According to United Nations statistics1, more than half of the 31 million inhabitants of Central America live in poverty. El Salvador is one Central American country that is struggling with its economy (a per capita income of $2,610 [USD]) and education (an illiteracy rate of 28 percent). In the capital city of San Salvador, however, educators at the Universidad Centro Americana (UCA) are working to improve and modernize the way they teach engineering students as well as promote technological growth in the local engineering community by integrating ALGOR finite element analysis (FEA) software into their curriculum.
Carlos Rivas, Professor of Mechanical Engineering at UCA, led the initiative to implement ALGOR's University Program, which provides affordable, easy-to-use, full-featured FEA software; technical support; and Finite Element Analysis in Practice, a course curriculum kit. "ALGOR is helping us to better prepare students for professional engineering careers in the global marketplace," said Rivas. "Each semester, we expose about 100 students to the software." In turn, as students graduate, the El Salvadoran engineering community gains well-trained engineers who can contribute to modernizing and improving the nation and its economy.
Integrating FEA into the Classroom
Rivas first learned about the finite element method when he was an engineering student at UCA. "A professor talked about the use of finite elements in mechanical engineering design. While later studying for a master's degree at the University of Utah in the United States, I took a finite element course." After Rivas joined UCA's staff, it was his students who prompted him to integrate FEA into the engineering curriculum. "In late 1999, I directed a final project for undergraduate engineering students. They searched the Web looking for a tool to tackle the problem, found ALGOR FEA and proposed the idea of trying the software." Rivas also evaluated ANSYS university software, but it was limited in the size of problem that it could solve. "Because all the capabilities of ALGOR's commercial software are available in our cost-effective university license, we found it more appealing. We have been using ALGOR FEA at UCA ever since."
Rivas explained how instructors and students learn to use the software, "With my background, it was easy for me to learn ALGOR because the software is very user friendly. We viewed some of ALGOR's software-training Web Courses, but our main tool for learning the software was the keystroke-specific tutorials. I encourage my students to use the tutorials and the free Internet software-training material." Because ALGOR is easy to use and provides a wealth of resources to get up and running quickly, students can focus on FEA principles rather than the mechanics of the software. "We show students how to use the software and get results so they know the technology exists and what can be done with it. We also teach the basics of the finite element method so our students can appreciate the power of this tool."
Students then use the software in courses that combine theoretical FEA instruction with practical examples. "We started using ALGOR FEA with mechanical engineering students' final projects. More recently, we formally integrated its use in our Machine Design course, which focuses on the analysis and design of mechanisms. We use the vibration analysis capabilities of the software for the Mechanical Vibrations course, which focuses on the study of vibrations in machines. In the fall 2003 semester, we also began using FEA for our Strength of Materials course, which is taken by our second-year engineering students."
According to Rivas, "The main benefit of using ALGOR FEA as a learning tool has been the ability to perform 'virtual experiments' that demonstrate engineering concepts such as stress, strain and deformation. Instead of performing every experiment in the lab, we have students simulate experiments on the computer, which gives students a better understanding of engineering concepts by providing more of a hands-on feeling. Plus, it saves us money in terms of lab equipment, materials and resources."
The following examples illustrate how UCA engineering students have used ALGOR FEA as a learning tool.
Material Tensile Strength Test
ALGOR FEA is often used for lab exercises in the Strength of Materials course. "We teach the basic concepts in the classroom and then our students compare simulation results," said Rivas. "One of the goals of the course is that our students get a 'physical sense' of the concepts of stress and deformation. Sometimes that sense is difficult to achieve in a lab because the deformation tends to be too small to be visualized. With ALGOR's visualization tool, the Superview IV Results environment, however, the ability to scale deformation enables students to clearly see the behavior of a material under stress and gain a better understanding about how a body reacts to a force."
For one Strength of Materials lab exercise, students analyzed a 1/2"-thick, rectangular bar made of steel ASTM A-36 and subjected to a tensile force of 8,000 lbs. "We solved this problem in the classroom, calculating the stress as well as the deformation of the bar," said Rivas. "Then, students simulated the bar using 2-D elements and compared the results."
Students used the Superview IV Results environment to scale the deformation for easier visualization. "With a deformation scale of 20 percent, it can be clearly seen that the bar stretches in the direction of the applied force and it shrinks in the direction perpendicular to the applied force," said Rivas. "The visualization of this deformation helps our students better understand how the material behaves under the applied force."
Failed Utility Pole Clamp
Students in the Machine Design course investigated the cause of failure for a steel clamp that holds electrical cables on street utility poles. "Two of the clamps are bolted together around the pole," explained Rivas, "and several of the clamps broke during installation. Our engineering staff investigated this problem and determined that the failure was caused by a deficiency in the manufacturing process. Later, we used ALGOR to verify the physical test results."
Students used a digitizing table to obtain precise coordinates for the clamp cross section. The points were then used to draw the cross section in ALGOR's Superdraw environment. Using automatic mesh generation capabilities, a 2-D finite element mesh was created and then copied to produce a 3-D model. Loads and constraints were applied and then the model was analyzed to obtain the stress distribution in the clamp. "The simulation showed that the zone in which the fracture occurred was subjected to the highest stresses," said Rivas.
