Description / Abstract: Material Description. The material defined by this specification is a laminated vibration damping steel patch (LVDSP) blank consisting of either two (2) similar or dissimilar metal sheets of the same or different thickness separated by, and bonded by, a viscoelastic core. The patch blanks shall be applied on interior surfaces, however exposure to corrosive environments may exist at pierced/trimmed hole locations. The engineering drawing will specify dimensions, tolerances, sheet steels, and coatings required. Only unexposed (U) applications have been approved for LVDSP applications. LVDSP will have approximately the same density as homogenous or monolithic steel sheets. The elastic modulus, however is variable depending upon such factors as deformation rate, temperature, and vibrational frequency. The stiffness of the main panel will not be significantly affected by the addition of the patch. For analysis purposes, the stiffness of a stamping from LVDSP should be taken as that of the monolithic main panel.

Laminate Core. The core shall consist of a viscoelastic resin that exhibits adequate bonding, temperature stability, strength, and plasticity to provide the required damping and manufacturing performance of the composite. A Material Safety Data Sheet (MSDS) shall be provided along with information on potential toxicity and odor emissions through the resistance welding temperature ranges.

Laminate Steel Skins. Most applications are specified as cold rolled low carbon sheet steels per GMW2, but others may be considered with approval from Materials Engineering. Additional development may be required. Both the main steel blank and steel skins may be specified as uncoated or double-sided galvanized per GMW8 or GMW11, with approval from GM Materials Engineering.

Material Identification. This specification shall be included in the engineering drawing material callout and the related manufacturing documents (i.e., the Manufacturing Engineering Metal Part Specification (MPS) Sheet).

Symbols. Not applicable.

Applicability. LVDSP is to be used in applications intended for noise and vibration harshness (NVH) reduction on the vehicles. For example, a dash panel could be optimized for NVH reduction with laminated patches after engineering design, manufacturing, and performance validation