1、 WORLDWIDE ENGINEERING STANDARDS Material Specification GMW15174 Constrained Layer Dampers Nonreactive Copyright 2012 General Motors Company All Rights Reserved January 2012 Originating Department: GME Specification Center Page 1 of 11 1 Scope This standard details the material and performance requi
2、rements for pressure sensitive constrained layer dampers. These types of materials shall be utilized for local vibration and sound damping. 1.1 Material Description. Constrained layer dampers are composed of a viscoelastic layer which is laminated to a constraining layer. The viscoelastic layer is t
3、ypically butyl-rubber based, self-adhesive and non-reactive. The constraining layer is typically a thin sheet of aluminum. Aluminum constraining layers shall comply with SAE J454. Only constraining layers that have been validated as meeting the performance requirements of this standard shall be allo
4、wed. The part is supplied with the adhesive surface protected by a temporary release paper. 1.2 Symbols. Not applicable. 1.3 Typical Applications. These materials are typically applied manually at Body Shop, Paint Shop or Trim Shop. Use should be restricted to relatively flat or gently contoured pan
5、els so that complete contact of this material to the panel can be assured. After application these constrained layer dampers shall be pressed on for optimum wet out. Typical application areas include vertical surfaces such as inner surfaces of door outer panels and inner surfaces of quarter outer pa
6、nels, and inverted surfaces such as inner surfaces of decklid outers and inner surfaces of roof outer panels. 1.4 Remarks. Not applicable. 2 References Note: Only the latest approved standards are applicable unless otherwise specified. 2.1 External Standards/Specifications. ASTM D2369 ISO 8510-2 ISO
7、/TS 16949 SAE J454 SAE J1637 2.2 GM Standards/Specifications. 9986321 GMW3008 GMW3221 GMW14872 GMW15735 GMW2 GMW3011 GMW3232 GMW15192 GMW16152 GMW8 GMW3059 GMW14019 GMW15416 GMW16700 GMW11 GMW3182 GMW14124 GMW15477 GMW16723 GMW3002 GMW3182 GMW14692 GMW15634 L 000 0131 GMW3005 GMW3205 GMW14729 GMW156
8、35 2.3 Additional References. EPA Method 24 TMC003 Material Safety Data Sheet guidance documents (available at ). 3 Requirements Unless otherwise specified, the following requirements shall be met. All testing shall be performed with materials that are representative of production processes. 3.1 Req
9、uirements on Test Specimens. Reference GMW3221, Code D. Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW15174 Copyright 2012 General Moto
10、rs Company All Rights Reserved January 2012 Page 2 of 11 3.2 Physical Requirements 3.2.1 Thickness. The maximum total thickness of the constrained layer damper shall not exceed 4.5 mm. Report the following, as tested: x Total thickness of the composite material x Thickness of the viscoelastic layer
11、x Thickness of the constraining layer x Description of the constraining layer 3.2.2 Weight per Unit Area. Report the weight per unit area as tested according to GMW3182. Guideline values of material weight per unit area corresponding to low, medium and high loss factor performance are shown in Table
12、 1. Table 1: Guideline Values of Weight per Unit Area for Each Loss Factor Grade Loss Factor Grades Loss Factor Code Typical Weight per Unit Area in kg/m Low LF-L 2.5 Medium LF-M 3.5 High LF-H 4.5 Note that lightweight constrained layer dampers may provide similar damping performance at lower mass.
13、Such materials can also be qualified to the corresponding loss factor grades. 3.2.3 Odor. The material shall have a neutral odor that is not unpleasant in the uncured condition. 3.2.4 Plant Emissions. 3.2.4.1 Plant Emissions Volatile Organic Compounds (VOC) Determination (EPA Method 24), paragraph 6
14、.2 using ASTM D2369 Method E). EPA Method 24 is required for US and Canada. For US, Hazardous Air Pollutants (HAPs) shall be 1 % by mass maximum, based on Material Safety Data Sheet (MSDS) formula. Local plant review and approval may be required prior to each new plant implementation of this materia
15、l. 3.2.4.2 Oven Condensing Volatiles Test. Test according to GMW3016. Evaluate after Maximum bake according to paragraph 3.3.2.3, followed by 2 h at (+23 5) C. VOC shall be 2 % by mass maximum. If reported VOC exceeds 2 % by mass, the composition of the VOC shall be declared. 3.2.5 Flame Resistance
16、(GMW16723). The material shall resist 50 passes with an open flame and be self-extinguishing. 3.3 Performance Requirements for Constrained Layer Dampers after run-through the Plant Process. 3.3.1 Composite Vibration Damping Properties. According to SAE J1637, Beam Size B. Constrained layer damper ca
17、ndidates shall be evaluated for acoustic performance per SAE J1637. The composite loss factors shall be measured at each specified temperature according to SAE J1637 for the 2nd, 3rd, 4th and 5th vibration modes of the test sample according to SAE J1637. The measured composite loss factors shall be
18、interpolated or extrapolated to values at 200 Hz, 400 Hz, 600 Hz and 800 Hz at each specified temperature. The constrained layer dampers are graded based on frequency minimum composite loss factor performance. The minimum composite loss factor is the minimum value in composite loss factors over 200
