Investigation of material deformation mechanism in double side incremental sheet forming

Double side incremental forming (DSIF) is an emerging technology in incremental sheet forming (ISF) in recent years. By employing two forming tools at each side of the sheet, the DSIF process can provide additional process flexibility, comparing to the conventional single point incremental forming (SPIF) process, therefore to produce complex geometries without the need of using a backing plate or supporting die. Although this process has been proposed for years, there is only limited research on this process and there are still many unanswered open questions about this process. Using a newly developed ISF machine, the DSIF process is investigated in this work. Focusing on the fundamental aspects of material deformation and fracture mechanism, this paper aims to improve the understanding of the DSIF process. Two key process parameters considered in this study include the supporting force and relative position between master and slave tools. The material deformation, the final thickness distribution as well as the formability under varying conditions of these two process variables are investigated. An analytical model was developed to evaluate the stress state in the deformation zone. Using the developed model, an explicit relationship between the stress state and key process parameters was established and a drop of stress triaxiality was observed in the double contact zone, which explains the enhanced formability in the DSIF process. Based on the analytical and experimental investigation, the advancements and challenges of the DSIF process are discussed with a few conclusions drawn for future research

Therapeutics effects of inhaled magnesium sulfate combined with adrenergic beta-2 agonist on children with acute asthma: Systematic review and meta-analysis.

AIM: To review the evidence on the effectiveness of inhaled magnesium sulfate (MgSO4) combined with beta-2 (B2) agonist as compared to inhaled B2 agonist alone in treating pediatric patients with moderate to severe asthma attacks METHODS: The search was conducted on five electronic databases namely the Cochrane Central Register of Controlled Trials (CENTRAL), Medline, PubMed, Science Direct, and Google Scholar. RESULTS: Eight trials were included in the review. All studies involved a total of 1585 children aged 2-17 years with moderate to severe asthma attacks. The risk of bias was assessed using the Cochrane risk-of-bias tool for randomized trials. Three studies that assessed the effect of inhaled MgSO4 as adjunctive therapy on vital signs revealed no effect of inhaled MgSO4 on vital signs (SMD -0.11, 95% CI 0.27-0.04, p = 0.16, I2 = 68%). Two studies that assessed the effect of inhaled MgSO4 as adjunctive therapy on asthma severity score (ASS) revealed no effect of inhaled MgSO4 on ASS (SMD 0.22, 95% CI 0.01-0.44, Z = 2.01, p = 0.04, I2 = 88%). Two studies that assessed the effect of inhaled MgSO4 as adjunctive therapy on peak expiratory flow rate (PEFR) revealed a large effect of B2 agonist alone on PEFR (SMD 2.02, 95% CI 0.83-3.2, p < 0.001, I2 = 98%). CONCLUSION: This review does not support the use of inhaled MgSO4 as adjunctive therapy to B2 agonist for asthmatic children

Efficient implicit simulation for incremental forming

Single Point Incremental Forming (SPIF) is a displacement controlled process performed on a CNC machine. A clamped blank is deformed by the movement of a small sized tool that follows a prescribed tool path. An extensive overview of the process has been given in [1]. The tool size plays a crucial role in the SPIF process. The small radius of the forming tool concentrates the strain at the zone of deformation in the sheet under the forming tool. The tool has to travel a lengthy forming path all over the blank to introduce the deformation. Numerically, this requires performing thousands of load increments on a relatively fine FE model resulting in enormous computing time. A typical computing time for implicit simulation of a small academic test is measured in by days. The focus of this paper is to efficiently use the implicit time integration method in order to reduce the required computing time for incremental forming implicit simulation drastically