Fatigue of Plastics

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Fatigue of Plastics

Postby mjb666 » September 23rd, 2018, 5:18 pm

1. Fatigue is the weakening of a material caused by repeatedly applied loads. It is the progressive and localized structural damage that occurs when a material is subjected to cyclic loading. The exposure of plastic materials to dynamic stress can produce several different responses, and will certainly alter the mechanical properties of the material. Fatigue is a very important failure mechanism for plastic components, and a clear understanding of its implications is essential.

OR

2.Image

RESULT

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Re: Fatigue of Plastics

Postby Silversprinter » September 23rd, 2018, 8:14 pm

Which part is that pictured? appears to be on roof light/skylight so if in direct sunlight will become extra brittle over time
even the clips on interior of camper exposed long term will certainly snap!
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Re: Fatigue of Plastics

Postby wonkywheel » September 27th, 2018, 4:19 pm

Mike,
Motorcaravanning.co.uk seem to be doing a good price on Omnivent skylights. The duct tape won't last long in the sunlight either.

Mark
PS
have looked at some of the other threads I take it wing mirrors have taken a back seat ;)
"Success consists of going from failure to failure without loss of enthusiasm" .......(Winston Churchill)

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Re: Fatigue of Plastics

Postby mjb666 » September 27th, 2018, 7:47 pm

Hi Mark

That 'Bodge' is the limit of my abilities, i actually fell off the step ladder climbing up, lucky i fell onto grass. In fact i'm basically useless.

I have had an offer of help from a work colleague to remove the old sky vent and fit a new one. I'm now looking at a direct MPK replacement or the posher MPK Visionstar M Pro c/w with airflow or spending a bit more on either a Fiamma or Dometic/Heki.

I'm really not sure what to do? Price, ease of fittment, style. I quite like the idea of being able to open it right up when it's hot.

I might even replace the larger one above the living area. That's going to fail soon i reckon.

As you are fitting all new items on your build. What have you chosen?

Mike.
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Re: Fatigue of Plastics

Postby wonkywheel » September 27th, 2018, 9:25 pm

Hi Mike,
you must have read my motto, "Success consists of going from failure to failure without loss of enthusiasm" .......(Winston Churchill)

Well, that's me. I'm afraid I tend to work on the theory that if I read the book I can do it. Not as well as some, not as quick as some, and not always right the first time, but, great satisfaction when its nearly right, and I did it. :D
I'm not using all new bits. My original roof vent in "Lightning" (teardrop) was a damaged, Omnivent unit, with a fan. I was going to fit that but a new unused unit came up on ebay, and I managed to win it. So that's going in now. The old unit might move down the camper to the cooking area, at least to start with. The beauty of it is the fan unit. I can buy a new basic vent unit and my old fan will fit in it.


They are quite easy to fit rearly. When the screws are taken out on the inside, the pretty bit falls off and, with a bit of luck, you can ease the outer frame off the mastic and lift it diagonally through the hole. You don't even have to fall off the ladder :roll:
The 400mm square hole is big enough for me to manipulate my way out, so, with something inside to stand on inside you can play tank commanders :lol: , while cleaning the old mastic off.

The fact that the vent inner and outer frames screw together within the 400mm hole and sandwich the roof makes all possible from the inside. Also the basic unit from motorcaravanning.co.uk is about £74 but you can buy the fan assembly later. Unscrew the pretty bit with its screen and blind in it put the fan in then all back togther
simples 8-)

Go on ;) you can do it :geek:

Mark
"Success consists of going from failure to failure without loss of enthusiasm" .......(Winston Churchill)

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