Densification simulation of compacted Al powders using multi-particle finite element method

The powder compaction simulations were performed to demonstrate deformation behavior of particles and estimate the effect of different punch speeds and particle diameters on the relative density of powder by a multi-particle finite element model(MPFEM). Individual particle discretized with a finite element mesh allows for a full description of the contact mechanics. In order to verify the reliability of compaction simulation by MPFEM, the compaction tests of porous aluminum with average particle size of 20 μm and 3 μm were performed at different ram speeds of 5, 15, 30 and 60 mm/min by MTS servo-hydraulic tester. The results show that the slow ram speed is of great advantage for powder densification in low compaction force due to sufficient particle rearrangement and compaction force increases with decrease in average particle size of aluminum.

FEA technique of hot plate forming process using cell-typed die with cooling device

Hot plate forming using a cell-typed die is a process for forming a large thick plate with a spherical shape for the manufacture of a large spherical LNG tank.Cell-typed upper and lower dies made of a framework of steel plates fitted to make a grid pattern are used in this process,and an air-cooling device is separately installed inside the lower die.A finite element analysis (FEA) technique was developed,which included hot forming,air flow,cooling and thermal deformation analysis for the hot plate forming process using the cell-typed die.Further,the convective and interface heat transfer coefficients were used to reproduce analytically the effects of the cooling device in the hot plate forming analysis.A small-scale model test of the process was conducted to verify the FEA technique.The analysis results show that the curvature of the final plate agrees well with that of the designed experiment within a maximum relative error of 0.03% at the corner of the plate.

Effects of elastic-plastic properties of materials on residual indentation impressions in nano-indentation using sharp indenter

One of the primary features of nano-indentation technique is that the contact area induced by an indenter is indirectly measured by a relationship between the penetration depth and the known geometry of the indenter.However,this indirect measurement occasionally leads to inaccurate properties of the indented material.The objective of this study is to investigate the effects of E/σr and the strain hardening exponents n of materials on the behaviors of pile-up and sink-in in nano-indentation and to predict n values of materials from the residual indentation impressions.The relations between the residual indentation profile and n value of the indented material were identified by dimensional analysis.Also,they were numerically formulated using FE analysis of nano-indentation for 140 different combinations of elastic-plastic parameters such as E,σy and n.The parameters of hrp/hm,herp/hm,Rr/hm and HO&P/Hreal were introduced as various dimensionless parameters to represent and quantify the residual indentation profile after indentation.They were subsequently characterized as dimensionless functions using n and E/σr values.Finally,the validity of these functions was verified through 3D FE analysis of nano-indentation for Al 6061-T6 and AISI 1010 materials.

Quality of life outcomes including neuropathy-associated scale from a phase II,multicenter,randomized trial of eribulin plus gemcitabine versus paclitaxel plus gemcitabine as first-line chemotherapy for HER2-negative metastatic breast cancer:Korean Cancer Study Group Trial(KCSG BR13-11)

Background: A phase II clinical trial of the comparison between eribulin plus gemcitabine (EG) and paclitaxel plus gemcitabine (PG) as first-line chemotherapy for patients with metastatic breast cancer (MBC) found that the EG regimen was less neurotoxic, but was similar in efficacy to the PG regimen. In the present study, we analyzed functional assessment of cancer therapy-taxane (FACT-Taxane) questionnaires from patients in this clinical trial to determine their quality of life (QoL). Methods: QoL was assessed using the Korean version of the FACT-Taxane questionnaires. After baseline assessment, QoL was assessed every 2 cycles for 12 cycles and every 3 cycles thereafter. The linear mixed model was used to evaluate the difference in QoL between the EG and PG arms. Results: Of the 118 enrolled patients, 117 responded to the FACT-Taxane questionnaires at baseline, 1 in the PG arm did not. Baseline QoL scores were not different between the EG and PG arms. During treatment, taxane subscale scores were significantly higher in the PG arm than in the EG arm after 2-13 cycles of chemotherapy (all P < 0.05), except for the 11th cycle. Neuropathy-specific analysis showed that patients in the PG arm had earlier and more severe neuropathic symptoms than those in the EG arm (P < 0.001). Conclusions: In our QoL analysis, the EG regimen delayed and decreased neuropathy as compared with the PG regimen. Therefore, eribulin would be a reasonable substitute for paclitaxel as first-line chemotherapy for MBC.