International Journal of Engineering Studies. ISSN 0975- 6469 Volume 3, Number 2 (2011), pp. 87-94 © Research India Publications http://www.ripublication.com/ijes.htm
Application of LabVIEW on Material Testing D. Chandramohan1 and K. Marimuthu2 1
Ph.D., Research Scholar, Department of Mechanical Engineering, Anna University of Technology Coimbatore, Coimbatore, India E-mail:
[email protected], 2 Associate Professor, Department of Mechanical Engineering, Coimbatore Institute of Technology, Coimbatore, India E-mail:
[email protected]
Abstract This paper describes the implementation of LabVIEW, in a bending of beam (flexural test) experiment in the strength of material laboratory to allow the acquisition of real time data for display, analysis, control and storage. The aim is to be able to control and apply moment to a specimen, and collect data from the resulting deformation in the material. In the torsion test, the mechanical properties of the materials to a twisting moment are obtained by two transducers mounted on the bottom of the grips of the torsion machine. The torque and angle of twist are then acquired using LabVIEW software to obtain the yield shear stress, modulus of rigidity and the ultimate strength. The input moment and the angle of twist are measured directly from torsion transducers. In the flexural test the load and deflection is then acquired using LabVIEW software to obtain the young’s modulus and flexural rigidity. The data acquisition system is provided using the following products from National Instruments: application programming interface; and LabVIEW, software development package. The excel spreadsheet is used to analyze the results. This work demonstrates that instrumentation experience is greatly enhanced by integration LabVIEW into the laboratory. The incorporation of computer data acquisitions into the undergraduate laboratory provides students with a valuable tool for data collection and analysis. Keywords: LabVIEW; material properties; flexural test; torsion test.
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Introduction The use of a computer to imitate an instrument or device is known as virtual instrumentation. One software development package used to create virtual instruments is LabVIEW (laboratory virtual instrument engineering workbench). LabVIEW is a graphical programming language that, when used in conjunction with a data acquisition device and personal computer, allows the user to control devices, collect, manipulate and display data. Written code is not used in LabVIEW, instead graphical representations of the circuits are constructed which is called virtual instruments (VI’s). These VI’s are manipulated to perform the desired tasks at hand. The VI’s (virtual instruments) in LabVIEW are run from their front panels. This is the panel with all of the controls and displays. Each front panel has an associated block diagram. This block diagram is built using the graphical programming language G. The components of the block diagram represent different structures, loops and functions. The wiring of the block diagram Represents flow of data between these components. A VI becomes a sub VI when it is placed inside the block diagram of another VI. These sub VI’s are analogous to sub routines, and allow layering and modularity of the VI’s.
Dataflow programming The programming language used in LabVIEW, also referred to as G, is a dataflow programming language. Execution is determined by the structure of a graphical block diagram. Graphical programming LabVIEW ties the creation of user interfaces (called front panels) into the development cycle. LabVIEW programs/subroutines are called virtual instruments (VI’s). Each VI has three components: a block diagram, a front panel, and a connector panel. The last is used to represent the VI in the block diagrams of other, calling VI’s .Controls and indicators on the front panel allow an operator to input data into or extract data from a running virtual instrument. A benefit of the LabVIEW environment is the platform independent nature of the g code, which is (with the exception of a few platform-specific functions) portable between the different LabVIEW systems for different operating systems. There is a low cost LabVIEW student edition aimed at educational institutions for learning purposes. There is also an active community of LabVIEW users who communicate through several e-mail groups and internet forums. The human computer interface structure In this course we have divided the human computer interface (HCI) into three parts: the input/data acquisition, the computer recognition and processing, and the output/display these set of notes describe in detail the first component, the input/data acquisition, i.e., the way in which information about the user is conveyed to the computer.
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Figure 2.2.1: Human computer interface structure.
Figure shows how information from the human is passed to the computer. It separates the process into three parts: sensors, signal conditioning, and data acquisition. The choice made in the design of these systems ultimately determines how intuitive, appropriate, and reliable the interaction is between human and computer.
Figure 2.2.2: interaction between human and computer.
