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Mengqi Yuan - One of the best experts on this subject based on the ideXlab platform.

  • Structural design of a 3-D printed stab resistant Body Armor
    Rapid Prototyping Journal, 2019
    Co-Authors: Gong Zheng, Xinming Qian, Mengqi Yuan
    Abstract:

    Stab-resistant Body Armor (SRBA) can protect the human Body from injury as a result of stabbing by sharp projectiles. However, in its current design SRBA, it has not been widely adopted for use, because of its weight and poor flexibility. Herein, this paper aims to detail a new type of SRBA that is inspired by the Armor plating of mammals and is fabricated using laser sintering (LS) technology.,This new type of SRBA was fabricated using LS technology. The laser sintered SRBA was subjected to a stab resistance performance test that conformed to the GA 68-2008 Chinese National Standard. The stab resistance response of the novel structured, stab resistance test plates in this study was analyzed using the using the AUTODYN explicit module in ANSYS-Workbench.,The structure of the novel stab resistance plate was designed and the optimum structural parameters were tested, discussed and achieved. The mechanism of dissipation of the impact energy by the pyramidal structures of the novel SRBA was studied, and it was found that this structure dispersed the kinetic energy of the knife and minimized the structural damage to the plate. Interlinks inspired by the pangolin hierarchy structure were designed and used to fabricate a large piece of laser sintered Body Armor.,High-performance laser sintered stab resistance plate was produced via the material and structure studies, which could reduce 40 per cent weight on the stab resistance Body Armor and increase the wearability.

  • The application of PA/CF in stab resistance Body Armor
    IOP Conference Series: Materials Science and Engineering, 2017
    Co-Authors: Mengqi Yuan, Gong Zheng, Ying Liu, Xinming Qian
    Abstract:

    Stab resistance Body Armor (SRBA) is an essential defensive equipment to protect human Body against injuries from stabbing. The conventional SRBAs shared low wearing frequency since they are heavy and poor in flexibility. This paper designed a structured stab-resistance plate using the model of crocodile Armor and manufactured using 3D printing technology-laser sintering (LS). CF(Carbon fiber) was applied to enhance the stab resistance properties of SRBA. The effects of the material and structure were analysed through the stab resistance property tests based on the national standard GA68-2008. It is found that the stab resistance property of flat plates sintered by PA powder and PA/CF are both weaker than that of the structured plate. The penetrating depth of PA/CF structured plate is significantly 2-mm-less than the pure PA structured plate. The SEM observations confirmed the conclusion that addition of the CF largely improved the plate stab resistance property. Moreover, using PA/CF structured plate to produce the stab resistance Body Armor would result in a weight reduction by about 30-40% as compared to the existing SRBA that was made up of metal plates, which could largely reduce the wearer physical burden and improve the wearing frequency.

  • investigations on thermal insulation and vapor resistance of Body Armor using thermal manikin method
    Cmes-computer Modeling in Engineering & Sciences, 2015
    Co-Authors: Mengqi Yuan, M Fu, J Yang, J H Jiang, X M Qian
    Abstract:

    With the frequent occurrences of the violence incidents, research on Body Armor is paid much attention to. To study the human physiological responses when wearing Body Armor and to improve the wearing comfort of Body Armor, a thermal manikin was used to measure the thermal insulation and vapor resistance of two types of Body Armor (stab-resistance and bulletproof, respectively) in a climate chamber. Results show the coverage levels on Body part and material selections on protection layer affect the thermal insulation and vapor resistance of the Body Armors. Moreover, air temperature and relative humidity of the climate chamber have an influence on the moisture transfer of the Body Armors. The findings in this study could establish a data support for Body Armor, with thermophysical property improvement and design optimization. Keywords-stab-resistance; bulletproof; Body Armor; thermal manikin; thermal insulation; vapor resistance

Amanda L. Forster - One of the best experts on this subject based on the ideXlab platform.

  • Linking Theory to Practice: Predicting Ballistic Performance from Mechanical Properties of Aged Body Armor
    Journal of Research of the National Institute of Standards and Technology, 2020
    Co-Authors: Amanda L. Forster, Amy Engelbrecht-wiggans, Dennis D. Leber, Virginie Landais, Allen Chang, Emilien Guigues, Guillaume H.r. Messin, Michael A. Riley
    Abstract:

