Design for Limit Variability in Quality of Industrial Products: A Case Study of Cutix Cable Manufacturing Company, Nnewi, Nigeria

This paper presents numerical approaches to assessment of process capability and product quality standards for production processes. Onehundred cables produced by cable production process of CUTIX factorywere sampled in order to access their insulation quality. Twenty-five samples were used from bathes in stock and each of the samples has sample size of four. The statistical method was used to establish the mean of distribution, the average standard deviation of samples and the average range of samples to establish the process control limits. The distribution of means of samples was normalized in order to ascertain the conformity of the distribution to normal distribution. The distribution was confirmed normal and transformed to standard normal distribution so that the area under the normal curve applies in the analysis of the process distribution. The area under the normal curve of the distribution was evaluated as 0.94 falling within acceptable limit for processes in control. Process control was established using classical relations and analogies to establish process capability and Process capability index. Control charts were developed for the mean and range of samples for the process monitoring period prior to the evaluation of the process population mean as 5.2, the average standard deviation of the process as 0.60, action limits 6.1 and 4.3 for the mean and for the range 2.3 and 0.0. The coefficient of variation was found to be 11% (0.11), indicating low variability of process. The CUTIX process for cable production thereforeproduces within specification. Above all, the probability of any sampleobservation being in the warning limit is 0.76 while the probability of anysample observation being within the control limit is 0.94, showing that theprocess in control.Keywords: limit variability, quality of products, control limits, processcapabilit

Design for limit stresses of orange fruits (Citrus sinensis) under axial and radial compression as related to transportation and storage design

This article employed the Hertz contact stress theory and the finite element method to evaluate the maximum contact pressure and the limit stresses of orange fruit under transportation and storage. The elastic properties of orange fruits subjected to axial and axial contact were measured such that elastic limit force, elastic modulus, Poisson’s ratio and bioyield stress were obtained as 18 N, 0.691 MPa, 0.367, 0.009 MPa for axial compression and for radial loading were 15.69 N, 0.645 MPa, 0.123, 0.010 MPa. The Hertz maximum contact pressure was estimated for axial and radial contacts as 0.036 MPa. The estimated limiting yield stress estimated as von Mises stresses for the induced surface stresses of the orange topologies varied from 0.005 MPa–0.03 MPa. Based on the distortion energy theory (DET) the yield strength of orange fruit is recommended as 0.03 MPa while based on the maximum shear stress theory (MSST) is 0.01 MPa for the design of orange transportation and storage system

Limit Stress Spline Models for GRP Composites

This paper focuses on the use of Spline functions in modelling the critical stress - strain responses of polyester matrix GRP Composites. Spline functions were established on the assumption of three intervals and fitting of quadratic and cubic splines to critical stress-strain responses data. Quadratic and Cubic spline models for three intervals of data points 0.024 £ x£ 0.036, 0.036 £ x £ 0.061and 0.061 £ x £ O. 12 were established. The optimization of quadratic and cubic models by gradient search optimization gave the critical strain as 0.024, which resulted to strength of approximately 26 MPa. Strain hardening was observed to occurr within a strain range of 0.03 to 0.12 leading to strength of about 62 MPa predicted by Cubic spline. Splines were found to accurately predict the functional values at subinterval, 0.024 £ x £ 0.036 of data points. Spline model is therefore recommended as it evaluates the function at subintervals, eliminating the error associated with wide range interpolation

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Multivariate Time Series Analysis for Optimum Production Forecast: A Case Study of 7up Soft Drink Company in Nigeria

This study focuses on the establishment of an optimum forecast model that predicts future production trends of 7UP Bottling company. Sixty (60)months time series data of 7UP bottling company were used after ascertaining the presence of seasonal variation and trend components of the data to establish the multidimensional forecast model. Predictive Production rate model was developed using a general multivariate regression equation form. The monitoring schemes show values of MSE and MAD as 0.0177 and 0.0658 respectively giving a tracking signal of 0.0. These values established the multivariate forecast model as optimum approach in tracking demand and production trends in a production setup. The value of the standard deviation of distribution of errors of 0.0823 estimated with MAD also confirms the authenticity of this model. The responses shown in the graphics of this study clearly explains the mixed time series which definitely contains seasonal variation and trend components as established in this study. Also the coefficient of determination of 0.957956 explains about 97% fitness of the established model to production data. The trend component associated with time variable (Mtncod) causes production to increase by 0.002579KG/Month. Finally, this work adds to the growing body of literature on data-driven production and inventory management by utilizing historical data in the development of useful forecasting mathematical model.Keywords: production model, inventory management, multivariate timeseries, production forecas

Finite element approach to solution of multidimensional quasi-harmonic field functions

This paper focuses on the methodical approach for the solution of fieldproblems whose function can be expressed as derivatives and integrated functional or on solution of quasi-harmonic functions whose physical behaviors are governed by a general quasi-harmonic differential equation that can be treated as a quadratic functional that can be minimized over a region. The functional of a stress field function was established using mixed methods analogous to variational principle, minimum total potential principle and finite element method. The functional of function, Φ(x,y) was formed using Euler equivalent integral and finite element shape function for a function expressed in derivative form. The minimization of the functional gave the stationary values of the function which minimize the functional. The solution of the functional gave the minimum value of the function. Possible solutions of states that minimize the functional was achieved by finite element solution procedure while the minimum values of the stationary states were solved by solving the functional. The functional obtained for each finite element is minimized with respect to associated degrees of freedom of the element and assembly method applied to all elements minimization equation to obtain system of equations equal to unconstrained nodes in the region .The element equations are assembled and solved by substitution to obtain the values of the function at discrete points. The values of the function at the discrete points did not vary significantly with boundary points values. The minimum value of the function representing the critical or the functional of the function is evaluated as 24MPa

