Print ISSN: 1681-6900

Online ISSN: 2412-0758

12A,

12A


Developing an Approach to Redesign Freeform Surfaces Using B-Spline Technique

Amjad B. Adulghafour; Ahmed T. Hassan

Engineering and Technology Journal, 2018, Volume 36, Issue 12A, Pages 1213-1221
DOI: 10.30684/etj.36.12A.1

In product design process trends currently tend to use sculpture surface (freeform surface) that modeling by using (NURBS, B-spline, Bezier) technique to suit aesthetic, functional and manufacturability requirements. The B-Spline technique is one of the most important tools in computer aided geometric design (CAGD). This paper reported a new approach to design 3D freeform CAD model and then represented this model mathematically by using B-Spline technique. This mathematical represent consider one of the important aims that useful in manufacturing process through its geometric data which defines by this represent. The approach has three major steps: design 3D CAD solid contain freeform surface by using CAD software, analysis and extraction the parameters including geometric data of 3D CAD model based on IGES file format, and then construction the B-Spline surface of the model that contain multi patches by using basis function of the surface. The approach has been extensively tested with more than case study has 3 degrees of the surface then represented mathematically in four patches.

Comparison Between Deterministic and Stochastic Interpolation Methods for Predicting Ground Water Level in Baghdad

Muammar H. Ali; Aqeel Sh. Al-Adili; Nagaratnam Sivakugan

Engineering and Technology Journal, 2018, Volume 36, Issue 12A, Pages 1222-1225
DOI: 10.30684/etj.36.12A.2

Surface interpolation techniques are usually used to create continuous data (i.e. raster data) from distributed set of point data over a geographical region. There are deterministic and stochastic (geostatistical) interpolation techniques can be used to create spatial raster surface. In this paper, the comparison between the Inverse Distance Weight (IDW) interpolation method as deterministic method and the Kriging interpolation method as stochastic method is done to determine the best performance for measuring levels of ground water in Baghdad Governorate. Spatial raster surface surfaces as ground water prediction maps are generated from each method by using average ground water level measured at 206 wells in the study area. These maps are shown spatial variation in the ground water levels and they have complete different. The IDW method results a refined map and lesser error than the Kriging method. Thus, the analysis shows that the IDW gives better real performance of measuring levels of ground water in Baghdad Governorate.

Mechanical Properties Modeling and Optimization for Polymeric Matrix Hybrid Bio Composite for Scaffolds Application

Jenan S. Kashan; Marwan N. Arbilei

Engineering and Technology Journal, 2018, Volume 36, Issue 12A, Pages 1226-1235
DOI: 10.30684/etj.36.12A.3

TiO2 / Polypropylene composite considers very promising biomaterials in bone replacement and repair application, but mechanical properties still out of load bearing scaffolds application. In this work, two approaches were suggested to produce enhanced polymeric matrix bio composite for scaffolds application, 1st one was by using Nano TiO2 particles to produce bio composite with good mechanical properties. while the 2nd approach applied by the addition of Al2O3 Nano particles. Different processing conditions have been used like different compounding pressures, compounding temperatures, and chemical composition. This work aimed to investigate the effect of these additions and processing factors on mechanical and physical properties for the proposed composite. Linear and multiple regression modeling techniques approached, and the mathematical models have been concluded and evaluated. The optimum preparation factors have been reduced and analyzed with Taguchi method to find the best preparation criteria to prepare the best mechanical properties product. Using Nano scale TiO2 powder enhanced mechanical and physical properties, moreover the addition of Nano Al2O3 powder maximize the mechanical properties to very similar values to natural bone.

Investigation of The Effect of Loading Paths in the Tube Hydroforming Process

Adil. Sh. Jaber

Engineering and Technology Journal, 2018, Volume 36, Issue 12A, Pages 1236-1243
DOI: 10.30684/etj.36.12A.4

The control accurately of internal pressure, axial feeding and paths of loading which have important influences on the final tube quality. In this research an impact of loading path of the tube hydroforming process and final part requirements ( i.e. thickness specification and shape conformation) were studied numerically. Small bulge shape tube hydroforming parts were utilized in the finite element analyses to get several guidelines on the effect of the relation between the internal pressure and axial compressive feeding programs. Two dimension model of bulge shape tube (50 mm) bulge width has been developed from cylindrical tube with thickness (2mm) of the copper and (60 mm) outer diameter. A commercial available finite element program code (ANSYS 11), is used to perform the numerical simulation of the tube hydroforming operation. The results demonstrate that, the loading path has very important influenced on the thickness distribution over the tube and capability attained the target shape of the required product.

