Scott Noll, Sheng Dong, Yun-Seok Kang, John Bolte, Jason Stammen, Kevin Moorhouse
{"title":"Experimental Assessment of Human and Crash Dummy Skin to Vehicle Air Bag Fabric Coefficients of Friction","authors":"Scott Noll, Sheng Dong, Yun-Seok Kang, John Bolte, Jason Stammen, Kevin Moorhouse","doi":"10.4271/09-11-03-0014","DOIUrl":"https://doi.org/10.4271/09-11-03-0014","url":null,"abstract":"<div>Oblique motor vehicle crashes can cause serious head or brain injuries due to contact with interior vehicle structures even with the deployment of air bags, as they are not yet completely successful in preventing traumatic brain injury. Rotational head velocity is strongly correlated to the risk of brain injury, and this head motion is potentially related to the tangential friction force developed during contact between the head and air bags. Although crash test dummy head skins are designed with appropriate mass properties and anthropometry to simulate the normal direction impact response of the human head, it is not known whether they accurately represent the frictional properties of human skin during air bag interaction. This study experimentally characterized the dynamic friction coefficient between human/dummy skins and air bag fabrics using a pin-on-disc tribometer. Human skin samples were harvested from five locations (left and right forehead, left and right cheek, and chin) from male and female postmortem human subjects (PMHSs); some samples had previously been frozen and some were fresh. Crash dummy head skin samples were obtained from Hybrid III, ES-2re, and THOR-50M 50th-percentile male anthropomorphic test devices (ATDs) and were characterized in both chalked and unchalked conditions. Fabric samples were obtained from five different air bags spanning various vehicle manufacturers and interior mounting locations. Neither sex, linear speed, nor the harvested skin location on the head played a significant role on the dynamic friction between PMHS skin samples and air bag fabrics, while PMHS skin samples that had not been previously frozen had a higher coefficient of friction than those that had. Further, increasing normal load reduced the dynamic friction coefficient between PMHS skin samples and air bag fabrics. Unchalked ATD head skins exhibited significantly higher dynamic friction coefficients than PMHS skins for the air bag fabrics tested. The presence of a thin chalk layer on ATD skins reduced friction and produced dynamic friction coefficients with air bag fabrics that were not significantly different from those of PMHS skins; however, neither unchalked nor chalked ATD head skins differentiated the air bag fabric dynamic friction coefficients in the same pattern as the PMHS skin samples.</div>","PeriodicalId":42847,"journal":{"name":"SAE International Journal of Transportation Safety","volume":"224 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135206232","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Criticality Metrics Study for Safety Evaluation of Merge Driving Scenarios, Using Near-miss Video Data","authors":"Takashi Imaseki, Fukashi Sugasawa, Eriko Kawakami, Hiroshi Mouri","doi":"10.4271/09-12-01-0002","DOIUrl":"https://doi.org/10.4271/09-12-01-0002","url":null,"abstract":"<div>In autonomous driving vehicles with an automation level greater than three, the autonomous system is responsible for safe driving, instead of the human driver. Hence, the driving safety of autonomous driving vehicles must be ensured before they are used on the road. Because it is not realistic to evaluate all test conditions in real traffic, computer simulation methods can be used. Since driving safety performance can be evaluated by simulating different driving scenarios and calculating the criticality metrics that represent dangerous collision risks, it is necessary to study and define the criticality metrics for the type of driving scenarios. This study focused on the risk of collisions in the confluence area because it was known that the accident rate in the confluence area is much higher than on the main roadway. There have been several experimental studies on safe driving behaviors in the confluence area; however, there has been little study logically exploring the merging actions with mathematical metrics. In light of this, this study introduces a criticality metric representing the risk of a collision in a junction area. The metric calculates the reaction level required to avoid a predicted collision risk; therefore, a safety evaluation can be performed by assessing the reaction effort to prevent such collisions in a driving scenario. The near-miss video data from the database is used to validate the proposed metric for the merging scenario. The database contains various real merging scenarios experienced by human drivers. The proposed metric was validated to identify a critical situation with collision risks and a safe driving situation that can prevent collisions easily, using sample data of merging scenarios from the database. Moreover, an example application for safety assessment was investigated. In summary, the safety performance of autonomous driving vehicles in merging can be evaluated through simulations using the criticality metric. In the future, the results of this study could be applied to develop an on-board risk detection function in the confluence area.</div>","PeriodicalId":42847,"journal":{"name":"SAE International Journal of Transportation Safety","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135394352","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Hana Chan, Devon L. Albert, F. S. Gayzik, A. Kemper
{"title":"Occupant Kinetics and Muscle Responses of Relaxed and Braced Small\u0000 Female and Midsize Male Volunteers in Low-Speed Frontal Sled\u0000 Tests","authors":"Hana Chan, Devon L. Albert, F. S. Gayzik, A. Kemper","doi":"10.4271/09-11-03-0012","DOIUrl":"https://doi.org/10.4271/09-11-03-0012","url":null,"abstract":"Previous volunteer studies focused on low-speed frontal events have demonstrated\u0000 that muscle activation (specifically pre-impact bracing) can significantly\u0000 affect occupant response. However, these tests do not always include a\u0000 sufficient number of small female volunteers to compare their unique responses\u0000 to the typically studied midsize male population. The purposes of this study\u0000 were to quantify the occupant kinetics and muscle responses of relaxed and\u0000 braced small female and midsize male volunteers during low-speed frontal sled\u0000 tests and to compare between muscle states and demographic groups. Small female\u0000 and midsize male volunteers experienced multiple low-speed frontal sled tests\u0000 consisting of two pulse severities (1 g and 2.5 g) and two muscle states\u0000 (relaxed and braced) per pulse severity. The muscle activity of 30 muscles (15\u0000 bilaterally) and reaction forces at the volunteer-test buck interfaces and seat\u0000 belt were measured before and during each sled test. Compared to the relaxed\u0000 muscle state, bracing generally increased pre-test muscle activity and pre-test\u0000 forces, delayed muscle activation (relative to the pre-test value) in response\u0000 to the sled pulse, and increased peak forces during the sled tests. However,\u0000 relaxed volunteers exhibited greater changes in muscle activity and reaction\u0000 forces relative to the pre-test value. Males exhibited higher peak forces across\u0000 all reaction surfaces during the sled tests compared to females, but peak muscle\u0000 activity varied as to whether males or females exhibited higher activation. The\u0000 upper extremity muscles activated the most during pre-test bracing, while the\u0000 upper extremity, trunk, and neck muscles activated the most during the sled\u0000 tests.","PeriodicalId":42847,"journal":{"name":"SAE International Journal of Transportation Safety","volume":" ","pages":""},"PeriodicalIF":0.5,"publicationDate":"2023-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49137541","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}