This work addresses the micro- and nano-behaviors in metals through constitutive modeling and experiments. The size effect encountered during nanoindentation experiments, which is known as indentation size effect (ISE), is investigated for metal materials. The ISE is believed to be related with the strain gradient at small indentation depths. Geometrically necessary dislocations (GNDs) are formed in order to accommodate the strain gradient, which results in the increase in the material hardness. The grain boundaries in polycrystalline materials play an important role on the material hardness during nanoindentation experiments as there is a soften-hardening segment in the curve of hardness as a function of the indentation depth. The grain boundaries act as barriers of the movement of dislocations that leads to an increase of the dislocation density. The increasing dislocation density gives the additional increase in material hardness, resulting in the hardening phenomenon. The classical continuum mechanics has to be enhanced with the strain gradient plasticity theory in order to address the ISE. Using the strain gradient plasticity theory, a material intrinsic length scale parameter is incorporated. The length scale bridges the gap between the behaviors in macro-scale and the micro-/nano-scale. The ISE of different materials can be characterized using this length scale parameter. The length scale parameter is determined through the strain plasticity model, the nanoindetation experiments using continuous stiffness measurement (CSM) mode in determining the fitting parameters and the finite element method (FEM) in determining the equivalent plasticity strain in the expression of the length scale. The rate dependency of ISE is investigated and it shows that the hardness increases with the increasing strain rate. The length scales at different strain rates are determined and they decrease with the increasing strain rate, leading to the increase in the hardness. The grain boundary effect on the hardness is verified as there is no hardening-softening phenomenon in single crystalline materials as there is no grain boundary in them. The grain boundary effect is further isolated by using bicrystalline materials. The single grain boundary is investigated through nanoindentation experiments from different distances to the grain boundary. The results show that the hardness increase as the distance decreases, providing a new type of size effect.

published_or_final_version / Computer Science / Master / Master of Philosophy

There has been an increasing amount of emphasis placed on antipoverty programs in the past number of years. Some of these programs are aimed at a particular segment of the population and designed to provide skills for unemployed and/or underemployed people. One such program is found in the Interlake area of Manitoba at Selkirk. Set up in 1969 under the F.R.E.D. Agreement, this program is aimed at Indian and Metis people in the Interlake. The program consists of a training program for carpentry, sheet metal work, painting and design. Park furniture is produced at the plant while the clients are in training. This report evaluates the Selkirk program in terms of the benefits that accrue to the individual trainees. Therefore, the program is evaluated in terms of its own objectives. The evaluation consisted of gathering data related to the program's impact on individual's income, employability and standard of living. In addition, data was also gathered on employment history, trainee satisfaction, family situation and the client's evaluation of the program. The data, upon analysis, illustrated that the program had its largest impact on the increase of material possessions. This was followed by the increase of individual's incomes. Another area of strong impact was that of increased employability. An important point to note is that most of the trainees interviewed (19 of 24) were employed immediately after receiving training. Very few held jobs before entering the program. The clients also identified areas of the training program they considered as needing improvement. These areas identified, in order of importance, included longer training periods, more classroom time, more information and instruction in the use of employment services, closer evaluation of trainees entering the program and a dissatisfaction of training allowances paid. It is important to note that the dissatisfaction of allowances was of least importance to clients.

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