    It has long been a goal of the Body Armor testing community to establish an individualized, scientific-based protocol for predicting the ballistic performance end of life for fielded Body Armor. A major obstacle in achieving this goal is the test methods used to ascertain ballistic performance, which are destructive in nature and require large sample sizes. In this work, using both the Cunniff and Phoenix-Porwal models, we derived two separate but similar theoretical relationships between the observed degradation in mechanical properties of aged Body Armor and its decreased ballistic performance. We present two studies used to validate the derived functions. The first correlates the degradation in mechanical properties of fielded Body Armor to the degradation produced by a laboratory accelerated-aging protocol. The second examines the ballistic resistance and the extracted-yarn mechanical properties of new and laboratory-aged Body Armor made from poly(p-phenylene-2,6-benzobisoxazole), or PBO, and poly(p-phenylene terephthalamide), or PPTA. We present correlations found between the tensile strengths of yarns extracted from Armor and the ballistic limit (V50) when significant degradation of the mechanical properties of the extracted yarns was observed. These studies provided the basis for a validation data set in which we compared the experimentally measured V50 ballistic limit results to the theoretically predicted V50 results. The theoretical estimates were generally shown to provide a conservative prediction of the ballistic performance of the Armor. This approach is promising for the development of a tool for fielded Armor performance surveillance relying upon mechanical testing of Armor coupon samples.

  • Effects of temperature and humidity on high-strength p-aramid fibers used in Body Armor:
    Textile Research Journal, 2020
    Co-Authors: Amy Engelbrecht-wiggans, Faraz Burni, Emilien Guigues, S Jiang, Tq Huynh, Zois Tsinas, D Jacobs, Amanda L. Forster
    Abstract:

    To improve the reliability and design of Body Armor, it is imperative to understand the failure modes and the degradation rates of the materials used in Armor. Despite the best efforts of manufactu...

  • Tensile testing of aged flexible unidirectional composite laminates for Body Armor
    Journal of Materials Science, 2020
    Co-Authors: Amy Engelbrecht-wiggans, Faraz Burni, Ajay Krishnamurthy, Amanda L. Forster
    Abstract:

    Flexible unidirectional (UD) composite laminates are commonly being used for ballistic-resistant Body Armor. These laminates comprise UD layers, each constructed by laminating thin layers of high-performance fibers held in place using very low modulus binder resins, with the fibers in each layer oriented parallel to each other. As these materials are used in Body Armor, it is important to investigate their long-term reliability, particularly with regard to exposure to temperature and humidity as these are known causes of degradation in other commonly used Body Armor materials. This work investigates the tensile behavior of a poly( p -phenylene terephthalamide), or PPTA flexible UD laminate aged for up to 150 days at accelerated aging conditions of 70 °C and 76% relative humidity. Tests were performed at three different crosshead displacement rates and three different gauge lengths. The effect of aging on the mechanical properties of the material was observed as less than 10% degradation in tensile strength, with a more significant reduction in longer specimens when tested at slower rates.

  • Specifying and testing idealized bust surrogates for testing of female stab-resistant Body Armor
    Textile Research Journal, 2015
    Co-Authors: Amanda L. Forster, Emilien Guigues, Michael A. Riley, Kirk D. Rice, Anthony Chan-ou-teung, Aaron M. Forster
    Abstract:

    Manufacturers of stab-resistant Body Armor continually strive to improve the comfort of the Armor wearer and maximize protection. As female officers make up a larger portion of the law enforcement and corrections workplace, Armor manufacturers have begun to offer designs that accommodate contoured Body shapes, such as the female bust region, which results in non-planar Armor. Conventional test methodologies for Body Armor were designed for Armor to be tested flat and do not accommodate contoured Armor. This work reviews the available literature concerning common bust sizes and discusses the research performed to specify bust surrogate size, shape, and materials for testing stab-resistant female Body Armor. Two standard cup sizes, B and D, modeled as a paraboloid with a modified base, are recommended to meet breast volume requirements. Recommendations for manufacture of these surrogates for incorporation into standardized test methods are provided. Instrumented stab testing of these surrogates shows that i...

  • Hydrolytic stability of polybenzobisoxazole and polyterephthalamide Body Armor
    Polymer Degradation and Stability, 2011
    Co-Authors: Amanda L. Forster, Guillaume H.r. Messin, Michael A. Riley, Pierre Pintus, Sylvain H. Petit, Walter J. Rossiter, Joannie W. Chin, Kirk D. Rice
    Abstract:

    Previous work conducted at the National Institute of Standards and Technology (NIST) to investigate the field failures of soft Body Armor containing the material poly(p -phenylene-2,6-benzobisoxazole), or PBO, revealed that this material was susceptible to hydrolysis, and a mechanism of this hydrolysis was proposed. In this work, viscometric estimations of the molar mass of environmentally conditioned PBO are used to support a previously proposed mechanism of PBO hydrolysis. Results with PBO were compared with poly(p-phenylene terephthalamide), or PPTA, which has been used in Body Armor applications for more than 30 years. Losses in tensile strength were found to correspond to a reduction in molar mass for PBO. This indicates that chain scission due to complete hydrolysis is occurring in this material. Similar trends were observed for PPTA, but the relationship between molar mass reduction and losses in tensile strength was not as evident for this material. Confocal microscopy, mechanical properties measurements, and molecular spectroscopy are used to further investigate the degradation of both PBO and PPTA.

