Infrastructure asset management: a key building block for sustaining rural water services

With high levels of non-functionality and low levels of service, it is clear that rural water assets are not being adequately managed. It is also a symptom of the current focus on first time access, which needs to shift to a focus on long term service delivery. There is a need for actors within the rural water sector to follow other infrastructure-heavy and professionalised industries, and start adopting asset management practices. This paper gives an overview of the main components of infrastructure asset management and makes a case for wider adoption in the rural water sector (for all types of rural water systems, including both hand pumps and piped schemes) in developing countries. It provides new evidence from a case study on good practices from rural municipalities in South Africa and identifies first steps for under-resourced municipalities

Three-dimensional Numerical Analysis of a Joint Bonded Reinforced with Silica Nanoparticles (SiO2)

Nanostructured adhesives may be defined as those materials whose elements imbedded in an epoxy matrix have dimensions in the 1 to 100 nm range. One of the most interesting aspects of ceramic nanoparticles is that their mechanical properties depend strongly upon the particle size and shape. Silica nanoparticles (SiO2) have different physical and mechanical properties from bulk ceramics. The aim of the present study is to investigate the effect of the nanoparticles rate on the equivalent stress, peeling stress and shear stress as well as the strains developed in the adhesive joint. Three-dimensional finite element models of adhesive joint were developed to determine the stress intensity as well as strain with different nanoparticles rate in the epoxy resin. Dispersion of nanoparticles with different percent in the epoxy resin allows for reinforcing the adhesive. Polymer embedded silica nanoparticles (SiO2) proved to be highly effective

Strain Energy Density Prediction of Mixed-Mode Crack Propagation in Functionally Graded Materials

The objective of this work is to present a numerical modeling of crack propagation path in functionally graded materials (FGMs) under mixed-mode loadings. The minimum strain energy density criterion (MSED) and the displacement extrapolation technique (DET) are investigated in the context of fracture and crack growth in FGMs. Using the Ansys Parametric Design Language (APDL), the direction angle is  evaluated as a function of stress intensity factors (SIFs) at each increment of propagation and the variation continues of the material properties are incorporated by specifying the material parameters at the centroid of each finite element (FE). In this paper, several applications are investigated to check for the robustness of the numerical techniques. The defaults effect (inclusions and cavities) on the crack propagation path in FGMs are examined

Two-dimensional fracture analysis of FGM under mechanical loading

This paper extends the concept to isotropic functionally graded materials and addresses fracture problems under mechanical loading. The mode-I and mixed mode stress intensity factors (SIFs) are determinate by combination between the finite element method and the displacement extrapolation technique (DET). The variation continue of the elastics properties is incorporated at the centroid of each finite element, using the Ansys Parametric Design Language (APDL). In this work, two examples are analysed to check for the robustness of the present approach, the FGM disk with a central inclined crack subjected to concentrated couple forces and the three-point bending specimen with crack parallel to material gradation. The numerical results obtained by present technique are discussed by comparison with other published results

Numerical analysis of bonded composite patch efficiency in the case of lateral U and V-notched aluminium panels

In this study, the finite element method is applied to investigate the mechanical behavior of aluminium notched structures reinforced by composite patch. In order to evaluate the efficiency of patches in the case of lateral semicircular and V-notches, it is very important to analyze the stress distribution at the notch tip and to take in consideration the influence of the geometrical and mechanical properties of the patch and the adhesive. Simple and double patch were used as reinforcement techniques. Results showed that the stress concentration factor is reduced at the notch tip by using a double patch reinforcement. This reduction becomes more noticeable when the patch thickness increases

Experimental and FE Modeling of Mixed-Mode Crack Initiation Angle in High Density Polyethylene

In this paper, an experimental and a numerical analysis were carried out using High density polyethylene (HDPE). Sheets with an initial central crack (CCT specimens) inclined with a given angle are investigated and compared to the loading direction. The kinking angle is experimentally predicted and numerically evaluated under mixed mode (I+II), as a function of the strain energy density (SED) around the crack-tip, using the Ansys Parametric Design Language (APDL).According to the experimental observations and numerical analysis, the plan of crack propagation is perpendicular to the loading direction. Moreover, as suggested by Sih in the framework of linear elastic fracture mechanics (LEFM), the minimum values Sminof the factor S are reached at the points corresponding to the crack propagation direction. These results suggest that the concept of the strain energy- density factor can be used as an indicator of the crack propagation direction

A STRAIN ENERGY DENSITY THEORY FOR MIXED MODE CRACK PROPAGATION IN RUBBER-LIKE MATERIALS

In this paper, a numerical modeling of crack propagation for rubber-like materials is presen-ted. This technique aims at simulating the crack growth under mixed-mode loading based on the strain energy density approach. At each crack increment length, the kinking angle is evaluated as a function of the minimum strain energy density (MSED) around the crack tip, using the Ansys Parametric Design Language (APDL). In this work, numerical xamples are illustrated to demonstrate the effectiveness, robustness and accuracy of the computational algorithm to predict the crack propagation path. The results obtained show that the plan of crack propagation is erpendicular to the direction of the maximum principal stretch. Mo-reover, in the framework of linear elastic fracture mechanics (LEFM), the minimum values of the density are reached at the points corresponding to the crack propagation direction

Use of tools to assess sustainability in the WASH sector

Premature failure of water, sanitation, and hygiene (WASH) infrastructure and decreasing quality of service has resulted in emphasis of principals of sustainability amongst development partners and the investment into the development of tools to help understand and improve WASH services. Currently there are twenty-five tools with clear content and methodology for understanding, measuring, or predicting sustainability. These sustainability tools have been applied 92 times in 52 countries most commonly addressing the technical, institutional, and management areas that affect sustainability. An online survey of the demand for sustainability tools and the results of a desk review of the supply of sustainability tools highlight a gap that exists. Currently there is a need and demand for tools that can be utilized across all project life-cycles and beyond. There is a need for tools which address issues that are specific to sanitation and hygiene and peri-urban or urban areas

When access to improved water points does not lead to use: understanding consumption patterns in Burkina Faso

The correlation between access to drinking water, health care, proper nutrition and other development indicators is well known. At the national level, this often translates into the requirement to allocate additional funding to new infrastructure and in rural areas, this investment focuses mainly on water points and occasionally on small scale piped schemes. The assumption is that investment in infrastructure will lead to widespread use by households, attracted by convenience and quality of service. A recent survey from IRC in Burkina Faso, demonstrates that this is not always the case and a large proportion of households either compliment their domestic water consumption at informal water points, or rely on them for all their needs. This paper presents the results of the survey focused on understanding consumption patterns and identifying lead factors guiding households’ choices