title: Simulation of Titanium and Titanium Alloy Powder Compact Forging

authors: Zhang, Zhibo

subjects: Titanium

abstract: Simulation can be divided into two types: physical simulation and interactive numerical simulation. Physical simulation depends on testing smaller or cheaper samples rather than real objects to simplify models; Interactive simulation, which is also been called numerical simulation is depending on mathematical models and computer program to get the detailed results of the model. In this thesis, 48 compression test samples of sintered powder compacts of pure titanium (HDH) and Ti-6Al-4V were tested by using Gleeble 1500 thermal simulation testing machine. The height reduction of all samples was set as 70% and the other experiment conditions were set as three different temperatures and two strain rates. The stress-strain curves of all samples have been collected in the computer which could be considered as basic for the 3D-FEM simulation. Metal plastic forming is a coupled thermo-stress process in which the workpiece is loaded and restricted in some boundary conditions which include force, temperature, velocity, geometry, friction and so on. Thus, the scientific objective of plastic forming simulation is to be able to predict and control these phenomenon and transformation.The upsetting of powder compacts of pure titanium (HDH) and Ti-6Al-4V (GA) was studied in this thesis based on theoretical and physical models and numerical simulation. Based on the constituent model in ABAQUS and the results of thermo-simulation, the upsetting of 3D-FEM model was built which involved heat transfer, deformation and densification. The temperature field, Mises stress field, strain rate field, strain field and relative density field of pure titanium (HDH) and Ti-6Al-4V (GA) powder compacts were attained. Comparing the density distribution of the metallographic phases in optical microscope with the results of simulation, basically, the experimental results are in general agreement with the results of simulation.

text: Simulation of Titanium and Titanium Alloy Powder Compact Forging Simulation can be divided into two types: physical simulation and interactive numerical simulation. Physical simulation depends on testing smaller or cheaper samples rather than real objects to simplify models; Interactive simulation, which is also been called numerical simulation is depending on mathematical models and computer program to get the detailed results of the model. In this thesis, 48 compression test samples of sintered powder compacts of pure titanium (HDH) and Ti-6Al-4V were tested by using Gleeble 1500 thermal simulation testing machine. The height reduction of all samples was set as 70% and the other experiment conditions were set as three different temperatures and two strain rates. The stress-strain curves of all samples have been collected in the computer which could be considered as basic for the 3D-FEM simulation. Metal plastic forming is a coupled thermo-stress process in which the workpiece is loaded and restricted in some boundary conditions which include force, temperature, velocity, geometry, friction and so on. Thus, the scientific objective of plastic forming simulation is to be able to predict and control these phenomenon and transformation.The upsetting of powder compacts of pure titanium (HDH) and Ti-6Al-4V (GA) was studied in this thesis based on theoretical and physical models and numerical simulation. Based on the constituent model in ABAQUS and the results of thermo-simulation, the upsetting of 3D-FEM model was built which involved heat transfer, deformation and densification. The temperature field, Mises stress field, strain rate field, strain field and relative density field of pure titanium (HDH) and Ti-6Al-4V (GA) powder compacts were attained. Comparing the density distribution of the metallographic phases in optical microscope with the results of simulation, basically, the experimental results are in general agreement with the results of simulation.

year: 2011

title: The prevalence and impairment effects of drugged driving in New Zealand

authors: Starkey, Nicola J.

subjects: attitudes, drugged driving, incidence, medication, prevalence, toxicology

abstract: The purpose of the research was to establish a quantitative picture of the type and the extent of drugged driving in New Zealand and investigate the level of driving impairment produced by the most commonly used drugs, both legal and illegal. A stratified telephone survey (n=2,000) and internet survey (n=434) were conducted to explore the extent of drugged driving. Other than alcohol, the drugs most commonly taken prior to driving were strong opioid-based painkillers, antidepressant medication, anti-nausea medication, cannabis and anti-anxiety medication. A large proportion of drivers also reported taking combinations of different drugs prior to driving. Of the most commonly taken drugs, cannabis, opioid-based painkillers and benzodiazepines (typically used to treat anxiety or insomnia) have been associated with increased crash and driving-related impairment. The combination of drugs and alcohol leads to significantly higher crash risk and driving-related impairments. Between 25% and 50% of drivers who reported taking drugs admitted ‘drugged driving’ more than once a week over the last 12 months; for prescription drugs this most frequently occurred in the morning, while for illegal drugs this was typically in the evening.

text: The prevalence and impairment effects of drugged driving in New Zealand The purpose of the research was to establish a quantitative picture of the type and the extent of drugged driving in New Zealand and investigate the level of driving impairment produced by the most commonly used drugs, both legal and illegal. A stratified telephone survey (n=2,000) and internet survey (n=434) were conducted to explore the extent of drugged driving. Other than alcohol, the drugs most commonly taken prior to driving were strong opioid-based painkillers, antidepressant medication, anti-nausea medication, cannabis and anti-anxiety medication. A large proportion of drivers also reported taking combinations of different drugs prior to driving. Of the most commonly taken drugs, cannabis, opioid-based painkillers and benzodiazepines (typically used to treat anxiety or insomnia) have been associated with increased crash and driving-related impairment. The combination of drugs and alcohol leads to significantly higher crash risk and driving-related impairments. Between 25% and 50% of drivers who reported taking drugs admitted ‘drugged driving’ more than once a week over the last 12 months; for prescription drugs this most frequently occurred in the morning, while for illegal drugs this was typically in the evening.

year: 2017

title: Making sense of Te Whāriki a te Kōhanga Reo through toi Māori: A whānau approach

authors: McMillan, Hoana

abstract: The involvement of whānau in the teaching and learning process is important at every juncture of a child’s educational journey. Rich understanding of the curriculum enables whānau to make deep and meaningful contributions to discussions about their child’s development. It also presents an interesting challenge for educational settings to create opportunities for whānau to increase their knowledge of the curriculum. This article outlines the benefits of a toi Māori approach to support whānau understanding.

text: Making sense of Te Whāriki a te Kōhanga Reo through toi Māori: A whānau approach The involvement of whānau in the teaching and learning process is important at every juncture of a child’s educational journey. Rich understanding of the curriculum enables whānau to make deep and meaningful contributions to discussions about their child’s development. It also presents an interesting challenge for educational settings to create opportunities for whānau to increase their knowledge of the curriculum. This article outlines the benefits of a toi Māori approach to support whānau understanding.

year: 2023