What is stress-strain curve of polymer?
Stress-strain curves show the response of a material to an applied (usually tensile) stress. They allow important information such as a material’s elastic modulus and yield stress to be determined. Accurate knowledge of these parameters is paramount in engineering design.
Do polymers have linear stress-strain curve?
The blue curve is a plastic polymer and is similar to curves for many metals. Its behavior begins in the linear elastic deformation region. As the curve transitions from the elastic to plastic deformation typically there is a peak stress. For polymer materials, this peak stress is identified as the yield stress.
What is the relationship between stress and strain curve?
Hooke’s law explains the relationship between stress and strain. According to Hooke’s law, the strain in a solid is proportional to the applied stress and this should be within the elastic limit of that solid.
Do polymers have strain hardening?
For some polymers, strong stretching with a stress minimum and break at a much higher stress is observed. This phenomenon is known as “strain hardening” and “stress induced crystallization”.
Why is the strain stress curve important?
The stress-strain curve provides design engineers with a long list of important parameters needed for application design. A stress-strain graph gives us many mechanical properties such as strength, toughness, elasticity, yield point, strain energy, resilience, and elongation during load. It also helps in fabrication.
How does strain rate Affect polymers?
Increasing strain rate has the effect of increasing both the modulus and the yield stress and flow stress of a polymer.
Do polymers have yield strength?
The yield strength of the plastic polymer is the corresponding stress where the elastic region (linear portion of the curve) ends (Fig. A1. 14). The tensile strength is the stress corresponding to the fracture of the polymer.
What stress-strain curve tells us?
Stress strain curves visually display the material’s deformation in response to a tensile, compressive, or torsional load. Depending on the material being tested, a stress strain curve can indicate key properties of the material including its elastic region, plastic region, yield point, and ultimate tensile strength.
Do polymers strain harden more than metals?
In general, polymers strain harden more than metals.
Why stress-strain curve is important?
What is stress and strain with example?
For example, a stress on a rubber band produces larger strain (deformation) than the same stress on a steel band of the same dimensions because the elastic modulus for rubber is two orders of magnitude smaller than the elastic modulus for steel.
Which material is stronger stress-strain curve?
Variables in the stress-strain curve The slope angle of this straight line can be used to deduce how stiff the material is. The steeper this line rises the stiffer the material. If the graph is shallower, the material is elastic. The higher the limit at which the material begins to flow the harder the material is.
What affects the strength of polymers?
The physical properties (such as transition temperature, viscosity, etc.) and mechan- ical properties (such as strength, stiffness, and toughness) depend on the molecular weight of polymer. The lower the molecular weight, lower the transition temperature, viscosity, and the mechanical properties.
Which polymer has the highest tensile strength?
PAI – Polyamideimide
PAI – Polyamideimide (PAI) boasts the highest tensile strength of any plastic at 21,000 psi. This high performance plastic has the highest strength of any unreinforced thermoplastic, good wear and radiation resistance, inherently low flammability and smoke emission, and high thermal stability.
Which comes first stress or strain?
Stress strain curve is a behavior of material when it is subjected to load and frm SN curve we can say stress generates only when there is deformation (or it is about to deform) caused by some mechanical or physical forces. Therefore Strain always comes first then only stress generates.
Does strain hardening increase yield strength?
Strain hardening is one of the most commonly used means of adding strength to an alloy. It is simply the use of permanent deformation to increase the strength of the metal. Other names for strain hardening are cold work and work hardening.
What are the differences in deformation between metals and polymers?
However, a real metal undergoes strain hardening, which tends to increase the load-carrying capacity of the specimen as deformation occurs. As opposed to alignment of molecules in polymers, deformation in metals takes place due to the movement of dislocations.