1. Poliamid (Nylon) Tensile Strength vs Yield Strength 2.Tensile Stress vs Tensile Strength

Question

I am looking for mechanical properties of Poliamid PA66 and PA6.

1. Which characteristics should be used to calculate poliamid bolts endurance? On some websites (of poliamid products), only Tensile Strength is given, on others only Yield Strength.

This website seems helpful - all properties are listed For PA66: http://catalog.ides.com/Datasheet.aspx?I=26793&E=217089 For PA6: http://catalog.ides.com/Datasheet.aspx?I=26793&E=217088

However, I got confused and don't get the difference between them.

2. What is the difference between: a. Tensile Strength (Yield, 23°C) b. Tensile Stress (Yield, 23°C) c. Tensile Stress (Break, 23°C) d. Tensile Strain (Yield, 23°C) ?

3. Why the value of Tensile Stress (Break, 23°C) is lower than Tensile Stress (Yield, 23°C)?

Thank you for help. :)

Answer 1

I finally managed to find some answers. I will write it in case sb need it in the future.

There is a standard for this! ISO 527-1, 1993. It has great chart included (stress-strain). Stress-strain curves can be very different for different plastics (with yield point or without).

tensile strength - is a max tensile stress sustained by the testes specimen during the test.

tensile stress at break - tensile stress when specimen ruptures

tensile stress at yield - tensile stress when there is increase in tensile strain without increase in tensile stress.

Tensile stress at break can be smaller that tensile stress at yield. Therefore, for my bolt calculation I will go with tensile strength value (maximum).

Therefore, the question is closed I think.