How to judge whether tempered glass is artificially damaged or naturally cracked?

How to judge whether tempered glass is artificially damaged or naturally cracked？ Man-made damage:Individual owners are broken during the interior decoration due to improper operation protection.Some open fans forget to close,and are instantly colosed in strong winds,causing damage. 2.Glass self-explosion:part of the tempered glass is the glass self-explosion caused by the presence of nickel sulfide in the original glass 3.Thermal cracking:Some glass breaks at the edge or corner position.Some of the glass is obviously installed during construction due to the installation stress of the glass due to the bolck,isolation and other protection,and the glass is excited under the solar heat. Thermal stress concentration causes damage. 4.Product processing defects:Individual glass is a small defect such as edge micro-cracks during the production process.Under the sun exposure,the micro-cracks expand beyond the glass's own stress limit and eventually break.

The definition of self-explosion of tempered glass:tempered glass directly acts on the glass without external force,and the glass itself automatically cracks.The natural phenomenon of  fracture,such as the determination of"self-explosion of tempered glass"must meet the follo-wing characteristics:

1)There is a butterfly-shaped tipping point,and dark stone points can be observed at the interface of explosion point.

2)The explosion point is no longer the edge and corner of the glass 

3)No point of impact on the explosion point.

The reason for self-explosion:the expansion of nichkl sulfide inside the tempered glass is the main cause of self-explosion of tempered glass.Since the glass is subjected to tempering tre -atment,compressive stress is formed on the surface layer of the glass,and tensile stress is fo -rmed in the inner core layer,and the compressive stress and the tensile stress together form a balanced lift.However,the glass material is highly brittle and has a strong pressure-resistan -t type,but the tensile property is very weak.Therefore,most of the glass breakage is caused  by a change in tensile stress.When the nichel sulfide crystal in the tempered glass undergoe -s a phase change,its volume expands to cause a larger tensile stress inside the tempered gl -ass,and the tensile stress is greater than the compressive stress.When the tensile stress exce -eds the limit of the glass itself,the pressure the stress and tensile stress will destroy the bala -nce body,which will lead to the self-explosion of the tempered glass.