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Joint Pin Reduce Stress Concentration And Improve Bonding Strength
- Oct 23, 2017 -

The actual application of the Joint Pin form can be said to be different shapes, changeable, but the total is composed of the following basic types of individual or combination of each other.

Docking is to two of the adhesive surface gelatinize after the-up, become-body, docking can basically maintain the original shape. Thermoplastic products solvent or hot melt bonding can be used butt, metal and thermosetting plastic products are not suitable for docking, because the butt bearing is uneven pull off force, easy to produce bending and stress concentration, the lateral load is very sensitive to axial tension. At the same time, the adhesion area is small, the bearing capacity is low, the result is not easy to be bad. If you must use docking, you need to wear pins, patches and other reinforcement measures. But for the new design of the structural bonding Joint Pins, it is best to avoid the butt Joint Pin.

Oblique connection is to two by the end of the sticky material to make a certain angle of the slope, gelatinize and then docking, in fact, is less than 90 ° butt. The general oblique angle is not greater than 45 °, and the miter length is not less than 5 times times the thickness of the adhesive. It should be said that the oblique shear force, the distribution is more uniform, the adhesive area increased, longitudinal and transverse bearing capacity is high, and can remain intact, is a better-kind of Joint Pin form. However, in fact, the application is not widespread, because of the difficulties of preparation, if the combination is not good, the thickness of the adhesive layer is difficult to ensure that the expected effect.

Lap is the plate is glued after the glue is laminated in another plate glued to the end of a certain length, because it is a plane bonding, bearing the main shear force, distribution is relatively uniform. Single lap shear Joint Pin is the most commonly used Joint Pin form, with large adhesion area and high bearing capacity, and increases with the increase of lap width. The bearing capacity is not proportional to the lap length, and the bearing capacity of the Joint Pin increases with the increase of lap length in a certain lap length, and is no longer improved when a certain value is reached.

Although the load-carrying capacity of lap Joint Pin is close to-limit value as the thickness of the adhesive increases and the lap length decreases. However, it is difficult to find the lap length directly, usually by experience and test to determine the lap Joint Pin length should not be less than 4 times times the thickness of the adhesive, not greater than 0.5 ~ 1 time times the width.

Generally speaking, the shorter the Joint Pin length, the thicker the adhesive, the thicker the adhesive, the better the toughness of the adhesive, the smaller the rigidity of the adhesive, the smaller the stress concentration. In fact, there is stress concentration in lap Joint Pin, if the end of the adhesive is cut, chamfer, trenching, thinning and so on can reduce stress concentration, improve bonding strength.