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RISS 인기검색어
- 검색키워드
- 저자 : Naresh Bhatnagar (검색결과 3 건)
- 무료
- 기관 내 무료
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Design and analysis of low velocity impact on thermoplastic hat section with curvilinear profile
Gaur, Kumresh K,Dwivedi, Mayank,Bhatnagar, Naresh Techno-Press 2017 Advances in materials research Vol.6 No.1
A hat section was designed and developed for maximum impact energy absorption and/or transmission under low velocity impact. Towards this, different hat sections, having material properties of thermoplastic, were modeled and investigated numerically using finite element analysis (FEA) in the range of 20-50 J impact energy. In the study it was experienced that the design configuration of hat section with curvilinear profile (HSCP) was excellent in energy attenuation capacity and for even distribution of maximum impact force around and along the hat section under low velocity impact loading. To validate the numerical findings, polypropylene copolymer (Co-PP) HSCP and low density polyethylene (LDPE) HSCP were developed and evaluated experimentally in the said impact energy range. A correlation was established between FEA and experimental test results, thereby, validating a numerical model to predict results for other thermoplastic materials under given range of impact energy. The LDPE HSCP exhibited better performance as compared to Co-PP HSCP in the said range of impact energy. The findings of this study will enable the engineers and technologists to design and develop low velocity impact resistance devices for various applications including devices to protect bone joints.
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Prajesh Nayak,Anup K. Ghosh,Naresh Bhatnagar 한국섬유공학회 2023 Fibers and polymers Vol.24 No.10
Ultra-high molecular weight polyethylene (UHMWPE) acquires excellent properties while possessing poor processability. Blending low molecular weight polyethylene disentangles the molecular chain of UHMWPE and improves its processability, improving fiber productivity. In the present study, UHMWPE and its HDPE-blended fibers were produced by a high-temperature electrospinning process, and the effect of HDPE content on fiber properties was investigated in depth. Analysis of fiber surface morphology revealed the formation of uniformly distributed nano- to microscopic pores/pits, wrinkles, and grooves on the surface of blended fibers, unlike neat UHMWPE fibers containing irregular surface bulges and pits. It suggested that the blending of HDPE affected the surface topography and the thermal and mechanical properties of electrospun fibers. The tensile strength and Young’s modulus of UHMWPE fiber improved by 142 and 102% at a 67:33 mass ratio of UHMWPE and HDPE and by 84 and 132% in the case of a 50:50 composition ratio, respectively.
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Effect of Supersonic Shock Wave Loading on Thin Metallic Sheets: Experimental and Numerical Studies
Khushi Ram,Kartikeya Kartikeya,Hemant Chouhan,Sanjay Prasad,Puneet Mahajan,Naresh Bhatnagar 한국강구조학회 2023 International Journal of Steel Structures Vol.23 No.3
Defence structures are under high threat of blast loading in recent years due to rising terrorist activities. Protection of defence structures against blast conditions has received a huge interest in the past few years. Blast mitigation requires to study the behavior of various metals under supersonic shock loading. An experimental study was carried out using in-house developed shock tube apparatus to understand effect of shock loading on mild steel and aluminum sheets. A limitation of current study is 1-D loading occurring in shock tube which is unlike 3-D loading occurring in a blast event. Experiments reveal that the properties of thin sheets in through-thickness direction plays an essential role in the shock transfer, which affects considerably the failure and final deformed shape of the sheet. The study showed that metallic thin sheets absorbed shock energy via plastic deformation and failed via a tensile failure mode. Results from this study indicate that aluminum sheets and mild steel sheets can offer shock-resistant properties and mitigate more energy via absorption and plastic deformation. Aluminum and mild steel sheets can therefore be used as a face and back sheet for the development of any sandwich composites.
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