Return-Path: Sender: (Marvin Kaye) To: lml@lancaironline.net Date: Sat, 03 Apr 2004 22:40:54 -0500 Message-ID: X-Original-Return-Path: Received: from imo-m27.mx.aol.com ([64.12.137.8] verified) by logan.com (CommuniGate Pro SMTP 4.2b1) with ESMTP id 3144557 for lml@lancaironline.net; Sat, 03 Apr 2004 22:31:21 -0500 Received: from Newlan2dl@aol.com by imo-m27.mx.aol.com (mail_out_v37_r1.2.) id q.164.2dad3d37 (3940) for ; Sat, 3 Apr 2004 22:31:12 -0500 (EST) From: Newlan2dl@aol.com X-Original-Message-ID: <164.2dad3d37.2da0db80@aol.com> X-Original-Date: Sat, 3 Apr 2004 22:31:12 EST Subject: Re: [LML] Re: mixing carbon and e-glass X-Original-To: lml@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="-----------------------------1081049472" X-Mailer: 9.0 for Windows sub 5017 -------------------------------1081049472 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit I would argue that the foam is used inplace of honeycomb for puncture resistance. Try taking a sharp object and stick it into foam and there isn't a huge difference. What would be better is balsa core for impacts such as rocks, high heels and tools being dropped. Ironically, this may be worse for the structure since balsa is so strong in compression, it will "telegraph" an impact to the far side whereas foam and honeycomb doesn't. A hammer blow to a blasa maniate can be seen on the backside where the round detail of the head of the hammer is outlined. Un-crosslinked PVC core (Airex) is even better at protecting laminates than crosslinked PVC (Divinycell and Klegecell) since it is more flexible and almost impossible to destroy by impact. It unfortunately will creep under sustained laod and gets soft when heated so it's unsuitable for thin skinned structures. We did a composite analysis for Randy Smythe, an Olympic Gold medal winner, awhile back for his 20' day sailing catamaran to race in the Worrell 1000 (1000 miles of open ocean sailing from Virginia beach to Florida in 5 or 6 stops). Unfortunately, the Divinycell core we spec'd was substituted with Airex somewhere along the way. Around the second or third day, the leeward hull collapsed at a crossbeam due to sustained load causing the inside of the hull core at that point to copress, becomign thinner, causing a reduction in the section modulus and ultimately collapsing. So EVERYTHING comes at a price! Dan -------------------------------1081049472 Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable

I would argue that the foam is used inplace of honeycomb for puncture r= esistance. Try taking a sharp object and stick it into foam and there=20= isn't a huge difference. What would be better is balsa core for impact= s such as rocks, high heels and tools being dropped. Ironically, this=20= may be worse for the structure since balsa is so strong in compression, it w= ill "telegraph" an impact to the far side whereas foam and honeycomb doesn't= . A hammer blow to a blasa maniate can be seen on the backside where t= he round detail of the head of the hammer is outlined. Un-crosslinked=20= PVC core (Airex) is even better at protecting laminates than crosslinked PVC= (Divinycell and Klegecell) since it is more flexible and almost impossible=20= to destroy by impact. It unfortunately will creep under sustained laod= and gets soft when heated so it's unsuitable for thin skinned structures.

We did a composite analysis for Randy Smythe, an Olympic Gold medal win= ner, awhile back for his 20' day sailing catamaran to race in the Worrell 10= 00 (1000 miles of open ocean sailing from Virginia beach to Florida in 5 or=20= 6 stops). Unfortunately, the Divinycell core we spec'd was substituted= with Airex somewhere along the way. Around the second or third day, t= he leeward hull collapsed at a crossbeam due to sustained load causing the i= nside of the hull core at that point to copress, becomign thinner, causing a= reduction in the section modulus and ultimately collapsing. So E= VERYTHING comes at a price!

Dan

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