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<blockquote data-quote="FoxPro5" data-source="post: 4383617" data-attributes="member: 562649">//content.invisioncic.com/y282845/emoticons/tongue.gif.6130eb82179565f6db8d26d6001dcd24.gif How come whenever you read what Degenics says you feel super unintelligent?You need to add cross-bracing to the roof to prevent it from flexing.Your deadening mats that contain a layer of foil (CLD) on butlyene rubber convert mechanical energy to heat. The math equations used to model this type of damping (called hysteretic structural damping) don&#039;t factor in weight. Therefore, most of this &quot;mass loading&quot; you read about on forums is just incomplete, limited thinking at best.CLD works better on stiffer structures to begin with or situations were shear force along the substrate is high. A flexing roof is one of those situations, partly. It&#039;s also a situation where the metal flexes back and forth...or pulsates. In this case, it&#039;s better to use an extensional damper (ED) like a liquid, as it has a better ability to counter flexing deformation stress.A good solution would be CLD + ED plus additional cross-bracing perpendicular to the lines of shear, particularly in the center of the roof where the summation is the highest.A good analogy that sort of disqualifies this &quot;mass loading&quot; business would be the resonant action of an undamped snare drum.</blockquote>

[QUOTE="FoxPro5, post: 4383617, member: 562649"] [IMG]//content.invisioncic.com/y282845/emoticons/tongue.gif.6130eb82179565f6db8d26d6001dcd24.gif[/IMG] How come whenever you read what Degenics says you feel super unintelligent? You need to add cross-bracing to the roof to prevent it from flexing. Your deadening mats that contain a layer of foil (CLD) on butlyene rubber convert mechanical energy to heat. The math equations used to model this type of damping (called hysteretic structural damping) don't factor in weight. Therefore, most of this "mass loading" you read about on forums is just incomplete, limited thinking at best. CLD works better on stiffer structures to begin with or situations were shear force along the substrate is high. A flexing roof is one of those situations, partly. It's also a situation where the metal flexes back and forth...or pulsates. In this case, it's better to use an extensional damper (ED) like a liquid, as it has a better ability to counter flexing deformation stress. A good solution would be CLD + ED plus additional cross-bracing perpendicular to the lines of shear, particularly in the center of the roof where the summation is the highest. A good analogy that sort of disqualifies this "mass loading" business would be the resonant action of an undamped snare drum. [/QUOTE]

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