ADHESIVES, GLUES AND SEALANTS


Mechanical properties of adhesives.


Adhesives, as any other material, have a number of characteristics or mechanical properties, which must be known in order to select, design and calculate the adhesive bonding.

Depending on the type of adhesive selected, we will get different mechanical properties to the other adhesives, so we can talk about elastic adhesives when we have a high elongation and rigid adhesive, and when they have a high strength.

The mechanical properties of an adhesive are defined by:

Strength to fracture

We define the strength to fracture of an adhesive as the maximum force per unit area to be implemented in order to destroy the joint.

fracture strength

The strength to fracture is expressed in MPa or N/mm2.

The fracture of the strength is also known as stress to fracture.

Fracture Elongation

We define the elongation to fracture of an adhesive such as displacement or length variation has been the adhesive when it has reached the strength to fracture.

fracture elongation

Modulus of elasticity

The modulus of elasticity is defined as a constant that has the adhesive material that involves both as tension as the elongation, so that if its value is high, the adhesive has high strength but low elongation (rigid behavior) and if its value is small, the adhesive has a high elongation but low fracture strength (elastic behavior).

Depending on the type of stress or load we have under a different elastic modulus for the adhesives ,we work primarily with:

The modulus of elasticity is used in the elastic zone adhesive, compliance the Hooke law.

hooke law

Yield

The yield strength of an adhesive is defined as the maximum tension, stress, load or elongation which allows an adhesive, so that removal of the load once the adhesive completely recovers its original shape.

The elastic limit defines the elastic and plastic behavior of the adhesive.

All values of the mechanical properties of adhesives are obtained by the destructive testing, where the curve represents the stress / strain of the adhesive.

adhesive properties

The curves stress / strain are obtained in the destructive testing of adhesives and hence their mechanical properties vary according to:


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