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Study of optimal weld design for arc plug welding of advanced high strength steels
ARUN LALACHAN,SIVA PRASAD MURUGAN,김경영,신지영,김두영,공호영,박영도 대한용접·접합학회 2021 대한용접학회 특별강연 및 학술발표대회 개요집 Vol.2021 No.11
The incorporation of Advanced high strength steels (AHSS) into the automotive architecture have led to reduction of the vehicle weight and improve the crash worthiness. Majorly Resistance spot welding and laser welding have been employed for joining car-body joining. However, these joining techniques poses an issue of reachability in chassis part. To resolve this issue, arc plug welding was introduced as a novel method. The transition of the welding process to arc welding process requires knowledge of the weldability of the arc plug welding. In this study, an experimental method for the selection of the optimal plug welding shape in 1180MPa AHSS with the equivalent effective weld area to the 6.0mm nugget diameter in spot welds was performed. The arc plug welding was performed with 3 different plug hole shapes namely circle plug (6φ) and elliptical plug (4x9 and 3x12mm) to define the optimum weld shape design for plug welding. The optimized welded sample were subjected for mechanical characterization like hardness and Tensile shear performance. The experimental results confirm that the Elliptical plug welding of 4x9 hole showed 68% increase in TSS performance with the low strength wire (ER70S-6) than the resistance spot welding counterparts and poses a possible replacement for securing weld robustness.
ARUN LALACHAN,SIVA PRASAD MURUGAN,KIM KYUNG-YOUNG(김경영),SHIN JI-YOUNG(신지영),DOOYOUNG KIM(김두영),GONG HO-YOUNG(공호영),YEONG DO PARK(박영도) 대한용접·접합학회 2021 대한용접학회 특별강연 및 학술발표대회 개요집 Vol.2021 No.5
Efforts to reduce the vehicle weight and improve the crash performance have led to the increased application of advanced high strength steels (AHSS) into the automotive architecture. Although resistance spot welding and laser welding are mainly used for joining thin sheets in the car body. these joining methods poses a problem of reachability in chassis part. To overcome this issue, arc plug welds are invented as a novel method for joining steel sheets in chassis part. These shift in joining procedure to arc plug welds, consequently propelled the need for the understanding of the plug weldability of various steel sheets. In this study, to investigate the plug weldability, a comparative evaluation of six steel sheets ranging from 440MPa to 1500MPa with similar thickness of 1.0 mm has been done by using ER110S wire in 8:2 Ar-CO2 atmosphere with a circular hole of 6.0 mm diameter. The static tensile shear strength and microstructure of these arc plug welds with similar effective interfacial weld diameter of 6.0 mm are detailed. It was found that the AHSS consistently achieved high tensile shear strength compared to the conventional steel grades. The differences in failure mode are attributed due to the HAZ softening and weld metal hardness.
ARUN LALACHAN,SIVA PRASAD MURUGAN,김경영,신지영,김두영,공호영,박영도 대한용접·접합학회 2021 대한용접학회 특별강연 및 학술발표대회 개요집 Vol.2021 No.5
Efforts to reduce the vehicle weight and improve the crash performance have led to the increased application of advanced high strength steels (AHSS) into the automotive architecture. Although resistance spot welding and laser welding are mainly used for joining thin sheets in the car body. However, the joining methods poses a problem of reachability in chassis part. To overcome this issue, arc plug welds are invented as a novel method for joining steel sheets in chassis part. To address this shift in joining procedure to arc plug welds, consequently propelled the need to the understanding of the plug weldability of various steel sheets. In this study, to investigate the plug weldability, a comparative evaluation of six steel sheets ranging from 440MPa to 1500MPa with similar thickness of 1.0 mm has been done by using ER110S wire in 8:2Ar CO2 atmosphere with a hole of 6 mm. The mechanical properties and microstructure of these arc plug welds with similar effective interfacial weld diameter of 6mm are detailed. It was found that the AHSS consistently achieved high tensile shear strength compared to the conventional steel grades. The differences in failure mode are attributed due to the HAZ softening and weld metal hardness.
Tiwari Arun Kumar,Gupta Pushpraj S,Prasad Mahesh,Malairajan Paraman 대한약침학회 2022 Journal of pharmacopuncture Vol.25 No.4
Objectives: Hyperlipidemia (HL) is a major cause of ischemic heart diseases. The size-limiting effect of ischemic preconditioning (IPC), a cardioprotective phenomenon, is reduced in HL, possibly because of the opening of the mitochondrial permeability transition pore (MPTP). The objective of this study is to see what effect pretreatment with Inula racemosa Hook root extract (IrA) had on IPC-mediated cardioprotection on HL Wistar rat hearts. An isolated rat heart was mounted on the Langendorff heart array, and then ischemia reperfusion (I/R) and IPC cycles were performed. Atractyloside (Atr) is an MPTP opener. Methods: The animals were divided into ten groups, each consisting of six rats (n = 6), to investigate the modulation of I. racemosa Hook extract on cardioprotection by IPC in HL hearts: Sham control, I/R Control, IPC control, I/R + HL, I/R + IrA + HL, IPC + HL, IPC + NS + HL, IPC + IrA+ HL, IPC + Atr + oxidative stress, mitochondrial function, integrity, and hemodynamic parameters are evaluated for each group. Results: The present experimental data show that pretreatment with IrA reduced the LDH, CK-MB, size of myocardial infarction, content of cardiac collagen, and ventricular fibrillation in all groups of HL rat hearts. This pretreatment also reduced the oxidative stress and mitochondrial dysfunction. Inhibition of MPTP opening by Atr diminished the effect of IrA on IPC-mediated cardioprotection in HL rats. Conclusion: The study findings indicate that pretreatment with IrA e restores IPC-mediated cardioprotection in HL rats by inhibiting the MPTP opening.
