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As energy efficient environmentally conscious engineers, we here at Glew Engineering do what we can to save energy and resources both around home and around the office. This might mean choosing products that are more environmentally friendly or energy efficient. It might mean using our surroundings to our advantage, like pulling cold air through a home or office at night so the building needs less air conditioning the next day. The most satisfying thing, though, is to employ our knowledge of mechanical engineering, materials science and thermal management to design custom hand-tooled solutions. In the next few blog posts, I'll review some of the current in-house engineering projects that are underway here and maybe give our readers a little inspiration [...]
Wind Load Comparison between CFD and ASCE 7 for Rooftop shapes Welcome back to our blog series on the phenomenon called Wind Load CFD Modeling and how it affects civil and mechanical engineers. Wind Load is the force that blowing wind exerts on any device or structure that extends above ground level. After an initial introduction to the factors that affect wind load on an object, I compared three different sets of wind load calculation methods using three simple objects, hypothetically placed on a 100-foot-tall building. Starting with generic drag equation for the first equation, added two modification coefficients called "gust factor" and "exposure coefficient" for the second equation. I used the model for rooftop objects for the [...]
Wind Load Calculation Wind Load Calculation is an overview of the force that blowing wind exerts on a tall object. A number of factors that influence the actual wind load on a real building, include the surrounding terrain, nearby structures, trees, and typical weather patterns for the area. Comparing wind load calculations are most complicated . Calculations try to account for as many of these external factors as possible, to the point where the wind load section in American Society for Civil Engineer’s ASCE 7 standard, spans five chapters and over 100 pages. Fig 1: Wind load calculation example structures ASCE 7's Applications Comparing one of ASCE 7’s Applications with the two equations [...]
Figure 1: Simplified model of an aluminum-glass window In last week’s blog, Thermal Expansion in a Glass and Aluminum Window: Part 1, we introduced the basic concept of thermal expansion in solid materials. Since CTE mismatch can impose extremely high stress, during mechanical engineering design one must consider the temperature exposure and expansion or contraction of a material. In order to help the read gain insight, we used a simplified aluminum-framed window to demonstrate that a hot summer day would be enough to shatter glass if the window wasn’t equipped with a flexible gasket between the frame and the glass. For this entry, we utilize a finite element analysis (FEA) to elucidate the stress effects caused by both high and [...]
Italian Masters: Volta Jump-Starts Electrical EngineeringFigure 1: Girolamo Cardano (1501-1576) Welcome back to our series on Italian Masters of math and science. Last week I wrote about Galileo’s extensive accomplishments both in the field of astronomy and beyond. This week, I’ll take a look at another renaissance polymath who dabbled in astronomy, along with his work in mathematics, medicine, biology, chemistry, philosophy, and gambling (yes, seriously): Girolamo Cardano. Cardano is a less well-known figure than Galileo or some of the other scientists I’ve written about who have famous equations or units of measurement named after them, like Volta or Torricelli. He is regarded as one of the greatest mathematicians of his age, however, and made a great many contributions to science, [...]
Equipment designers must accommodate thermal expansion (CTE)of dissimilar materials, especially when they are subject to large temperature changes. This problem is often called "CTE mismatch." In this blog, we give the fundamentals of thermal expansion calculations used in thermo-mechanical analysis. These calculations are simple but useful, and easy enough to perform by hand or with a spread sheet. For more complicated shapes, one must use computer modeling. As an example, we perform a finite element analysis (FEA) in a later blog http://glewengineering.com/thermal-expansion-in-a-glass-and-aluminum-window-part-2/, of a glass and aluminum window and frame to show where the stress is excessive. This points to the obvious need for a gasket to perform as a thermal interface material, in order to lessen [...]