Kirk D. Rice - One of the best experts on this subject based on the ideXlab platform.

  • Specifying and testing idealized bust surrogates for testing of female stab-resistant Body Armor
    Textile Research Journal, 2015
    Co-Authors: Amanda L. Forster, Emilien Guigues, Michael A. Riley, Kirk D. Rice, Anthony Chan-ou-teung, Aaron M. Forster
    Abstract:

    Manufacturers of stab-resistant Body Armor continually strive to improve the comfort of the Armor wearer and maximize protection. As female officers make up a larger portion of the law enforcement and corrections workplace, Armor manufacturers have begun to offer designs that accommodate contoured Body shapes, such as the female bust region, which results in non-planar Armor. Conventional test methodologies for Body Armor were designed for Armor to be tested flat and do not accommodate contoured Armor. This work reviews the available literature concerning common bust sizes and discusses the research performed to specify bust surrogate size, shape, and materials for testing stab-resistant female Body Armor. Two standard cup sizes, B and D, modeled as a paraboloid with a modified base, are recommended to meet breast volume requirements. Recommendations for manufacture of these surrogates for incorporation into standardized test methods are provided. Instrumented stab testing of these surrogates shows that i...

  • Hydrolytic stability of polybenzobisoxazole and polyterephthalamide Body Armor
    Polymer Degradation and Stability, 2011
    Co-Authors: Amanda L. Forster, Guillaume H.r. Messin, Michael A. Riley, Pierre Pintus, Sylvain H. Petit, Walter J. Rossiter, Joannie W. Chin, Kirk D. Rice
    Abstract:

    Previous work conducted at the National Institute of Standards and Technology (NIST) to investigate the field failures of soft Body Armor containing the material poly(p -phenylene-2,6-benzobisoxazole), or PBO, revealed that this material was susceptible to hydrolysis, and a mechanism of this hydrolysis was proposed. In this work, viscometric estimations of the molar mass of environmentally conditioned PBO are used to support a previously proposed mechanism of PBO hydrolysis. Results with PBO were compared with poly(p-phenylene terephthalamide), or PPTA, which has been used in Body Armor applications for more than 30 years. Losses in tensile strength were found to correspond to a reduction in molar mass for PBO. This indicates that chain scission due to complete hydrolysis is occurring in this material. Similar trends were observed for PPTA, but the relationship between molar mass reduction and losses in tensile strength was not as evident for this material. Confocal microscopy, mechanical properties measurements, and molecular spectroscopy are used to further investigate the degradation of both PBO and PPTA.

  • A detailed investigation of the mechanical properties of polybenzoxazole fibers within soft Body Armor
    Journal of Materials Science, 2009
    Co-Authors: Gale A. Holmes, Michael A. Riley, Walter G. Mcdonough, Kirk D. Rice
    Abstract:

    Using the modified -single fiber test developed by Holmes and colleagues (J Appl Polym 2008 ), a detailed analysis of fibers extracted from soft Body Armor comprised of polybenzoxazole (PBO) fibers was performed. The data indicate that hydrolytic degradation of these ballistic fibers is accompanied by degradation associated with folding (or fatigue-induced degradation) and an undefined degradation mechanism associated with vest use that appears to target the horizontal yarns of the alternating 0°/90° woven layers. These additional failure mechanisms have the potential to create localized regions in the PBO soft Body Armor which are significantly lower than the homogeneous degradation expected from uniform hydrolysis. Results also indicate that the absence of ballistic penetrations in the initial study conducted at the National Institute of Standards and Technology may be associated with using the properties of the fibers from the back panel of a compromised vest as representative of the properties in the front panel that was penetrated. Analysis of a field return vest showed the front panel to be significantly more degraded than the back panel.

Gong Zheng - One of the best experts on this subject based on the ideXlab platform.

  • Structural design of a 3-D printed stab resistant Body Armor
    Rapid Prototyping Journal, 2019
    Co-Authors: Gong Zheng, Xinming Qian, Mengqi Yuan
    Abstract:

    Stab-resistant Body Armor (SRBA) can protect the human Body from injury as a result of stabbing by sharp projectiles. However, in its current design SRBA, it has not been widely adopted for use, because of its weight and poor flexibility. Herein, this paper aims to detail a new type of SRBA that is inspired by the Armor plating of mammals and is fabricated using laser sintering (LS) technology.,This new type of SRBA was fabricated using LS technology. The laser sintered SRBA was subjected to a stab resistance performance test that conformed to the GA 68-2008 Chinese National Standard. The stab resistance response of the novel structured, stab resistance test plates in this study was analyzed using the using the AUTODYN explicit module in ANSYS-Workbench.,The structure of the novel stab resistance plate was designed and the optimum structural parameters were tested, discussed and achieved. The mechanism of dissipation of the impact energy by the pyramidal structures of the novel SRBA was studied, and it was found that this structure dispersed the kinetic energy of the knife and minimized the structural damage to the plate. Interlinks inspired by the pangolin hierarchy structure were designed and used to fabricate a large piece of laser sintered Body Armor.,High-performance laser sintered stab resistance plate was produced via the material and structure studies, which could reduce 40 per cent weight on the stab resistance Body Armor and increase the wearability.

