Tensile strain / safety factors

In summary, tensile strain is the amount of deformation or elongation a material experiences under tensile stress. It is calculated by dividing the change in length by the original length. A safety factor is a ratio that indicates the level of safety in a design, and it is important to consider them to ensure structures and materials can withstand expected stresses. Safety factors are directly related to tensile strain, as a higher safety factor means a material can withstand more strain before failing.
  • #1
giraffasaurusrex
2
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Homework Statement
Hi all.. I would really appreciate any help anyone can give me! I have tried to solve the following and although I understand a) (I think!), I am really unsure between the two possible formulas to use for b), and my answer for c) just seems wrong..! If I am making an obvious mistake I'd love to know..

Thanks in advance!


A load of 50 kN is applied to the tensile member shown in fig. 3. The axis of the rivet is at 30° to the line of action of the load F.

a) calculate the tensile and shear stresses in a 20mm diameter rivet.
b) calculate the tensile strain in a 20mm diameter rivet.
c) if the ultimate tensile stress of the rivet material is 350MPa and it's modulus of elasticity is 150GPa, find the safety factor for the above rivet in operation.
Relevant Equations
Stress=force/area
Strain=Lx/Lo
Elasticity=stress/strain
(Area=πd sq/4)
PXL_20210929_202858757.jpg
 

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  • #2
Your normal and tangential components of force look OK. What is the shear stress and tensile stress in the bolt?
 
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Likes giraffasaurusrex
  • #3
Oh no! Thank you, yes I see the mistake now - I want to say I was focusing on B and C but that would be shameless self promotion (:
This would be the F/A I forgot wouldn't it..? Thank you so much!
 

FAQ: Tensile strain / safety factors

What is tensile strain?

Tensile strain is a measure of the amount of deformation that occurs in an object when it is subjected to tensile stress. It is typically expressed as a percentage of the original length of the object.

How is tensile strain calculated?

Tensile strain is calculated by dividing the change in length of an object by its original length. This is then multiplied by 100 to express it as a percentage. The formula for tensile strain is: ε = (ΔL / L) x 100%, where ε is the strain, ΔL is the change in length, and L is the original length.

What are safety factors in relation to tensile strain?

Safety factors are a measure of how much stronger a material or structure is compared to the expected load or stress it will experience. In the context of tensile strain, safety factors are used to ensure that an object can withstand the expected amount of strain without breaking or failing.

How do safety factors affect the design of structures?

Safety factors play a crucial role in the design of structures, as they help engineers determine the appropriate materials and dimensions to use in order to ensure the safety and stability of the structure. A higher safety factor means that the structure is more resistant to failure, but it also means that more material may be needed, which can increase cost and weight.

What is the recommended safety factor for structures?

The recommended safety factor for structures can vary depending on the type of structure and the materials used. Generally, a safety factor of 2-3 is considered standard for most structures. However, for structures that are subject to high loads or critical applications, a higher safety factor may be necessary.

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