19、Hz, 400 Hz, 600 Hz and 800 Hz at each specified temperature. Table 4 specifies the lower limits of composite loss factor performance for each material grade. Material shall be evaluated at non bake condition and after maximum bake according to paragraph 3.3.2.3. The tests shall be performed with fol
20、lowing dimensions: Test bar dimensions: Total length: 241 mm Free length: 216 mm Width: 12.7 mm Thickness: 1 mm Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE EN
21、GINEERING STANDARDS GMW15174 Copyright 2012 General Motors Company All Rights Reserved January 2012 Page 3 of 11 Test bar quality: Spring steel (CK 75 according to DIN 1544 or C 75 S according to EN 10140) or equivalent. Test material dimensions: Length: 215 mm (from the edge) Width: 12.7 mm Thickne
22、ss: according to paragrah 3.2.1 The test material shall meet one of the following minimum loss factor grades in Table 2. The test results shall be provided in tabular and graphical form according to SAE J1637. Table 2: Performance Levels of Composite Loss Factors Frequency Minimum Composite Loss Fac
23、tors Temperatures in C Low (LF-L) Medium (LF-M) High (LF-H) -20 0.03 0.03 0.04 -5 0.05 0.06 0.07 +10 0.07 0.10 0.15 +25 0.09 0.18 0.28 +40 0.08 0.15 0.23 +55 0.04 0.07 0.12 Note: Measurement shall start at +55 C to get reproducable and condensate unaffected results. 3.3.2 Resistance to 180 Peel, Adh
24、esion and Corrosion. Constrained layer damper candidates shall be evaluated for resistance to peel according to ISO 8510-2, Separation mode and corrosion. Peel speed: 100 mm/minute. 3.3.2.1 Substrates. Testing shall be completed with the substrates in Table 3. Table 3: Substrates Substrate Descripti
25、on by Application Area For Body Shop Application:Note 1 Oily Cold Rolled Steel (CRS) (GMW2) Oily Hot Dipped Galvanized Steel (HDG) (GMW8), 60 g/m2 galvanized coating weight Oily Electrogalvanized Steel (EG) (GMW11), 60 g/m2 galvanized coating weight Oily Aluminum (AL) (GMW15192) Oil quality: Use one
26、 challenging GMW14019 approved lubricant as specified by the approving material engineer. For Paint Shop Application: Elpo: Use one widely used, GMW3008 approved Elpo as specified by the approving material engineer. For Trim Shop Application: Elpo: Use one widely used, GMW3008 approved Elpo as speci
27、fied by the approving material engineer. ELPO + Primer Overspray + Top Coat Overspray: Use one widely used GMW 3008 approved ELPO, GMW3002 approved Primer and GMW3005 Top Coat as specified by the approving material engineer. Overspray is a discontinuous film. Note 1: After application of the damping
28、 patches, the oily metal panels shall be processed through pretreatment and ELPO prior to baking and exposure according to paragraph 3.3.2.4.4 corrosive tests. Use any GM approved pretreatment (GMW3011) and ELPO (GMW3008) at target film thickness, as specified by the approving engineer. Copyright Ge
29、neral Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW15174 Copyright 2012 General Motors Company All Rights Reserved January 2012 Page 4 of 11 3.3.2.2 Tes
30、t Piece Preparation. Processing temperature of the damping film is (+20 to +40) C. Dimensions and preparation according to ISO 8510-2. For Body Shop Application degreasing and oiling of the substrates according to GMW15477. In deviation to ISO 8510-2 use a (2000 20) g roller for pressing on the test
31、 material by rolling twice in each direction at a speed of 10 mm/s without applying additional force. Allow test pieces to age for a minimum of 24 h at (+23 5) C following any specified bake, prior to exposure to any test environments, unless otherwise specified. 3.3.2.3 Bake Conditions. All bakes a
32、re specified as times at metal temperature, and defined in Table 4. Panels shall be baked horizontally, unless otherwise specified. Table 4: Bake Conditions Bake Description Bake Conditions (Time at Metal Temperature) Body Shop Applications Minimum 15 minutes at +160 C Maximum 60 minutes at +190 C P
33、aint Shop Applications Minimum Not required, trim is worst case minimum bake Maximum 60 minutes at +190 C Trim Shop Applications Minimum None Maximum none 3.3.2.4 Test Environments for Resistance to Peel, Adhesion and Corrosion. Evaluate for peel resistance, separation mode and corrosion. See Append
34、ix A for a graphic classification of Test Environments to application areas/substrates. For following tests evaluate the classified substrates with the respective bakes according to paragraph 3.3.2.3. 3.3.2.4.1 Initial. According to the application area testing shall be completed after adhesive cure
35、 or non cure, followed by a minimum of 24 h aging at (+23 5) C. 3.3.2.4.2 Cold Test. Testing shall be completed after a minimum of 24 h aging at -40 C. Testing shall be completed immediately upon removal of the test sample from the freezer. Actual test temperature shall be recorded and reported as p
36、art of the test. 3.3.2.4.3 Hot Test. Testing shall be completed after 120 h aging at +80 C. Two sample sets are required. One sample set shall be tested at the test temperature and the other set shall be tested at +23 C after a minimum of 24 h “recovery” from environment. 3.3.2.4.4 Corrosive Tests.