Figure 1: Allesandro Volta We’ve been taking a break from hard-hitting mechanical engineering and materials science blogs with some pieces on the Italian masters of science, mathematics and engineering in the 16-19th centuries. I’ve previously explored the lives and contributions of Evangelista Torricelli, Giovanni Venturi and Giovanni Cassini. For this blog, I’m focusing on Alessandro Volta, who helped revolutionize our understanding of electricity and electrochemstry it in the late 18th century. […]
Figure 1: Mars Exploration Rover mobility testing By NASA
Figure 1: Diagram of the scientific equipment on MER-B Opportunity Mars Exploration Rover Launches Press Kit, June 2003, p. 41 [i] I mentioned in a blog last week that Mars Exploration Rover B (FIgure 1), more affectionately called Opportunity, recently celebrated the 12th anniversary (in Earth years) of its landing on Mars. 12 years without maintenance on the hostile surface of another planet is incredible, considering the original operational time was planned for only 3 months. Mars Science Laboratory Curiosity currently gets the most press, with its larger tool library and fancier cameras, but there are still scientists and engineers at JPL piloting Opportunity from one scientific site to the next. In the last blog, I mentioned [...]
Figure 1: Shear stress results for our concrete slab simulation. The red area of high compression is where the corner of the square-shaped supporting column holds up the slab. © Glew Engineering Consulting, 2016 Welcome to the final entry in our finite element analysis (FEA) blog series, in which I'll discuss a little about analyzing and evaluating FEA results. Over the course of this blog series, I've covered tips on setting up the model in CAD and in the FEA program, configuring the analysis, and generating results. The final step in the process is the analysis of the results, both to get the answers to whatever problem inspired the FEA simulation and to ensure that the final results are [...]
12 Years a Martian: Engineering Challenges on the Red Planet GalleryCAD, Electrical Engineering, Engineering Consulting, Expert Witness, Licensed Mechanical Engineer, Materials Science, Mechanical Engineering, Mechanical Engineering Consulting, Thermal Management
Figure 1: Mars Exploration Rover By NASA/JPL/Cornell University, Maas Digital LLC [Public domain], via Wikimedia Commons Depending on which Facebook pages or Twitter feeds you follow, some of you may have caught wind that Opportunity (Mars Exploration Rover B, Figure 1) recently passed its twelfth anniversary of its landing on the red planet. Opportunity’s ongoing trek across Mars represents a fantastic accomplishment in engineering. At the time I’m writing this, the rover has been in continual operation for over 4,300 Earth days (that’s about 4,185 Sols, or Martian days). Considering its original planned mission time of 92 Earth days, Opportunity has exceeded its design lifetime by 4,700%. Imagine having a car that, instead of a [...]
Figure 1: Displacement results for our concrete slab simulation. The slab is supported in the center by a square column, and on the sides by a theoretical wall. © Glew Engineering Consulting, 2016 Time now for the last in our blog series on FEA. I’ve previously discussed how to set up CAD for FEA, how to mesh that CAD model and the different types of analysis that FEA programs can run. The next step in the process is generating results from the FEA simulation, like the displacement illustration in Figure 1. These are fantastic tools for generating useful reports, and are also very useful in helping an FEA consultant or engineer check the accuracy of the own results. As a [...]
Figure 1: Mesh, loads and constraints, ready for analysis © Glew Engineering Consulting, inc. 2016 Welcome again to our series on finite element analysis (FEA). In the last blogs, I covered steps on setting up a computer-aided design (CAD) model and how to set up the mesh and boundary conditions, the most crucial steps in FEA simulation. In this blog, I’ll look at the actual simulation and analysis, which can be the most time-consuming stage in the process. As a reminder, for an example I’ve been using a recent project we worked on involving punching shear in reinforced concrete. We were examining the effectiveness of reinforcing a column-supported concrete slab against the possibility of that column punching through the concrete. Types of [...]
Thermal Mass Flow Controllers A mass flow controller (MFC) for each gas line in a semiconductor tool’s gas panel measures and regulates the mass flow of the gas in order to set the gas entering the process chamber to the values in the process recipe. While pressure regulation and temperature control are needed for sensitive chemical vapor deposition (CVD), plasma etching, or thin film processes, gas flow control can be just as important. Semiconductor process recipes involve precise ratios of gas phase chemical to assure the correct stoichiomtery and reaction rates. Due to the accuracy and precision required of the gas flow rate, mass flow controllers are often the most sensitive and expensive components installed in a gas [...]
An article on pressure transducers used in semiconductor fabs and semiconductor equipment.
Pressure gauges and pressure transducer use in semiconductor fabs.
Devices for regulating gas pressure in semiconductor processes.
Valve specification and design for high purity semiconductor equipment.