He added, "The simulation helped our students better understand how the clamp behaved under stress, which, combined with our physical test results, gave them criteria for explaining how the clamp failed and how to correct the manufacturing process."
Kinematic Mechanism Design
For a project in the Machine Design course, students had to design a mechanism that could draw a pattern of circles on a metal sheet. One step in the design process was to simulate the proposed design in ALGOR software. "We teach our students how to design a mechanism to achieve a desired movement," said Rivas. "They solve for the motion of the mechanism by calculating displacement and velocities using basic kinematic theory. Then, they simulate the mechanism and compare the results. By using ALGOR, our students can test several ideas to make the mechanism work as requested without actually building physical prototypes."
Students employed several features of the software that helped them to complete the project. "ALGOR's KinePak mechanism wizard was very helpful," said Rivas, "because students could use it to easily simulate several types of kinematic mechanisms, such as a four-bar linkage. Students built their finite element models using beams, trusses, actuators, sliders, prescribed displacements and rotations to achieve the desired movement. Mechanical Event Simulation (MES) was then used to simulate the motion of the mechanism, which helped students understand the large-scale motion of the model including inertial effects. The Superview IV Results environment's graphing capabilities enabled students to verify that the mechanism movement was accurate because it tracked the position of the parts, allowing students to be sure that the circles were drawn where they should be."
Rivas explained, "Students now choose from one of 13 different proposed designs, build a 3-D model of it and then analyze it using kinematic elements. ALGOR has allowed us to do virtual prototyping of students' design proposals, giving them better criteria to make design decisions."
Solar Panel Support Structure
Students participated in the entire design process of a steel support structure for an electrical system that was successfully installed in a local community, Izotalio. "This community consists of a small group of buildings where about 18 families live in extreme poverty in a very remote area of El Salvador," explained Rivas. "It can be reached only by four-wheel-drive vehicles in the dry season. In the rainy season, it is impossible to go there by vehicle and it is too far away to walk. Because of the location, the community was not connected to the national electrical grid."
Funds were raised to provide Izotalio with a photovoltaic system, which would generate electricity by using solar panels, store the electricity in an array of batteries, transform the electricity stored in the batteries into alternating current (AC) and then distribute the energy to the buildings. The UCA engineering staff was tasked with designing, building and installing the system. "A steel structure was needed to support the solar panels," said Rivas. "We wanted our engineering students to be involved in the design process, so we had them use ALGOR FEA to simulate the deformation and stresses in the support structure due to the expected loads."
The support structure had to allow the solar panels to tilt in the north-south direction so they would face the sun throughout the year and yield the most electricity. Therefore, the support structure was designed as a mechanism with mobile parts. "The community is located on the top of a mountain," said Rivas, "so the solar panels would be exposed to strong winds, perhaps 50 to 70 kilometers per hour. The structure had to resist the forces exerted by those winds yet be as lightweight as possible to facilitate its transportation." Rivas described another concern, "Due to the remote location of the community and lack of additional funding, there was no possibility of repairing or modifying the structure once installed. If the structure failed and the panels were damaged, there was no possibility of replacing the panels."
Students built a 3-D CAD model of the structure using AutoCAD. "This model helped us to define and visualize how the structure was going to be built," said Rivas. From the 3-D CAD model, a wireframe model was built in ALGOR using beam elements and was analyzed for two load cases: one considering only the weight of the solar panels and the other considering the weight combined with the wind load. "With the simulation, it was possible to determine how the structure would deform as well as which members of the structure were subjected to the highest stresses."
Three photovoltaic generators were installed and electricity was distributed to the school, church and houses of the community. "This system was designed and built in 2001," said Rivas. "To date, it is working perfectly."
In the future, Rivas plans to further integrate ALGOR FEA into the UCA engineering curriculum. "I am very happy that we have the software and we are planning to increase its use. ALGOR is a useful tool for recreating lab experiments and helping our students understand physical phenomena, particularly in strength of materials and machine design. In the near future, we want to extend its use to heat transfer, fluid mechanics and civil engineering courses, especially those related to structural design. Additionally, we are developing a finite element course to be added to our engineering curriculum and we plan to use ALGOR in that course."
There are even plans to introduce UCA architecture students to basic strength of materials concepts. "They will draw shapes in AutoCAD and then analyze them for structural stability in ALGOR," said Rivas. "Additionally, architecture students will use the software to study the effect of wind loads on buildings and structures."
Rivas concluded, "My goal is to spread the use of FEA among our engineering community, not only training students but also working engineers. In El Salvador, there are currently few jobs that primarily use FEA software. Civil engineers use finite element software to design buildings. But, our mechanical engineering community is not well developed, and our mechanical engineers mostly work in management or sales. At UCA, we are working to change this by training students in mechanical design and ALGOR FEA is a key tool to achieve this goal."
Carlos Rivas is a Professor of Mechanical Engineering at the Universidad Centro Americana (UCA) in San Salvador, El Salvador. He earned a bachelor degree in Mechanical Engineering at UCA and a Master of Engineering degree in Materials Science at the University of Utah in the United States.
1 Statistics are per "Central America immersed in poverty," source: dpa Deutsche Presse-Agentur, on the ReliefWeb web site, a project of the United Nations Office for the Coordination of Humanitarian Affairs (OCHA) - www.reliefweb.int.