  • The application of PA/CF in stab resistance Body Armor
    IOP Conference Series: Materials Science and Engineering, 2017
    Co-Authors: Mengqi Yuan, Gong Zheng, Ying Liu, Xinming Qian
    Abstract:

    Stab resistance Body Armor (SRBA) is an essential defensive equipment to protect human Body against injuries from stabbing. The conventional SRBAs shared low wearing frequency since they are heavy and poor in flexibility. This paper designed a structured stab-resistance plate using the model of crocodile Armor and manufactured using 3D printing technology-laser sintering (LS). CF(Carbon fiber) was applied to enhance the stab resistance properties of SRBA. The effects of the material and structure were analysed through the stab resistance property tests based on the national standard GA68-2008. It is found that the stab resistance property of flat plates sintered by PA powder and PA/CF are both weaker than that of the structured plate. The penetrating depth of PA/CF structured plate is significantly 2-mm-less than the pure PA structured plate. The SEM observations confirmed the conclusion that addition of the CF largely improved the plate stab resistance property. Moreover, using PA/CF structured plate to produce the stab resistance Body Armor would result in a weight reduction by about 30-40% as compared to the existing SRBA that was made up of metal plates, which could largely reduce the wearer physical burden and improve the wearing frequency.

Dan Yang - One of the best experts on this subject based on the ideXlab platform.

  • multi layer pattern creation for seamless front female Body Armor panel using angle interlock woven fabrics
    Textile Research Journal, 2017
    Co-Authors: Dan Yang, Xiaogang Chen
    Abstract:

    Angle-interlock woven fabric offers an option for making female Body Armor as it can form integrally the required dome shapes because of its extraordinary moldability and satisfactory ballistic per...

  • use of 3d angle interlock woven fabric for seamless female Body Armor part 1 ballistic evaluation
    Textile Research Journal, 2010
    Co-Authors: Xiaogang Chen, Dan Yang
    Abstract:

    In contrast to making male Body Armor, manufacturers of Body Armor encounter problems in design and manufacture of female Body Armor because of the curvaceous Body shape of females. The traditional cut-and-sew method could be used to form the dome shape to accommodate the bust area but it gives rise to weakness at the seams against projectile impact. Fabric folding has been another way to form the domes but it also leads to reduced impact performance and wearing discomfort. In this paper, angle-interlock woven fabrics are proposed as an alternative to the conventional plain woven fabrics in making female Body Armor due to their advantages in moldability without the need of cutting or folding and ease in manufacture. However, it is vital that the angle-interlock fabrics satisfy the ballistic requirements before being employed for the Body Armor application. Part 1 of this paper reports on an investigation on the ballistic performance of angle-interlock fabrics. It has been found that the angle-interlock fabric is not less than the conventional fabric constructions used for Body Armor against ballistic impact. Based on the employment of the angle-interlock fabric, Part 2 presents the mathematical modeling of molding of angle-interlock fabrics to form the front panel of female Body Armor, which would lead to quick creation of female Body Armor based on the input of the Body and bust sizes.

  • use of three dimensional angle interlock woven fabric for seamless female Body Armor part ii mathematical modeling
    Textile Research Journal, 2010
    Co-Authors: Xiaogang Chen, Dan Yang
    Abstract:

    Angle-interlock woven fabric off the potential to make female Body Armor as it can form integrally the required dome shape without cutting or molding because of its extraordinary moldability. In Part I of this paper, ballistic impact testing proved that the angle interlock fabrics provide no less ballistic performance than other commercially used fabrics according to the National Institute of Justice (NIJ) standard. Based on the extraordinary moldability and the satisfactory ballistic performance, Part II presents a mathematical model to determine the pattern geometry for the front panel of female Body Armor. The raised bust area was divided into seven different parts for the modeling, using the simplest surfaces possible. This mathematical model takes the Body size and bra size as the input, and the output is the profile of the front pattern of the female Body Armor. This work enables the speedy creation of the front pattern of female Body Armor, and more importantly a novel approach for making seamless female Body Armor with satisfactory ballistic performance.