FORD FLTM BO 111-04-2001 DYNAMIC ENERGY ABSORPTION OF POLYURETHANE FOAM《聚氨酯泡沫的动态能量吸收性能》.pdf

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1、 FORD LABORATORY TEST METHOD BO 111-04 Date Action Revisions 2001 03 28 Revised Editorial no technical change A. Cockman 1996 10 22 Printed copies are uncontrolled Page 1 of 9 Copyright 2001, Ford Global Technologies, Inc. DYNAMIC ENERGY ABSORPTION OF POLYURETHANE FOAM Application This test method e

2、valuates the dynamic energy absorption capability of polyurethane foam used to fabricate side impact bolsters for use in door trim panels. Test Samples The standard test sample is a 254.0 x 254.0 x 63.5 mm block of foam with a 5 draft angle as shown in Figure 1. Apparatus Required Impacting Assembly

3、 Consisting of the following (see Figure 2): Impactor Type I or Type II Note: Use Type I impactor unless otherwise specified: Type I: Half cylinder An aluminum half cylinder of 6.35 mm wall thickness with an external diameter of 152.4 mm and an overall length of 330.2 mm mounted via aluminum extensi

4、ons to a 12.7 mm thick aluminum plate of equal length and 196.85 mm wide. When affixed to and traveling with the impact carriage, the axis of the impactor half cylinder must be vertical when viewed from the front and from the side. Type II: Flat Square A flat aluminum plate 12.7 mm thick 165.1 mm lo

5、ng and 165.1 mm wide mounted via aluminum extensions to an aluminum plate 12.7 mm thick 330.2 mm long and 196.9 mm wide. When affixed to and traveling with the impact carriage, the impacting surface of the plate and its side edges must be vertical and the impacting surface of the plate must be perpe

6、ndicular to the direction of carriage travel. Impact Carriage A moveable assembly which when combined with the impactor weighs 18.14 kg and is capable of being accelerated so as to attain a constant speed in free-flight of at least 35.4 km/h just prior to impact. FORD LABORATORY TEST METHOD BO 111-0

7、4 Page 2 of 9 Copyright 2001, Ford Global Technologies, Inc. Contact Switch (bullet end) An electrically isolated copper foil contact switch is applied to the surface of the impactor along the vertical centerline such that it comes into contact with its counterpart on the impacted assembly. Impacted

8、 Assembly Consisting of the following (see Figure 3): Test Sample When the sample as described above is secured according to the test procedure outlined below, it forms a part of the impacted assembly. Sample Fixture Fixturing the sample is accomplished using side supports which mount to the load ce

9、ll. These supports hold the sample in position prior to testing and provide lateral constraint to the sample during impact. These constraints are evident in the detail of figure 3. Load Cell The load cell is mounted between the sample fixture and the rigid facility backplate. It must form the only p

10、ath by which load transferred from the sample through the sample fixture during impact can reach the rigid facility backplate; and thus measure the entire load imparted to the sample at impact. Load cell specifications are detailed in the instrumentation section. Rigid Facility Backplate The rigid f

11、acility backplate must provide any horizontal and vertical adjustment necessary to position the sample fixture such that the line of travel of the mass center of the impacting assembly passes through the center of the test sample. Further the backplate must provide any rotational adjustment necessar

12、y to align the sample fixture so that the impacted surface of the constrained sample is perpendicular to the line of travel of the mass center of the impacting assembly when viewed from the side and form above. LVDTs The LVDT body(ies) is/are mounted to the rigid facility backplate. Its/their core(s

13、) pass through the backplate, sample fixture, and sample itself. A nut-plate is threaded onto the end of each LVDT core and set flush with the sample surface to measure the crush deflection of the surface of the sample. LVDT specifications are detailed in the instrumentation section. (Note that the

14、Type I cylindrical impactor uses two (2) LVDTs while the Type II flat impactor uses only one (1).) Contact Switch (target end) A piece of copper foil is applied to the end nut/plate of the lower LVDT core and set flush with the sample surface such that it will contact the foil on the impacting assem

15、bly at the time of crush initiation. FORD LABORATORY TEST METHOD BO 111-04 Page 3 of 9 Copyright 2001, Ford Global Technologies, Inc. Instrumentation Load Cell(s) The load cell(s) must be capable of measuring force loading on three orthogonal axis and may additionally measure bending moments. Bendin