37、3.3.2.4.4.1 Thermal Cycle (GMW14124, Cycle I, 10 cycles). Testing shall be completed after a minimum of 24 h “recovery” from environment. 3.3.2.4.4.2 Corrosion (GMW14872 (Underbody (UB), All, 4 salt sprays (4s), Method 1/2, Exposure D). Evaluate only oily substrates according to paragraph 3.3.2.1. T
38、esting shall be completed after a minimum of 24 h “recovery” from environment. 3.3.2.4.4.3 Water Immersion. Testing shall be completed after 168 h water storage (adhesive area is completely dipped in deionized water) at +55 C. Testing shall be done after a minimum of 24 h “recovery” from environment
39、. 3.3.2.5 Evaluation Criteria. After exposure to the Test Environments according to paragraph 3.3.2.4, visually inspect the damper for any unusual effects. Perform Resistance to Peel testing according to ISO 8510-2 to evaluate the peeling force (N/cm) and evaluate the area beneath the damper. Copyri
40、ght General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW15174 Copyright 2012 General Motors Company All Rights Reserved January 2012 Page 5 of 11 3.3.2
41、.5.1 Adhesion and Corrosion. The evaluation criteria for Adhesion and Corrosion is summarized in Table 5. 3.3.2.5.2 Peeling Force. Exhibiting resistance to peel according to ISO 8510-2: Minimum peel values (N/cm) are summarized in Table 5. Table 5: Evaluation Criteria Substrates Noncorrosive Tests (
42、Paragraph) 3.3.2.4.4 Corrosive Tests (Paragraph) 3.3.2.4.1 Initial 3.3.2.4.2 Cold Test 3.3.2.4.3 Hot Test 3.3.2.4.4.1 Thermal Cycle I 3.3.2.4.4.3 Water Immersion 3.3.2.4.4.2 Corrosion Body Shop Substrates Minimum peel value of 11 N/cm or t 80 % cohesive separation. No corrosion under damper and no u
43、ndercutting. Paint Shop Substrates Minimum peel value of 11 N/cm or t 80 % cohesive separation. No corrosion under damper and no undercutting. Testing not required. Trim Shop Substrates Minimum peel value of 11 N/cm or t 80 % cohesive separation. No corrosion under damper and no undercutting. Testin
44、g not required. 3.3.3 Water Absorption (GMW16152, 24 h Immersion). A non cured material sample and maximum cured material sample according to paragraph 3.3.2.3 shall exhibit a water absorption 6 N/cm or t 80 % cohesive separation 11 N/cm or t 80 % cohesive separation Paint Shop Substrates 11 N/cm or
45、 cohesive separation Trim Shop substrates 11 N/cm or cohesive separation 3.4.5.2 Sag and Slide. Evaluate one challenging test substrate per application area for Body Shop and Paint Shop according to paragraph 3.3.2.1 with the respective maximum bakes according to paragraph 3.3.2.3. Test Piece Prepar
46、ation according to paragraph 3.3.2.2. In deviation to paragraph 3.3.2.2 test panel dimension shall be 250 mm x 100 mm minimum, and test sample dimension 150 mm x 50 mm. Store the panel for 24 h at (+23 5) C, and then bake as described at beginning of this paragraph. During storage and baking, one pa
47、nel set shall be positioned vertically so that the length of the material is in a horizontal position and another panel set shall be positioned inverted. After cooling to (+23 5) C, the applied material shall be evaluated. No loss of adhesion (sag) and no movement (slide) is allowed. 3.4.5.3 Wash Of
48、f Resistance (only for Body Shop Application). According to GMW16700. Evaluate oily HDG substrate according to paragraph 3.3.2.1. Test sample dimension shall be 150 mm x 50 mm. 2 h after application the material shall not fall off or be displaced from contact with the degreasing, pretreatment or ELP
49、O coating processes. For initial material approval, successful performance shall be demonstrated either using method A (no pre-gel is allowed) or method B (Rating 5). 3.4.6 Compatibility with Plant Materials and Processes. Prior to implementation of any part containing this material into an assembly plant, compatibility testing with unique plant specific materials (example: lubricants, substrates) and/o
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