This sounds like designing fenders for ships. The ship has velocity energy which is converted into elastic energy in the fender.
Bob Garner
From: Casey K. Hemmatyar [mailto:khemmatyar@gmail.com]
Sent: Friday, May 23, 2008 11:27 AM
To:
Subject: RE: Was embedded timber post (80 Tons trailer impact on Structure)
Bill:
You're right the ft*kips is an Energy unit. However the unit I've indicated is ft-kips (not ft*kips) and it is Force unit.
Regards
Casey K. Hemmatyar, SE
-----Original Message-----
From: William Haynes [mailto:gtg740p@gmail.com]
Sent: Friday, May 23, 2008 11:07 AM
To: seaint@seaint.org
Subject: Re: Was embedded timber post (80 Tons trailer impact on Structure)
Energy or work has units of ft*kips, not force. The force required to
stop a vehicle also depends on the internal response of the vehicle
during the impact.
On Fri, May 23, 2008 at 1:41 PM, Casey K. Hemmatyar
<khemmatyar@gmail.com> wrote:
> Great David;
>
> Just to refresh your memory, it has a 28,340 k-ft of Force but not Energy.
>
> Applying Work-Kinetic Energy Theorem:
>
> Wnet = Kf – Ki= ½*mv^2
>
> W [Work]= ½*mv^2
>
> m=mass; kg
>
> v= Speed; meter/sec
>
> W=(½) (80*1016)*(70*1.609*1000/3600)^2=39,779,275 Joules (This is "Work")
>
>
>
> 1 Joule≈0.73756 ft-lb
>
> F [Force]=39,779,275*0.73756/1000=29,340 ft-k
>
>
>
> Regards
>
> Casey K. Hemmatyar, SE
>
> ___________________________________________________________
>
> From: David Topete [mailto:d.topete73@gmail.com]
> Sent: Friday, May 23, 2008 8:59 AM
> To: SEAINT
> Subject: Was embedded timber post
>
>
>
> http://news.enquirer.com/apps/pbcs.dll/article?AID=/20080521/NEWS01/805210387
>
>
>
> If my calcs are correct, an 80-ton trailer at 70 mph creates 26,200 ft-kips
> of energy. (F = 1/2 mv^2 if my math serves me correctly... ) That is about
> 10k at 30". Or am i way off?
>
> --
> David Topete, SE