Review of Department of Defense Test Protocols for Combat Helmets (2014) / Chapter Skim
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8 Lot Acceptance Testing
8 Lot Acceptance Testing
Pages 54-63
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From page 54... ...
standard, 8.2 LOT ACCEPTANCE TESTING PROTOCOLS and they vary by lot size. This chapter examines the operating characteristic (OC)
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The protocol established by the The DOT&E LAT protocol makes no mention of helmet Director, Operational Test and Evaluation, should be revised size. If lots consist of only one helmet size, then it is clear TABLE 8-3 Helmet Shot Order Test Matrix for Aramid 9-mm Helmet Order LAT Helmet #1 B L Cr F R LAT Helmet #2 Cr R B L F LAT Helmet #3 R B Cr L F LAT Helmet #4 B F L R Cr LAT Helmet #5 B R F L Cr LAT Helmet #6 Cr B L F R LAT Helmet #7 L B Cr F R LAT Helmet #8 Cr B R F L LAT Helmet #9 L F R B Cr LAT Helmet #10 F Cr B L R LAT Helmet #11 Cr L R B F LAT Helmet #12 R F B L Cr LAT Helmet #13 Cr F L B R NOTE: B, back; CR, crown; F, front; L, left; R, right; LAT, lot acceptance testing.
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first stage RTP test described above, then passing the LAT It is difficult to match the OC curves very closely if one BFD requirement is based on all of the data collected and the wishes to vary the sample sizes for different lot sizes and, accept/reject criterion specified for the lot size. As before, in particular, fix the sample sizes using the ANSI standard.
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: 80 percent UTL for lot sizes of 501 to 3,200 helmets, 75 percent As discussed in Chapter 6, the problem illustrated in Fig- UTL for lot sizes of 151 to 500 helmets, and a more compliure 8-2 is with DOT&E's (17, 240) FAT protocol.
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FAT protocol and DOT&E's FAT Backface Deformation Lot Acceptance Testing Protocols protocol for BFD. These results are based on a simulation Based on Binary Data study conducted under the following scenario: As noted in Chapter 7, there are many difficulties with • The BFD measurements are normally distributed.
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5) .5 Determining the Acceptance Quality Limit The result of this requirement is that, if a penetration occurs, The helmet sample sizes in Table 8-1 are derived from the the number of helmets sampled will not match the sample ANSI standard special inspection level6 S-2 for the hardware size in Table 8-1 or the ANSI standard.
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S-3 35,001-150,000 32 0/1 S-3 150,001-500,000 32 0/1 8.5 USING THE HELMET AS THE UNIT OF TESTING S-4 500,001+ 125 1/2 Helmet-Based Lot Acceptance Testing Protocols SOURCE: Adapted from ASQ (2008)
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specifically says, FIGURE 8-5 Operating characteristic (OC) curves for the illustra- The concept of AQL only applies when an acceptance tive helmet-based lot acceptance testing (LAT)
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TABLE 8-7 Switching Rules for Lot Sizes of 1,200 to If a manufacturer under the normal regime has 10 con- 3,200 with Acceptance Quality Limit of 0.4 secutive lots accepted, then it is switched to reduced rules Accept/Reject that make it easier to pass the LAT. However, as soon as it Sample Size Criteria (Number of (Number of fails a lot while under the reduced rules, the manufacturer is Switching Rule Lot Size Helmets)
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2012. Standard for Lot Acceptance Ballistic Testing of Military Combat Helmets.
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