Study of the Mechanical Properties of Jute Fiber Reinforced Cement Composites

Lamees S. Faiq

Engineering and Technology Journal, 2018, Volume 36, Issue 12A, Pages 1244-1248
DOI: 10.30684/etj.36.12A.5

The study results show the use of jute fibers to develop a low cost material for wall panels, roofs and other construction board. The study has been investigates the cement mechanical characteristics jute fibers reinforced concrete. Different lengths of fibers (2cm) and (4cm) were mixed to act as reinforcement for the concrete samples. The samples with different fiber percentages (0.5%, 1% and 1.5% by weight of cement) were tested in axial compression and splitting tensile strength. A total of (42) concrete cube samples (100mm*100mm*100mm) and (42) cylindrical samples (100mm*200mm) were used in the tests, these include compressive and splitting tensile strength and were conducted at (7) and (28) days of concrete age. The results showed that increasing the fiber content and length leads to a slight decrease (4.3% - 12.3%) in the compressive strength but it improves the splitting tensile strength which reached best value at the (1% by weight of cement) fiber content and (5cm) length. The increasing of splitting tensile strength was up to (19.4%) from the reference concrete strength.

Robust Multiple Model Adaptive Control for Dynamic Positioning of Quadrotor Helicopter System

Safanah M. Raafat; Zainab SH. Mahmoud

Engineering and Technology Journal, 2018, Volume 36, Issue 12A, Pages 1249-1259
DOI: 10.30684/etj.36.12A.6

The quadrotor control has been one of the benchmark control problems. It is considered as an under-actuated, multivariable and high nonlinear system due to its dynamics, having strong coupling between translation and angular motion and affected by external disturbances associated with flight environment. Therefore, there is a need to design a robust control that can keep up with sudden changes and find better tracking performance against modeling error and uncertainties. In this work, an adaptive state feedback control method denoted as Classical Multiple Model Adaptive Control (CMMAC) has been implemented. This method embodies in its structure a bank of filters. Kalman filter (KF) has been used where each filter has been designed for a specific value of an equilibrium point and set of controllers, which was provided by the LQ-servo design. Comparisons of the performance of a quadrotor system between control designs for single Kalman filter with CMMAC for the same value of uncertainty in terms of Root Mean Square Error (RMSE) have been presented. CMMAC meets better performance of tracking design for all variations; the performance of the controlled quadrotor has been improved for the linear and angular coordinates 100%, as compared to the performance when using one Kalman filter.

Resistance of High-Volume Fly Ash Self-Compacting Concrete to Internal Sulfate Attack

Tareq S. Al-Attar; Ahmed A. Taha

Engineering and Technology Journal, 2018, Volume 36, Issue 12A, Pages 1260-1266
DOI: 10.30684/etj.36.12A.7

This paper investigates the durability of high-volume Fly ash self-compacting concrete, HVFASCC that exposed to internal sulfate attack. At the present work, HVFASCC was produced with two Fly ash replacements: 50 and 60% by weight of Portland cement. The internal sulfate attack was simulated by adding natural gypsum (CaSO4) that contain ion (SO3-2) to fine aggregate by two weight percentages: 1 and 2%. Limestone dust was used as filler with a content of 100 kg/m3. The cementitious materials, cement and Fly ash, content was 400 kg/m3 and the water to powder ratio for the studied mixes was 0.34 by weight. To ensure the self-compact ability of the mixes, slump flow, T500, V-funnel and L-box tests were done. The Compressive, Splitting and Flexural strength Tests were extended to the age of 240 days. The results showed that there is no significant difference between 1 and 2% of SO3 content on the behavior of all mixes. The presence of limestone powder in the paste solution could have a role in stabilizing ettringite and reducing paste porosity at early ages. At later age, 240 days, the harmful effect of SO3 is diminished and that may be caused by the depletion of gypsum and the dominant product will be calcium monosulfoluminate hydrates instead of calcium sulfoaluminate hydrates.

Experimental and Numerical Study of the Earing Defect During Square Deep Drawing Process

Kariem M. Younis; Adil. Sh. Jaber

Engineering and Technology Journal, 2018, Volume 36, Issue 12A, Pages 1267-1275
DOI: 10.30684/etj.36.12A.8

Deep drawing process is a very complex process which controls a lot of parameters and the associated defects. The aims of this research are to discuss the effect of parameters of the process utilized in square deep drawing process such ; material properties, blank size, blank shape on the height and shape of earing defect appear of the drawn cup. Three dimensions model from low carbon steel (AISI 1008) with thickness 0.7mm of square cup (41.4mm by 41.4mm). The finite element software (ANSYS 11) was utilized to carry out the numerical simulation of the deep drawing process, and the experimental work result of earing was compared with numerical of earing shape result. In this work, three types of the radius of die entry of 3, 5, 7mm, three shapes of the blank (circular, octagonal, and square) with various diameters, four types of radius of the punch profile of 3, 5, 6, and 7mm had been selected to form a cup with square sides. The results show that, The circular blank give the best results according to earing defect and useful height of the drawn cup, when square shape of blanks were utilized, excessive earing will show in the square cup, due to non-uniform distribution of blank material around the perimeter of the die cavity, minimum material in the flat side and too much material found in the die corner, while when using octagonal shape of blanks which have a same surface area to the square blank, the earing will reduce in the corner of the cup due to extract of the too much material from the blank corners. The results showed a high agreement between the experimental work and numerical simulation reached to 85 % in terms of the shapes and lengths of the earing appearing in the square cups.