Signal conditioning After the information about the user is measured by a sensor, it must be changed to a form appropriate for input into the data acquisition system. Signal conditioners modify the sensors dynamic range to maximize the accuracy of the data acquisition system, removing unwanted signals, and limiting the sensor's spectrum. Additionally, analog signal processing may be desired to alleviate processing load from the data acquisition system and the computer. Data acquisition system A data acquisition system is a device designed to measure and log some parameters. The purpose of the data acquisition system is generally the analysis of the logged data and the improvement of the object of measurements. The data acquisition system is normally electronics based, and it is made of hardware and software. The hardware part is made of sensors, cables and electronics components. The software part is made of the data acquisition logic and the analysis software. Data logging, carried out by a data acquisition system (DAS), can be used to measure the required parameters and the measurement data is then stored for analysis to improve quality assurance.
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Equipment setup The equipment was set up as shown in Figure 3.1 the VI’s were written and run with LabVIEW 6.0 Student Edition.
Figure 3.1: Experimental setup for deflection testing machine.
This VI will collect the load data, calculate Young’s modulus, flexural rigidity and write all of this data to a file, which can be later opened with a spreadsheet program. The user must first enter a file name, to which the data will be saved, the time interval for the collection of data, and the length, thickness, and breath of the specimen. The VI begins by zeroing the first channel and then collecting data from both channels of the Display at the specified interval. This data will displayed in both numerical and graph form. The graph allows the user to observe the relationship between the applied force and the deflection. Depressing the Suspend button allows the user to interrupt the collection of data. With the Suspend on, the VI will write zeros to the file at the specified time interval. Depressing the Suspend button once more resumes the collection and writing of the data. The Stop button on the VI ends the collection of data and terminates the running of the VI.
Figure 3.2: User interface for virtual laboratory setup for deflection test (front panel).
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Figure 3.2: LabVIEW programming for deflection test (back panel).
Figure 3.4: Experimental setup for torsion testing machine.
In torsion test, VI will collect the torque and twist angle data, calculate shear stress and shear strain and write all of this data to a file, which can be later opened with a spreadsheet program. The user must first enter a file name, to which the data will be saved, the time interval for the collection of data, and the diameter and length of the specimen. The VI begins by zeroing the first channel and then collecting data from both channels of the Display at the specified interval. This data will display in both numerical and graph form. The graph allows the user to observe the relationship between the applied torque and the angle of twist. The diameter and length of the specimen are utilized in the calculations of shear stress and shear strain.
Figure 3.5: User interface for virtual laboratory setup for torsion test (front panel).
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Figure 3.6: LabVIEW programming for torsion test (back panel).
Possible future action In recent years, for high performance natural fiber composites are widely accepted as the best candidates due to their very good mechanical properties. This Research concentrates on the biomaterials progress in the field of orthopaedics. An effort to utilize the advantages offered by renewable resources for the development of biocomposite materials based on biopolymers and natural fibers. This research work focuses on fabrication of natural fiber powdered material (Sisal (Agave sisalana), Banana (Musa sepientum) & Roselle (Hibiscus sabdariffa)) reinforced composite plate material with bio epoxy resin Grade 3554A and Hardener 3554B as a replacement for orthopaedics alloys such as Titanium, Cobalt chrome, Stainless steel and Zirconium and this plate material can be used for internal fixation on fractured bone. In this work, the variation of mechanical properties such as tensile, flexural, and impact strengths of Sisal and banana (hybrid) at a ratio of 1:1, Roselle and banana (hybrid) at a ratio of 1:1 and Roselle and sisal (hybrid) at a ratio of 1:1 composites at dry and wet conditions will be studied using LabVIEW to predict the deflection, Young’s modulus, flexural rigidity (from flexural test), tensile stress, tensile strain, Young’s modulus(from tensile test) and impact strength (from Izod &Charpy test) of NFRPC material.
Figure 4.1: The methodology of the work to determine material properties of NFRPC material using LabVIEW.
