Freestyle suspension issues

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Beagler
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Elongation at break is the measure of a test specimen’s initial length divided by its length right before fracturing in a tensile test, multiplied by 100 to give a percentage. A large elongation at break suggests the material “stretches” more; in other words, it is more prone to increased ductile behavior before fracturing. Titanium is such a material, where it stretches almost half its length before fracturing. This is yet another reason why titanium is so difficult to machine, as it pulls and deforms instead of chips off. Steel comes in many varieties but generally has a low elongation at break, making it harder and more prone to brittle fracture under tension.

2019 310S 1.6 Sigma

aerobod
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Shear strength of a 12.9 steel bolt is nominally 720MPa, compared with 550MPa for a titanium bolt. Also a 12.9 bolt has a fatigue strength at 10E7 cycles of around 350MPa compared with 240MPa for a titanium bolt. The yield point of a 12.9 bolt is 1100MPa, above the 950MPa UTS of a titanium bolt.

Except for corrosion resistance and weight, a 12.9 steel bolt will outperform a titanium bolt at any given load.

James

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I think the answer to this problem was in post #3

 

 

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Beagler
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Ultimate Tensile Strength

Ultimate tensile strength of low-carbon steel is between 400 – 550 MPa.

Ultimate tensile strength of ultra-high-carbon steel is 1100 MPa.

Ultimate tensile strength of Ti-6Al-4V – Grade 5 titanium alloy is about 1170 MPa.

 

The correct steel bolt designed for this application correctly torqued should be sufficient.

2019 310S 1.6 Sigma

aerobod
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Yes the correct length of 12.9 bolt would be the most appropriate here, key that the trimmed length to give a clean shank through the rose joint is used.

UTS of 12.9 bolts is 1200MPa (as indicated by the "12" in 12.9; these are alloy steel bolts, as opposed to plain carbon steel), but fatigue strength is definitely a factor, Titanium is generally not as good as steel in that respect as a % of UTS for a given number of cycles, although much better than aluminium.

James

Beagler
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CPG Charlie,

What spec does the original design/ part number of the bolt call for. 

2019 310S 1.6 Sigma

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Your clearly not familair with the application Beagler....... 

 

Beagler
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Is this not it.

https://caterhamparts.co.uk/watts-linkage/4897-watts-linkage-kit-metric-chassis-de-dion.html

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No

Beagler
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Is it a Caterham produced system and for road or track use.

 

2019 310S 1.6 Sigma