GMW GMW16425 PDF

Note: Nothing in this standard supercedes applicable laws and regulations.

Note: In the event of conflict between the English and domestic language, the English language shall take precedence.

Material Description. The material defined by this specification is a laminated vibration damping steel patch (LVDSP) consisting of either two similar or dissimilar metal sheets of the same or different thickness separated by, and bonded by, a visco-elastic core. The patch blanks shall be applied on interior surfaces, which are not exposed to corrosive environments. 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 visco-elastic 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 steels skins may be specified as uncoated, or with a double-sided electroplated coating as specified in GMW11. Hot dip coatings may be available as LVDSP but shall not be specified without approval of Materials Engineering.

Material Identification. This specification shall be included in the engineering drawing material callout and the Manufacturing Engineering Metal Part Specification (MPS) Sheet. The materials shall be identified by their gauge and grade, followed by this specification number for requirements of the laminated composite sheet. See Section 7 for examples.

Symbols. Not applicable.

Typical Applications. 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.

Remarks. Not applicable.