A finite element simulation of micro-mechanical frictional behaviour in metal forming

Friction is a critical factor for sheet metal forming (SMF). The Coulomb friction model is usually used in most finite element (FE) simulation for SMF. However, friction is a function of the local contact deformation conditions, such as local pressure, roughness and relative velocity. Frictional behaviour between contact surfaces can be based on three cases: boundary, hydrodynamic and mixed lubrication. In our microscopic friction model based on the finite element method (FEM), the case of dry contact between sheet and tool has been considered. In the view of microscopic geometry, roughness depends upon amplitude and wavelength of surface asperities of sheet and tool. The mean pressure applied on the surface differs from the pressure over the actual contact area. The effect of roughness (microscopic geometric condition) and relative speed of contact surfaces on friction coefficient was examined in the FE model for the microscopic friction behaviour. The analysis was performed using an explicit FE formulation. In this study, it was found that the roughness of deformable sheet decreases during sliding and the coefficient of friction increases with increasing roughness of contact surfaces. Also, the coefficient of friction increases with the increase of relative velocity and adhesive friction coefficient between contact surfaces.

Micro-credit programs and land distribution: a note

"Micro-credit" has come to refer to a popular extension strategy---usually in the agricultural sector---whereby a government or NGO extends credit at favorable rates to poorer borrowers, with repayment being supported by some kind of mortgage on the borrower's social capital. In the commonest case, eligibility is determined by the borrower's wealth, as indexed by his/her landholding. This note shows that, with an imperfect land market, the response to such a program will be to fragment landholdings which are smaller than a certain threshold, while larger holdings remain unaffected. Thus the pattern of landholding will tend to become more polarized.

Micro finance programs: caring for those missed by formal social protection mechanism

In line with the current global trend of economic and social restructuring, it has become essential to address the issue of poverty and social protection for the poorer segment of the population who are not covered by formal social protection mechanisms. Micro finance institutions (MFIs) in developing countries have been working towards poverty alleviation and enhancing social protection for the last few decades. MFI’s provision of financial assistance to the poor has been instrumental in improving the overall quality of the impoverished. Based on an in-depth qualitative study conducted across three different types of NGOs (Non Governmental Organization) in the Philippines, this study found a relationship between micro finance programs and improved social protection. The study reveals that MFIs have the ability to make a positive impact on areas such as entrepreneurship, education, housing, job security and income generation.

Reassessing Grameen Bank's micro credit programme for poverty alleviation in bangladesh : a new perspective

Rural finance has been a mltior policy in alleviating poverty in developing countries. Of specific interest are the micro credit programmes that target the poorest segment of the population. Despite some successes in particular settings, the efficacy of micro credit programmes has been a mltior concern in recent years. This paper evaluates the success of the Grameen Bank, the premier micro credit provider in rural areas in Bangladesh in the context of contemporary development philosophies. Only a few studies have evaluated the performance of the Grameen Bank from a poverty alleviation perspective. Many have evaluated the efficiency of the Grameen Bank's micro credit programmes using attributes such as the repayment rate. In this paper, we add a new dimension to the literature by arguing that if poverty alleviation is the ultimate objective, then the bank's micro credit programme should be assessed from the borrowers' perspective. Rural credit should be conceptualised not as just an input to production but as a mechanism for rural transformation. Our analysis reveals that while Grameen Bank is an efficient provider of micro credit in rural Bangladesh, its programmes fall short of achieving poverty alleviation for a multitude of borrowers and reshaping the process is hence a critical imperative.