Investigation Vibration Damping in the Hydraulic Systems by Using an Accumulator

Walaa M. Hashim; Huda A. Al-Salihi; Hisham A. Hoshi

Engineering and Technology Journal, 2018, Volume 36, Issue 12A, Pages 1267-1282
DOI: 10.30684/etj.36.12A.9

It is generally accepted that the vibration of fluid power systems considered to be one of the major problems that is normally occurred in the hydraulic system, which causes a noise and short life of its components. Accordingly, it should be reduced the efficiency as well as an increase leakage system. Hence, present study pays more attention to investigate a bladder an accumulator which was successfully added to the hydraulic system in order to reduce the vibrations that might be generated by the system and decelerate the actuator at the end stroke. Which variables are measured before relief and directional valve and at the linear cylinder body. It was found that the maximum percentage damping in vibration velocity at a position before relief and directional control valve and at cylinder body was 20%, 20.8% and 55% at 20 and 15 bar pressure supply respectively. Whereas, it was observed the acceleration was 11.3%, 12.5% and 50% at 40 bar pressure supply. Also, it was found that the piston begins decelerate gradually from distance 25cm in which equal to 1/6 of total stroke length with a period of time 5 seconds.

Some Mechanical Properties of Polymer Matrix Composites Reinforced by Nano Silica Particles and Glass Fibers

Sudad Younis; Jawad K. Oleiwi; Reem A. Mohammed

Engineering and Technology Journal, 2018, Volume 36, Issue 12A, Pages 1283-1289
DOI: 10.30684/etj.36.12A.10

This research studied the effect of nano silica particles on wear behavior test , ultimate tensile strength ,impact strength, fracture toughness and hardness shore D of specimens composite material. The hand-lay-up method is used to preparation of specimens established from unsaturated polyester resin matrix reinforcement with 4% weight fraction glass fiber (chopped / woven) mat and 1%, 3%, 5% weight fraction of nano silica particle. The nano silica particles used in this study has an average size of (less than 45nm). The results showed that the specimen (up+4% woven glass fiber+5% nano SiO2) gives better mechanical properties include ultimate tensile strength, impact strength, fracture toughness and hardness shore D (110 MPa, 13.7 K.J/m2, 18.92 MPa.m1/2, 85 shore D) respectively,when compare other specimens. The wear rate decreased from (22.5×10-4 cm3/N.m) for specimen (pure unsaturated polyester resin) to (0.18×10-4 cm3/N.m) for specimen (UP+4% woven glass fiber +5% nano SiO2) under parameter 7N (load), 15 minutes (sliding time), 2m/s (sliding speed) and (7 cm) sliding distance.

A Simplified Recurrent Neural Network Trained by Gbest-Guided Gravitational Search Algorithm to Control Nonlinear Systems

Omar F. Lutfy; Ahmed L. Jassim

Engineering and Technology Journal, 2018, Volume 36, Issue 12A, Pages 1290-1301
DOI: 10.30684/etj.36.12A.11

This paper presents a feedback control strategy using a Simplified Recurrent Neural Network (SRNN) for nonlinear dynamical systems. As an enhancement for a previously reported modified recurrent network (MRN), the proposed SRNN structure is used as an intelligent Proportional-Integral-Derivative (PID)-like controller. More precisely, the enhancement in the SRNN structure was realized by employing unity weight values between the context and the hidden layers in the original MRN structure. The newly developed Gbest-guided Gravitational Search Algorithm (GGSA) was adopted for optimizing the parameters of the SRNN structure. To show the efficiency of the proposed PID-like SRNN controller, three different nonlinear systems were considered as case studies, including a control valve, and a complex difference eq.. From an extensive set of evaluation tests, which includes a control performance test, a disturbance rejection test, and a generalization test, the proposed PID-like SRNN controller demonstrated its effectiveness with regards to precise control and good robustness and generalization abilities. Furthermore, compared to other Neural Network (NN) structures, including the original MRN and the Multilayer Perceptron (MLP) NN, the SRNN structure attained superior results due to the utilization of a reduced set of parameters. From another study, the GGSA accomplished the best optimization results in terms of control precision and convergence speed compared to the original Gravitational Search Algorithm (GSA).

Formation Control of Mobile Robots Using Sliding Mode Control Based on Conditional Servocompensator

Laith Khames Majeed

Engineering and Technology Journal, 2018, Volume 36, Issue 12A, Pages 1302-1310
DOI: 10.30684/etj.36.12A.12

In this paper, the problem of controlling a group of mobile robots is considered; each one operates with the nonlinear nonholonomic under actuated dynamics. A coordinated control scheme is designed based on leader-follower(s) method to achieve prescribed formation maneuvers. This objective is fulfilled using the approach of sliding mode controller based on conditional servocompensator, which will bring the system error trajectories into a positively invariant set (boundary layer) close to the origin. Then, a special form of servocompensator conditional integrator, which will be active only inside the boundary layer, will regulate the trajectories to the origin in finite time. Compared to the traditional integral which will deteriorate the performance of the feedback system, the conditional version will have a very insignificant effect on the performance. The simulation results show that the designed controller is able to achieve the objective efficiently with very reasonable control actions.