Nick H. Duong

Assessment of Microgrooved Cutting Tool in Dry Machining of AISI 1045 Steel

This paper studies the performance of microgrooved cutting tool in dry orthogonal machining of mild steel (AISI 1045 steel) using advantedge finite element simulation. Microgrooves are designed on the rake face of cemented carbide (WC/Co) cutting inserts. The purpose is to examine the effect of microgroove textured tools on machining performance and to compare it with nontextured cutting tools. Specifically, the following groove parameters are examined: groove width, groove depth, and edge distance (the distance from cutting edge to the first groove). Their effects are assessed in terms of the main force, thrust force, and chip–tool contact length. It is found that microgrooved cutting tools generate lower cutting force and thrust force, and consequently lower the energy necessary for machining. The groove width, groove depth, and edge distance all have influence on cutting force in their own ways.

Finite element investigation of friction and wear of microgrooved cutting tool in dry machining of AISI 1045 steel

This article studies the tribological performance of microgrooved cutting tool in dry orthogonal machining of mild steel (AISI 1045 steel) using finite element simulation. The purpose is to examine the effects of microgrooves on friction and wear of the textured tools and to compare it with non-textured cutting tools. For the cemented carbide (WC/Co) cutting inserts, microgrooves are designed on the rake face. Specifically, the following groove parameters are examined: groove width, groove depth, and edge distance (the distance from the cutting edge to the first groove). Their effects are assessed in terms of friction coefficient and wear on the rake face. It is found that microgrooved cutting tools can significantly reduce friction and wear in machining, which is attributed mainly to the reduced chip–tool contact length.

Investigation of Distortion-Induced Web-Gap Cracking in a Seismically Retrofitted Steel Bridge: Repair Measures

AbstractThis paper studies distortion-induced fatigue cracks in a 1960s-era welded plate girder bridge that developed cracks in the web-gap region shortly after completion of a comprehensive seismic retrofit. Finite-element analysis (FEA) and field testing were conducted to investigate the cause of cracking and then to recommend appropriate repair measures for the bridge. The field test results validated the high-stress concentrations in the web-gap region of the bridge that led to fatigue cracking after only a limited number of cycles. FEA results indicated that the high-stress concentrations were principally a result of replacing K-type diaphragms with stiffer cross diaphragms as part of the seismic retrofit. Two conventional repair measures in addition to two innovative repair measures were evaluated. The proposed innovative repair measures focused on ease of installation compared with more conventional options and were found to reduce the distortion-induced stresses well below the constant amplitude f...

Repair Measures for a Seismically Retrofitted Steel Bridge Experiencing Distortion-Induced Fatigue Cracks: Numerical Study

This paper studies distortion-induced fatigue cracks in a 1960’s era design Missouri Department of Transportation (MoDOT) welded plate girder bridge that developed cracks in the web-gap region shortly after completion of a comprehensive seismic retrofit. Finite Element analysis (FEA) was conducted in order to investigate the cause of cracking and to recommend appropriate repair measures for the bridge. The results indicated that the high stress concentrations were principally a result of replacing K-type diaphragms with stiffer cross-diaphragms as part of the seismic retrofit. Two conventional repair measures in addition to two innovative repair measures were evaluated. The first repair strategy provided a positive connection between the connection plate and the girder flange (referred to as the top-angle repair). The second repair created a 203-mm (8-in.) slot where one-sixth of the connection plate depth is cut from the web (slot-repair) resulting in a softening of the web gap.

Numerical Analysis of Tool Performance in Up Milling of Ti-6Al-4V Alloy

Ti-6Al-4V is widely used in industry because of its high strength-to-weight ratio at elevated temperatures, its excellent resistance to fracture and corrosion, and biological properties. However, Ti-6Al-4V is classified as hard-to-cut material because of its high chemical reactivity with most tool materials and its low thermal conductivity that causes high temperature on the tool face. Consequently, prediction of the tool temperature distribution has great significance in predicting tool wear pattern. In this research, Finite Element Method (FEM) is employed to conduct numerical investigation of the effects of cutting conditions (cutting speed, feed/tooth, and axial depth of cut) in corner up milling on temperature of the tool rake face. The tool material used is general carbide and the behavior of the workpiece Ti-6Al-4V is described by using Johnson-Cook plastic model. Because of the computational expense, a separate heat transfer model is built to analyze the heat transfer process after the tooth disengages the workpiece and before it engages the workpiece again to predict change of temperature distribution during this cooling process. This research provides helpful guidance for selecting tool cooling strategies in up milling Ti-6Al-4V alloy.Copyright

Assessment of Restricted Contact Cutting Tool in Dry Machining of AISI 1045 Steel

This paper studies the performance of restricted cutting tool in dry orthogonal machining of mild steel (AISI 1045 steel) using finite element simulations. The rake face of cemented carbide (WC/Co) cutting inserts is designed and the rake face length is shortened. The purpose is to examine the effect of shortened tools on machining performance and to compare it with regular cutting tools. The following restricted tool parameters are examined: length of rake face, alpha angle (the angle between the rake face and the supporting face), and edge radius. Their effects are assessed in terms of the main force, thrust force, and chip-tool contact length. It is found that restricted cutting tools generate lower cutting force and thrust force and consequently lower the energy necessary for machining. The length of rake face, the angle between the rake face and the supporting face, and edge radius all have influence on cutting force in their own ways. The effects of these three parameters on the tool temperature distribution are also investigated.Copyright

Assessment of the Performance of Microbumped Cutting Tool in Machining of AISI 1045 Steel

This paper investigates the performance of microbump textured cutting tool in dry orthogonal machining of mild steel (AISI 1045 steel) using AdvantEdge finite element simulation. Microbumps are designed on the rake face of cemented carbide (WC/Co) cutting inserts. The purpose is to examine the effect of microbump textured tools on machining performance and to compare it with non-textured regular cutting tools. Specifically, the following microbump parameters are examined: microbump width, microbump height, and edge distance (the distance from cutting edge to the first microbump). Their effects are assessed in terms of the main force, thrust force, and chip-tool contact length. It is found that microbump textured cutting tools generate lower cutting force and thrust force and consequently lower the energy consumption for machining. The micobump width, microbump height, and edge distance all have influence on cutting force in their own ways.Copyright