Theerthagiri Jayaraman,Arun Prasad Murthy,Venugopal Elakkiya,Sivaraman Chandrasekaran,Palaniyandy Nithyadharseni,Ziyauddin Khan,Raja Arumugam Senthil,Ravishanker,Mitty Raghavender,Parasuraman Kuppusam 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.64 No.-
Nanostructured carbon based materials with unique and tunable properties make them to be utilized forvarious applications in different forms especially for energy and environmental applications. Carbon is adistinctive chemical element which has superior properties such as porous structure, low cost, resistanceto basic and acidic conditions, easy accessibility, low density, good recycling properties, more abundantand ability to combine with other chemical elements in different ways. In this review, we have criticallyassessed the recent developments in carbon based heterostructures for their applications in energy andenvironment. Special consideration has been paid on the applications in dye-sensitized solar cells,hydrogen evolution reaction, oxygen evolution reaction, Li-ion battery, supercapacitor, photocatalysis forthe degradation of organic pollutants, electrochemical/bio sensors and biomedical applications. Finally,the challenges and future developments of carbon based heterostructures for applications in energy andenvironment are also outlined.
Peat stabilization using cement, polypropylene and steel fibres
Kalantari, Behzad,Prasad, Arun,Huat, Bujang B.K. Techno-Press 2010 Geomechanics & engineering Vol.2 No.4
This article describes a laboratory research on stabilizing tropical peat using ordinary Portland cement (OPC) as a binding agent, and polypropylene and steel fibres as chemically inert additives. California bearing ratio (CBR) and unconfined compressive strength (UCS) tests were carried out to evaluate the increase in the strength of the stabilized samples compacted at their optimum moisture contents and air cured for up to 90 days. The results show that the UCS values of stabilized peat samples increased by as high as 748.8% by using OPC (5%), polypropylene fibres (0.15%), and steel fibres (2%). The CBR values of the samples stabilized with OPC (5%), polypropylene fibres (0.15%), and steel fibres (4%) showed an increase of as high as 122.7%. The stabilized samples showed a shrinkage in volume upon air curing and this shrinkage was measured by an index called, volume shrinkage index (VSI). The highest VSI recorded was 36.19% for peat without any additives; and the minimum was 0% for the sample containing 30% OPC, 0.15% polypropylene fibres and 2% steel fibres. The technique of stabilizing peat with OPC, polypropylene and fibres, coupled with air curing, appears to be cost-effective compared with other frequently used techniques.
저항 점 용접 Current Profiling에 따른 Heat Balance 및 인장응력 변화와 LME 균열과의 상관성 연구
김지웅,Siva prasad Murugan,Arun lalachan,김준수,육완,이창용,박영도 대한용접·접합학회 2021 대한용접학회 특별강연 및 학술발표대회 개요집 Vol.2021 No.5
아연 도금된 강판을 저항 점용접 시, 용접부 표면에서 시작되는 liquid metal embrittlement (LME) 현상이 관찰되고 있다. LME 균열은 높은 용접 입열에 의해 형성된 용융 아연과 인장 응력이 동시에 만족되는 경우 발생한다. 액상 아연은 강(steel)의 결정립계로 침투하여 결정립계의 결합력을 약화시키므로, 용접부 표면에 균열을 형성한다. 아연에 의한 LME 균열은 인장응력, 액상 아연, LME에 민감한 강(steel)의 미세조직과 같은 3가지 주요 인자에 의해 발생된다. 최근 까지도 LME crack을 저감 하기 위해 도금층 제어 및 전극 형상 설계 등 다양한 연구들이 활발하게 진행되고 있다. 특히, 저항 점용접 전류 파형 설계(down slope)를 통해 판재 표면에 액상 아연이 노출되는 시간과 인장 응력의 급격한 상승을 제어하여 LME 균열의 크기가 감소한 연구 결과가 보고되었으나, 인장 응력이 제어된 원인과 LME 균열과 인장 응력간 상관 관계 등에 대한 설명이 부족하였다. 따라서, 본 연구에서는 3가지의 다른 전류 파형을 적용하여 전류 파형 별 인장 응력 거동 차이와 원인 분석, 그리고 저항 점 용접시 전극과 판재가 접촉한 영역과 접촉하지 않은 영역 사이의 열적 비평형상태가 인장 응력에 미치는 영향 등을 분석하였다. 본 연구의 목표를 달성하고자 SORPAS® 시뮬레이션 프로그램을 사용하였으며, 이를 통해 전류 통전 시, 전극과 판재간 접촉은 판재 표면을 냉각시키며, 접촉 면적 증가는 판재 표면에 급격한 냉각효과를 발생시키므로, 판재 표면의 열적 불균형 상태를 야기시킨다. 이 열적 불균형 상태가 판재 표면부의 인장 응력을 유발시키는 것으로 사료되며, 전류 파형에 따른 열적 불균형 상태와 인장 응력 거동에 대한 차이가 관찰되었다.