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Conclusion In this experiment, Programme has been created using LabVIEW used to investigate the mechanical properties of materials subjected to bending load and twisting load. The use of virtual instruments created with LabVIEW allows the user to quickly investigate and gather data, and also serves to introduce many students to the use of virtual instruments. /faculties/researchers to the use of virtual instruments. The time student takes to complete the experiment are significantly reduced by using computer data acquisitions. This work demonstrates that the capability to rapidly acquire, display and analyze data provides a valuable tool to students.
Acknowledgement We express our sincere thanks to my beloved parents for their invaluable love; moral support and constant encouragement in my life.We owe immense gratitude to our principal Prof.Dr.V.Selladurai,Ph.D., Coimbatore Institute of Technology, Coimbatore for his moral support during the course of my Research work. We sincere thanks to Prof.Dr.G.Sundararaj,Ph.D., Professor, Department of Production Engineering, P.S.G.College of Technology, Coimbatore and Prof.Dr.I.Rajendran,Ph.D., Professor and Head, Department of Mechanical Engineering, Dr.Mahalingam College of Engineering &Technology, Coimbatore for their valuable guidance and suggestions. This research was sponsored by the INSTITUTION OF ENGINEERS (INDIA), KOLKATA. We wish to acknowledge their support. We would like to acknowledge THE CONTROLLER OF PATENTS & DESIGNS, The Patent office, Chennai, INDIA for filed this research work provisional specification [PATENT APPLICATION NO.2349/CHE//2010]. We would also like to acknowledge Dr.L.Karunamoorthy, Ph.D., Professor and Head of Central Workshop at the ANNA UNIVERSITY, CHENNAI for his help in SEM and EDX Analysis. We would like to thank the Reviewers of this editorial system for their valuable inputs and comments.
References [1] Craig, R.R., and McConnell, L., "Virtual Instruments Revitalize an Undergraduate Measurements and Instrumentation Course, 1999 annual ASEE Conference Proceedings, Charlotte, NC, June 20 - 23, 1999 [2] Madsen, H.O., Krenk, S. and Lind, N.C., “Method of Structural Safety,” Prentice-Hall Inc., 1985. [3] Paris, P.C., “The Fracture Mechanics Approach to Fatigue,” Fatigue – An Interdisciplinary Approach, Syracuse University Press, Syracuse, New York, pp. 107-132, 1964.a [4] Smith, C.C., Heaton, H.S., and Queiroz, M., "Integration of Computer-Based Data Acquisition Systems into Undergraduate Instrumentation Laboratories, 1992 ASEE Annual Conference Proceedings, Toledo, Ohio, 1992.
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[5] Zhao, Z., Haldar, A., Breen, Jr., F.L., “Fatigue-reliability evaluation of steel Bridges,” Journal of Structural Engineering ACSE, Vol. 120, No. 5, pp. 160823, 1994.
Authors Biography
D. Chandramohan is a Ph.D., Research scholar in Department of Mechanical Engineering, Anna University of Technology Coimbatore, Coimbatore, India. Doing his research under the guidance of Prof.Dr.K.MARIMUTHU, Associate Professor, Department of Mechanical Engineering Coimbatore Institute of Technology, and Coimbatore, INDIA. He received his M.E., Degree at Alagappa Chettiar College of Engineering and Technology, Karaikudi from Anna University, Chennai. He is an Assistant Professor in Department of Mechanical Engineering, Adhiyamaan College of Engineering (Autonomous), Hosur. His research interests include LabVIEW, Materials Science in the field of Orthopaedics.
K. Marimuthu received his M.E., and Ph.D., Degree at PSG College of Technology and Coimbatore Institute of Technology from Bharathiyar University in 1999 and 2007. He is an Associate Professor, Department of Mechanical Engg., Assisting HOD to prepare PROJECT PROPOSALS to AICTE//DST, Researcher in Advanced manufacturing Technology, NSS Programme officer and Residential Deputy Warden (CIT Hostel) at Coimbatore Institute of Technology, Coimbator, INDIA. His research interest included in the area of welding, Surface Engineering, Computer Aided PTAW Process Modeling, LabVIEW, Material Science, optimization, Reverse Engineering and Rapid Prototyping.