16、g moments must, however, be cancelled from the measured forces. A single load cell when used for material measurements must have a full scale of at least 44,480 N but not to exceed 88,960 N. In order to maintain a sufficiently high system natural frequency, overall load cell stiffness in the X & Y d

17、irections should be 1.75x106 N/mm minimum and in the Z direction 4.38x106 N/mm minimum. Axis definitions may be found in Figure 4. A Denton Model No. 3102 satisfies these requirements and is shown in reference Figures 3 and 4. LVDTs Linearity: 0.25 % deviation from Best Fit Straight Line Linear rang

18、e: 101.6 +/- 12.7 mm Frequency response: 1000 Hz minimum Switches Contact The contact switch is comprised of two pieces of copper foil, one affixed to the impactor, the other to the impacted sample, which complete a circuit upon contact. Motion initiation This switch is a proximity type switch used

19、to indicate the start of carriage motion and signaling the beginning of data collection. Speed Trap The speed trap must be capable of measuring carriage velocity just prior to impact to +/- 0.16 km/h. Test Set-up Assembly The impacting and impacted assemblies as described above are assembled accordi

20、ng to the assembly drawings of Figures 2 and 3. Figure 3 Shows LVDT placement for the Type II, flat square impactor assembly. One LVDT is used with its core rod extending through the central hole of the single load cell. The Type I, cylindrical impactor assembly, requires 2 - LVDTs (see page 2) spac

21、ed apart vertically in the holes shown about the central LVDT position in Figure 3. The test sample is left out of the impacted assembly until testing as described in the test procedure below. Figure 4 shows the assembled apparatus and details the alignment described below. FORD LABORATORY TEST METH

22、OD BO 111-04 Page 4 of 9 Copyright 2001, Ford Global Technologies, Inc. Alignment (See Figure 4) With the carriage located at the position of contact the impactor is adjusted such that the axis of the impactor is vertical when viewed from the side and from the front. The facility backplate and sampl

23、e fixture are adjusted for linear position such that: The fixture surface is located longitudinally so that full travel of the carriage allows it to contact the load cell when the sample is not in place. The load center of the fixture and load cell assembly is on the line of travel of the mass cente

24、r of the impacting assembly. The facility backplate and sample fixture are rotated to accomplish orientational adjustment such that: The top surface of the fixture and test sample are horizontal. The fixture surface parallel to the impacted surface of the test sample is vertical when viewed from the

25、 side. The fixture surface parallel to the impacted surface of the test sample is perpendicular to the direction of carriage travel when viewed from above. Final Setup A sacrificial test sample is inserted into and secured in the test fixture. The speed trap is positioned to record carriage velocity

26、 in free-flight 6.35 mm prior to impact. The LVDT(s) is/are positioned such that its/their core(s) may travel freely in the direction of impact. The apparatus is test fired to verify: That the impact speed is within specified tolerance limits and as close as possible to specified speed. (Unless othe

27、rwise specified, the impact speed assumed in this procedure is 24.1 km/h.) That the data collection is proceeding as expected and there are no unexpected anomalies. Conditioning and Test Conditions All test values indicated herein are based on material conditioned in a controlled atmosphere of 23 +/

28、- 2 C and 50 +/- 5 % relative humidity for not less than 24 h prior to testing and tested under the same conditions unless otherwise specified. FORD LABORATORY TEST METHOD BO 111-04 Page 5 of 9 Copyright 2001, Ford Global Technologies, Inc. Test Procedure The test sample is placed in the fixture and

29、 the side constraint wedges are installed to hold the sample firmly in place. Next a hole(s) is/are bored in the conditioned test sample to accommodate the displacement measuring LVDT core(s). In boring this/these hole(s) care must be taken to avoid coning type damage to the test sample surface. Usi

30、ng a sharp instrument, spear the sample through from the back side of the LVDT casing until the tip touches the skin of the contact surface. Manually twist-drill into the front surface. Remove spear and drill and push LVDT core(s) through the front surface and sample into the casings. Care must be t

31、aken to ensure that the LVDT core(s) can travel freely. The carriage is positioned to begin testing and the contact switches are checked to verify function. The impacting assembly is accelerated toward the test sample and coasts in free-flight into the sample crushing the sample while data is collec

32、ted on the event. Once data collection and download are complete, necessary photographs are taken, constraint wedges are removed, and the crushed sample remains are removed for the next test. Table 1 Butterworth Digital Filter Classes Data Channel Type Filter Class Load Cell 1000 LVDT 1000 Switch 40