E-business security management for Australian micro SMEs - a case study

Small and Medium Business Enterprises (SMEs) make a significant contribution to the economic viability of the Australian economy. The benefits of performing business in an on-line environment has been realised by Australian SMEs as the use of the Internet for performing business activities both with consumers and other businesses continues to increase. The findings of an empirical study and other evidence available indicate the uptake and advancement of performing e-business activities shall be dependent on two key complementary elements: first, the ability of Australian SMEs to secure their e-business systems; and second, the availability of an approach to recommend a practical e-business security management strategy. This paper presents the results of a case study which applied a previously developed methodology to a micro SME e-business system. The purpose was to validate the ability of the Australian Small to Medium Enterprise E-business Security Methodology (ASME-EBSM) to provide an effective security management strategy for Australian SMEs. The outcome demonstrated that this approach was both feasible and realistic for providing recommendations to secure the e-business activities performed and to protect the micro SME e-business system.

The ethical outlook of micro business operators

This paper reports the findings of an investigation into the ethical outlook of micro business operators. The study was conducted in Australia and is the first such examination of ethical perspectives in this segment of the business population. Micro business is internationally recognizable, economically significant, and strongly entrepreneurial, and it has a high level of control over the values it enacts. The study indicates that ethical considerations are important to Australian micro business operators. While no one single ethical perspective was dominant, nonreligious beliefs and principles were found to be the most important determinant of their ethical values. Some variation was discovered in operator attitudes based on age, gender, and education.

Numerical modeling of interactions between a macro-crack and a cluster of micro-defects

The interactions between a macro-crack and a cluster of micro-defects are studied numerically by using a series of special finite elements each containing a defect. These special finite elements, which contain defects such as holes, cracks, and inhomogeneities, are developed based on the hybrid displacement, complex potential and conformal mapping techniques. These hybrid-type elements can be used together with the conventional finite elements without any difficulty. Thus, simple finite element models can be devised to study the interactions between a macro-crack and a cluster of micro-defects. In this paper, the mathematical and finite element modeling procedures for the study of the above-mentioned problems are presented.

Micro-porous nickel produced by powder metallurgy

Micro-porous nickel (Ni) with an open cell structure was fabricated by a special powder metallurgical process, which includes the adding of a space-holding material. The average pore size of the micro-porous Ni samples approximated 30 μm and 150 μm, and the porosity ranged from 60 % to 80 %. The porous characteristics of the Ni samples were observed using scanning electron microscopy (SEM) and the mechanical properties were evaluated using compressive tests. For comparison, porous Ni samples with a macro-porous structure prepared by both powder metallurgy
(pore size 800 μm) and the traditional chemical vapour deposition (CVD) method (pore size 1300 μm) were also presented. Results indicated that the porous Ni samples with a micro-porous structure exhibited different deformation behaviour and dramatically increased mechanical properties,
compared to those of the macro-porous Ni samples.

Mechanical properties of micro-porous metals produced by space-holding sintering

Micro-porous nickel foams with an open cell structure were fabricated by the space-holding sintering. The average pore size of the micro-porous nickel specimens ranged from 30 μm to 150 μm, and the porosity ranged from 60 % to 80 %. The porous characteristics of the nickel specimens were observed using scanning electron microscopy (SEM). The mechanical properties were studied using compressive tests. For comparison, macro-porous nickel foams prepared by the chemical vapour deposition method with pore sizes of 800 μm and 1300 μm and porosity of 95 % were also presented. Results indicated that the ratio value of 6 and higher for the specimen length to cell size (L/d) is satisfying for obtaining stable compressive properties. The micro-porous nickel specimens exhibited different deformation behaviour and dramatically increased mechanical properties, compared to those of the macro-porous nickel specimens.

Finite element simulation of deformation processes of micro-components

The aim of this paper is to improve the understanding of deformation of micro medical needle and thread during assembly and then to develop an economical and flexible deformation method. Therefore, the swaging process is computationally simulated with the finite element method in this paper. A commercially available explicit nonlinear finite element analysis code, LS-Dyna, is used to model the 3-D deformation and contact problem. As the firmness of the assembly on the needle depends on the contact force and friction, the contact and the slide between the needle and thread are taken into account in the simulation. The general surface-to-surface contact algorithm (STS) is used to simulate the contact. The paper provides an insight into the deformation of the micro products.