thickness of car headlight 2

[abra87]

hello everyone
i m looking to know how to determine the minimum thickness of a car headlight, and if it can't be determined by a mechanical engineering , what low of optics that can help
i m replicating the headlight design and want to know the effect of variable thickness on the light , and if it's accepted or no, in short i need to know how to design a headlight from scratch
thank you

 

[Pud]

Get yourself one from a scrap car. Cut the headlight up and measure the thickness. That is most likely the optimum thickness as determined by (probably) dozens of optical, plastics, and mechanical engineers.
The polycarbonate will also need a coating of some sort to add scratch resistance and prevent yellowing by ultraviolet.

It's a pity the best material is no longer used - glass!


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[IRstuff]

i m looking to know how to determine the minimum thickness of a car headlight, and if it can't be determined by a mechanical engineering , what low of optics that can help

I think it's a bit more complicated than that; I would actually consider buying more that one headlight from said junkyard from cars with different headlight to ground heights and see how they're adapted for their particularly installation location on a car. If you're lazy, then you need to find a car with headlights at the same height as yours. Nowadays, with LED headlights, there might not be any "optics" in the sense of parabolic reflector, since the designers might have decided to use the LEDs' direct emission pattern instead of designing a reflector.

The polycarbonate will also need a coating of some sort to add scratch resistance and prevent yellowing by ultraviolet.

Haven't come across any headlight of mine that prevented the latter ;-)

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[Pud]

IRs: Nor me! Well, not since they were glass.
Not sure what's used today, but traditionally, rear lights were made from acrylic (PMMA), which is UV transparent so unaffected.


Politicians like to panic, they need activity. It is their substitute for achievement.

 

[abra87]

hey, thank you all for you answers, i appreciate it a lot !
i m targeting a specific car model, that its headlight is made with polycarbonate, and yes it needs surface treatment, the headlight of this car model is smooth, no optical features, i ll attach a picture as an example.

i read that the function of this kind of headlights is protecting the inside components,and i read that different transparent materials have different refractive indexes, which will effect the emitted light angle,and i guess it depends on the material thickness.
i m not going to use the same polymer grade, so knowing how they calculated the thickness, considering the resistance against the air pressure and the optical constraints will benefit me.
besides , i believe that there are some transportation regulations or norms that needs to be fulfilled in so the car can be driven legally in the streets, i don't know what are these regulations in what comes to headlights.
thank you all

 

[IRstuff]

Unless you are planning on building the structure with grossly non-parallel surfaces, the optical performance will be close to a flat plane.

The thickness design consideration, I think, are more along the lines of impact/tamper resistance/tolerance

so the car can be driven legally in the streets, i don't know what are these regulations in what comes to headlights.

This is something that you should be able to look up; I hear there's something called "google" that can help you.

https://www.google.com/search?q=hea...aGZIBCDAuMjMuMC4xmAEAoAEBwAEB&sclient=gws-wiz

TTFN (ta ta for now)
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[cowski]

The thickness design consideration, I think, are more along the lines of impact/tamper resistance/tolerance

Also add "manufacturability" to that list. Assuming the part is injection molded, there is a minimum thickness that can be achieved based mostly on the specific material used. The link below shows some common materials and the recommended wall thickness.

https://www.engineeringresourcecenter.com/blog/wall-thickness-guidelines-for-injection-molded-parts

 

[IRstuff]

Also add "manufacturability" to that list.

Sure, I just figured that impact resistance was going to be, by far, the more stringent requirement.

TTFN (ta ta for now)
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[dgallup]

The norms that need to be met will vary by country. In the US headlight lens must be DOT approved.

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