Optimization of Tensile Strengths Response of Plantain Fibres Reinforced Polyester Composites (PFRP) Applying Taguchi Robust Design

This study focuses on the use of control factors(volume fraction of fibers (A), aspect ratio of fibers (B) and fibers orientation (C)) to determine the optimum tensile strength of plantain fibers reinforced polyester resin. Tensile tests was conducted on the replicated samples of plantain empty fruit bunch fiber reinforced polyester composite(PEFB) and plantain pseudo stem fiber reinforced polyester (PPS) respectively using Archimedes principles in each case to determine the volume fraction of fibers. To obtain the optimum properties a Monsanto tensometer were used conduct tensile tests to establish the control factor levels quality characteristics needed to optimize the mechanical properties being investigated. Taguchi robust design technique was applied for the greater the better to obtain the highest signal to noise ratio (SN ratio) for the quality characteristics being investigated employing Minitab 15 software. The optimum values of the control factors are established for empty fruit bunch composites and for pseudo stem fiber composite. The empty fruit bunch fiber reinforced polyester matrix composite has the optimum tensile strength of 40.28MPa , while the pseudo stem plantain fiber reinforced matrix composite has the tensile strength of 30.51MPa. The properties studied depend greatly on the reinforcement combinations of control factors and the composites of empty fruit bunch are stronger in tension than that of pseudo stem. Key Words: composite matrix, plantain fibers, tensile strength, pseudo-stem, empty fruit bunch. Taguchi

Analysis and Application of Natural Fiber Reinforced Polyester Composites to Automobile Fender

In Nigeria, little attention has been given to the analyses and applications of natural fibers for automobile body parts production. Hence in this work, an attempt is made to evaluate the compressive and impact strength of plantain fiber reinforced polyester composites (PFRC) and to develop an automobile fender using plantain fiber reinforced polyester composites. The PFRC automobile fender was constructed using the hand lay-up technique. The method adopted to achieve the PFRC fender involved fiber extraction, fiber surface treatment, laminates development for impact and compressive test experiment and the development of automobile fender. Experimental investigations for compressive and impact tests were carried out on the laminates which were prepared according to the ASTM D256 and ASTM D1621 standards, respectively. The impact strength result of the PFRC with volume fraction 0.25 and 0.3 was 12.22J/m2 and 12.83J/m2, respectively. The compressive strength, shear stress and resultant stress results of PFRC laminates with volume fraction 0.25 and 0.3 were 62.52MPa, 31.26MPa, 69.99MPa and 68.98MPa, 34.49MPa, 77.12MPa, respectively. From the results, it was observed that the strength of the plantain fiber reinforced polyester composites depend on the fiber volume fraction. The constructed automobile fender was simulated in a Solidworks software environment and was found that the edges, especially the circular part of the automobile fender have high stress concentrations. The production of the automobile fender using PFRC was done at low cost

Evaluation of Optimum Asphalt Yield of a Process

This study is on evaluation of optimum asphalt yield of a process. The data used is a secondary data collected from the records department of Consolidated Contractors Company Nigeria Ltd (C.C.C) between years 2008-2010. A fitted trend equation was obtained which enables prediction of the production yield at any point in time. The  trend line estimated from a 12 point centered moving average showed a sharp fall in the production yield of asphalt and a slight rise in the month of August for the three years period. The seasonal analysis showed from the result of the seasonal indices that the month of July has the least production of asphalt and this can be attributed to the presence of heavy rain fall which primarily affects the production of asphalt. Also, regression analysis was used to develop two models that expresses the nature of relationship between the production yield and factors such as Temperature, Humidity, Rainfall, Efficiency(environmental factors), Stone-dust/sand mixture, chippings of various sizes C5, C10, and Bitumen(material factors). Finally, it was established from analysis that the best regression model for predicting the production yield of asphalt is the material factor fitted equation. Key words: Trend, Seasonal index, Environmental factors, Time serie

Finite Element Analysis for Stress-Strain Parameter of Projectile Impeded Glass Fibre Reinforced Polyester (Gfrp) Composites

For the treatment of progressive damage, spatial discretization is required so that numerical techniques such as the finite element method or finite difference method would be advantageous. Finite element and finite difference techniques have also been applied to impact problems because they are more versatile at modeling boundary conditions and local phenomena such as stresses and strain under a point load. This paper investigates the stress-strain magnitude on body amour composites of glass fibre reinforced polyester (GFRP), when hit with ogival and conical nosed projectiles through the application of finite element analysis using ANSYS software version 10.1. The finite element result of the plain stress analysis shows that the composite is stronger in the longitudinal direction. This is supported by the fact that the maximum stress of 328.125MPa was recorded in the X direction while the maximum stress of 57.726MPa was recorded in the Y direction. The analysis also indicates that the maximum influence of the stress was experienced around the incident hole and the minimum at the exterior boarders of the samples. Keywords: Finite Element, Plain Stress Analysis, Projectiles, ANSYS Software, Body Amour, Fibre Reinforcement