33、00 Filter Classes have been selected mindful of SAE J211 “Instrumentation for Impact Tests“. Deviation from this standard may have been implemented in certain instances to avoid distortion of the final information when processed using the prescribed data analysis procedure. Data Acquisition Data col

34、lection begins with the initiation of carriage motion and continues through the duration of the impact event. Data is collected on all channels at a sampling rate of 12.5 kHz with a 4000 Hz anti-aliasing hardware filter. Prior to processing collected data is further filtered using a 2 pole Butterwor

35、th type digital filter with the filter class for each channel as specified in table 1. FORD LABORATORY TEST METHOD BO 111-04 Page 6 of 9 Copyright 2001, Ford Global Technologies, Inc. Data Analysis and Presentation This procedure must be followed to address LVDT/load concerns noted below.* Determine

36、 Time Zero Using the closing of the contact switch as a guide, examine the Load vs. Time curve during the window beginning 1.5 ms prior to indicated contact and ending 3.5 ms after indicated contact. Look for the data point nearest to 890 N. Determine the load and time associated with this data poin

37、t. Likewise look for the data point nearest to 2890 N and determine the load and time associated with it. Pass a line through these two points which intersects the time axis. The time value of the nearest data point is to be used as Time Zero. (Note that these reference loads - 890 & 2890 N - are sp

38、ecific to a 24.1 km/h impact speed and may need to be adjusted for other speeds.) Value Shift Each LVDT Curve Individually for each LVDT curve: Determine the displacement value of the LVDT curve at Time Zero. Use this value as the offset to shift the entire LVDT curve such that the LVDT curve now sh

39、ows a zero displacement at Time Zero. (i.e. vertically subtract this displacement offset from every point on the LVDT curve.) Average LVDT Curves If two LVDTs are present, average the two value shifted LVDT curves to get an average Displacement vs. Time curve. Time Shift Load vs. Time and Average Di

40、splacement Curves Time shift the Total Load vs. Time and Displacement vs. Time curves by the Time Zero amount determined above so that “zero load“ and “zero displacement“ both occur at “zero time“. Calculate Unit Load vs. Time Using Load vs. Time and the Displacement vs. Time curve along with the ge

41、ometry of the impacting assembly calculate Unit Load vs. Time. For the Type I cylindrical impactor described in this procedure P(t) = L(t) 2l d D(t) D(t) where P(t) = Unit Load vs. Time L(t) = Load vs. Time D(t) = Displacement vs. Time d = Cylinder Diameter l = Cylinder Impact Length FORD LABORATORY

42、 TEST METHOD BO 111-04 Page 7 of 9 Copyright 2001, Ford Global Technologies, Inc. For the 152.4 mm diameter half cylinder with a 254 mm impacting length diameter and length values are d = 152.4 mm l = 254.0 mm For the flat square impactor simply divide the load vs. time curve by the impactor area. C

43、alculate Crush Percent vs. Time Divide the Displacement vs. Time curve by the sample thickness, here 63.5 mm and multiply by 100 % to determine Crush Percent vs. Time. Cross Plot Load vs. Displacement Correlating the time values of the shifted Load vs. Time and Displacement vs. Time curves create a

44、cross plot of Load vs. Displacement. Cross Plot Unit Load vs. Crush Percent Correlating the time values of the shifted Unit Load vs. Time and Crush Percent vs. Time curves create a cross plot of Unit Load vs. Crush Percent. Data shall be presented in both Load vs. Displacement and Unit Load vs. Crus

45、h Percent formats. Data presented with these curves shall include: impact velocity, material supplier, sample number, test date, and any further notes or comments concerning the particular test. * The data analysis procedure outlined above has been specified to address the following concern: It has

46、been observed that, differences in positioning of multiple LVDT cores and differences in soldering technique and contact switch positioning, a substantial amount of apparent displacement has occurred before any loading of the foam takes place. Chemicals, materials, parts, and equipment referenced in

47、 this document must be used and handled properly. Each party is responsible for determining proper use and handling in its facilities. FORD LABORATORY TEST METHOD BO 111-04 Page 8 of 9 Copyright 2001, Ford Global Technologies, Inc. FORD LABORATORY TEST METHOD BO 111-04 Page 9 of 9 Copyright 2001, Ford Global Technologies, Inc.