[pianotech] FW: [PTG Pianotech]: RE:plate stress- Finite element model

Dale Erwin erwinspiano at aol.com
Mon Apr 30 12:10:52 MDT 2012


Yeah Michael
 This piano-tech lite. Enjoy it while you can


Dale Erwin... RPT
 Mason & Hamlin/Steinway/U.S pianos
www.Erwinspiano.com
209-577-8397

 
  





-----Original Message-----
From: Michael Spreeman <m_spreeman at hotmail.com>
To: pianotech <pianotech at ptg.org>
Sent: Mon, Apr 30, 2012 9:35 am
Subject: [pianotech] FW: [PTG Pianotech]: RE:plate stress- Finite element model






Wayne Stuart thought the weight of his iron frame was excessive.  To quote:  "The detailed finite element model of the existing Stuart and Sons piano frame was built and solved using Strand7. The complex geometry of the piano's cast iron frame was modelled using over 5000 "thin shell" plate elements. The various colours of these elements in the model designate sections of different thickness."  Here's the link which also has the color coded image:   www.strand7.com/html/pianopaper.htm


The new and improved "Stuart Lite" ?



Greg, please let me know if you receive this as I was unable to log in to "my ptg".  I thought perhaps I had forgotten my password, but found out I had not, at least according to  the email confirmation .  I then tried a few different avenues to log in to no avail, so I'm giving up in frustration and posting this here. 





Michael Spreeman 
www.RavenscroftPianos.com





From: noreply at egroups.ptg.org
To: m_spreeman at hotmail.com
Subject: [PTG Pianotech]: RE:plate stress
Date: Sun, 29 Apr 2012 21:39:21 -0400

 
            
                        
    
                                                            
        
        
        
                        
    
	
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                                                        Gregory Graham                                                    
                                                
                                                
                                                    
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                                            It depends on what part of the plate you are looking at.  Some compression, some bending, some torque, some tension, some shear.  Sometimes all in the same place.

 In general, plate stress is equal and opposite the tension of the strings.  The plate struts are mostly under compression, but since they are above the string plane, they are also resisting bowing like an archery bow.  

 Are you looking for the basics, or a more specific discussion?  I'd like to see a digital finite element analysis of plate stress myself, if any of the manufacturers would care to share.  No specific numbers required: just a color coded image showing the stress "hot spots" would be educational.  

 What I've always wondered is why there isn't an iron frame on both sides of the belly for balance.  

 -------------------------------------------
 Greg Graham, RPT (and former Mechanical Engineer)
 Brodheadsville, PA
 -------------------------------------------

 -------------------------------------------
 Original Message:
 Sent: 04-28-2012 07:23
 From: Mark Ritchie
 Subject: plate stress


 When string tension is applied to the piano in what direction is the stress on the plate?

 -------------------------------------------
 M.Ritchie
 -------------------------------------------




                                        
                                    
                                
                            
                            
                            

                            
                                
                                                                        
                                        
                                                                                    

                                    
                                    
                                        
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