You are my kind of person. Touché! Great story. I worked on F-4's, F15's, A10's and many other aircraft. I left that job and went to SATCOM.. Planes are really dirty. That's not why I cross trained. No future in it.. Today the only plane I would feel safe in is a C130.. My Fav! ----- Original Message ----- From: "Jon Lockwood" <jn_lockwood@xxxxxxxxx> To: <dmcnews@xxxxxxxxxxxxxxx> Sent: Wednesday, February 08, 2012 7:11 AM Subject: Re: [DML] Modified Trailing Arms For 1/2" Bolts > So we some metallurgy people on this site? COOL! > > > ----- Original Message ----- > From: "Martin Gutkowski" <martin@xxxxxxxxxxxxxx> > To: <dmcnews@xxxxxxxxxxxxxxx> > Sent: Wednesday, February 08, 2012 1:53 AM > Subject: Re: [DML] Modified Trailing Arms For 1/2" Bolts > > >> Actually while hard materials tend to be brittle, it's not the same >> thing. Soft is not the same as ductile - eg carbon fibre composite has a >> very high tensile strength and low ductility but is nowhere near as hard >> as even aluminium. >> >> Hardness is a surface property, brittleness (resistance to crack >> propagation) and tensile strength, modulus of elasticity and ductility >> are all structural properties. >> >> Martin >> Sent from my BlackBerry® >> >> -----Original Message----- >> From: "K.L. (KAYO) Ong" <klo@xxxxxxxxx> >> Sender: dmcnews@xxxxxxxxxxxxxxx >> Date: Tue, 07 Feb 2012 16:15:08 >> To: <dmcnews@xxxxxxxxxxxxxxx> >> Reply-To: dmcnews@xxxxxxxxxxxxxxx >> Subject: Re: [DML] Modified Trailing Arms For 1/2" Bolts >> >> Too much hardness (brittle) is just as bad as too soft (ductile)... >> As for Toby's bolts.... So far, Toby's bolt has been serving my car >> very well on the roads and streets of NYC. since his introduction >> many years ago. Before Toby's bolts, I had replace the trailing >> arms bolt twice! First time, they were both bolts were bent upon >> inspection. The right side bolt was more bent to the point a shim or >> two fell out. The second time the right side bolt had actually >> snapped (sheared) off on a right turn!!! I was luck to be one block >> from home... Anyway, my DeLorean was then towed to Rob to have the >> replacement to have Toby's bolt installed... >> >> For what it is worth about softness and hardness about metals from >> the aviation industry.... >> >> Some years ago a helicopter had crashed. Upon inspection, the >> primary rotor blade's pivot securing bolt was at fault. This bolt >> was made in mainland China, where quality control was not a critical >> issue. To the manufacture, steel is steel... The problem was the >> bolt produced was way too soft and did not meet the required Rockwell >> hardness test as prescribed.... The bolt cost was $5.00 US.... It >> was five dollars versus the $20.00 US approved bolt by the >> F.A.A.!!! From that failure there were major lawsuits and I >> believe the Chinese manufacture got away with it, for one, it was >> overseas and government affiliated and two, the company just closed >> shop and change it's name... So, that is about soft metal. >> >> In the USA aviation industry/manufacturing, the rivets that are used >> are sent frozen from the manufactures until they are ready for usage >> upon assembly. If the rivets are removed from the freezer and they >> are not used and or they have been sitting around beyond a designated >> time, they are automatically scrapped. The reason is because the >> room temperature with bring up the molecules movements which raise >> their brittleness (work harden by temperature)... And also, the >> assembler who is pneumatically hammering the rivets must know that >> there are a prescribed amount of "hits" allow to the rivets. This is >> to not to over "work harden" the rivets upon compression which may >> create a condition for premature failure!!! Just several years ago, >> we have seen planes in the news with the fuselage parts ripped off or >> fallen off... Rivet, rivet... That is hardness in metals.... >> >> Kayo Ong >> #5508 >> Lic 9D NY >> >> >> >> On Feb 7, 2012, at 1:53 PM, Matthew wrote: >> >>> http://www.industrialchassisinc.com/Web-blog/?p=622 >>> >>> --- In dmcnews@xxxxxxxxxxxxxxx, "Martin Gutkowski" <martin@...> wrote: >>> > >>> > Tensile strength is only part of the story, you have to be >>> careful with ductility, aka "brittleness" and in general with steel >>> the higher the tensile strength, the more brittle it becomes. A >>> suspension component should have a degree of ductility, but not to >>> the point of fatigue or elastic limit. The torque spec for the TABs >>> is far lower than would normally be applied to such a bolt. >>> > >>> > Martin >>> > >>> > >>> >>> >> >> >> >> [Non-text portions of this message have been removed] >> >> >> >> ------------------------------------ >> >> To address comments privately to the moderating team, please address: >> moderators@xxxxxxxxxxx >> >> For more info on the list, tech articles, cars for sale see >> www.dmcnews.com >> >> To search the archives or view files, log in at >> http://groups.yahoo.com/group/dmcnewsYahoo! Groups Links >> >> >> >> >> >> ------------------------------------ >> >> To address comments privately to the moderating team, please address: >> moderators@xxxxxxxxxxx >> >> For more info on the list, tech articles, cars for sale see >> www.dmcnews.com >> >> To search the archives or view files, log in at >> http://groups.yahoo.com/group/dmcnewsYahoo! 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