressive strength of the material depending on the failure modes.

The main point to see the 3 points bending is to obtain flexural stiffness of the beam, finding out the distribution of the stress on the cross-section, and studying the effect of stress concentration on the beam due to 3 points bending compared to the 4 points bending test.

Please see these papers:

Article Mechanical behavior of thick composite tubes under four-point bending

Article Structural analysis of composite tubes using a meshless anal...

Thanks