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 [...]
Portrait of Galileo Galilei Justus Sustermans [Public domain], via Wikimedia Commons I’d like to return to our previous series on the Italian Masters, focused not on the usual masters or painting and sculpture but on the masters or science, mathematics, and engineering. So far in the series I’ve written about the accomplishments of Volta, Cassini, Venturi and Torricelli. Today, I’d like to look at one of the greats: Galileo Galilei. Galileo is most famous today for standing up for heliocentrism against the Catholic Church and spending the last years of his life under house arrest as punishment. However, Galileo didn’t let controversies or confinement stop him, and accomplished a great amount of research in not only [...]
Figure 1: Mars Exploration Rover mobility testing By NASA
Fig. 1 Tall Fire from Chemical We have written about pyrophoric materials in a number of Glew Engineering’s previous blogs on safety in semiconductor fabrication, but have yet to cover how to define it or its danger. At its simplest, a pyrophoric substance is any substance that spontaneously ignites in room temperature air. As one might imagine, spontaneous combustion on contact with the regular atmosphere we live in can be quite dangerous. Last year, Glew Engineering assisted a research lab in designing a safe gas distribution system for their plasma-enhanced chemical vapor deposition chamber. During the initial work, the building administrators and safety managers were concerned about the lab’s proposed use of silane and germane, two pyrophoric and toxic materials. To them, [...]
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 [...]
Figure 1: Giovanni Domenico Cassini 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. In previous blogs, I explored the lives and contributions of mathematician/physicist Evangelista Torricelli and physicist/engineer Giovanni Venturi. For this blog, I'm focusing on Giovanni Domenico Cassini (Figure 1), a structural engineer and astronomer extraordinaire in the late 17th century. Cassini started small, studying astrology (not astronomy!) early on in his career, but his fascination with the actual scientific properties of our celestial neighbors and his lifelong dedication to watching the night sky led him to a number of great discoveries. Giovanni Domenico Cassini (1625-1712) Giovanni Domenico Cassini [...]
We'll continue on now with our blog series on finite element analysis (FEA). After discussing how to best set up a computer-aided design (CAD) model for FEA simulation, in this blog I'll cover the next step: meshing the model and applying boundary conditions. "Meshing" is the process by which the CAD model is separated into discrete finite elements; it can be done in the same program that runs the FEA numerical simulation later, or it might be performed in a standalone program, depending on your software. Boundary conditions are the loads (forces, movements, impacts, etc) and constraints that interact to actually cause deformation and stress in each element, and in turn the model as a whole. Mesh Generation The mesh essentially [...]
Figure 1: Giovanni Battista Venturi [i] Glew's News is doing a short series highlighting the lives and accomplishments of the Italian Masters of science, engineering, and mathematics. In the last blog, I wrote about Evangelista Torricelli, a mathematician and physicist from the 17th century. In this blog, I'm focusing on Giovanni Venturi (Figure 1), an accomplished physicist, hydrodynamicist and engineer. Giovanni Battista Venturi (1746-1822) Giovanni Venturi was born to a wealthy family in Reggio, Italy in 1746. A talented young student, by the age of 23 the local seminary had already ordained him as a priest and professor. His talents in mathematics didn’t long escape notice at the nearby University of Modena, which appointed him as a professor of geometry and [...]
Figure 1: Reinforced concrete mesh © Glew Engineering Consulting Welcome back to our blog series on FEA. In the last blog entry, we introduced some of the fundamental concepts in finite element analysis (FEA). This entry in the blog series focuses on the initial steps in preparing a computer-aided design (CAD) model ready for use in an FEA program. Since FEA programs are very sensitive to the data they have to work with, it's important that the CAD models being analyzed are compatible with the analysis methods the FEA program uses. In order to illustrate my points throughout the blog series, I will introduce a recent FEA consulting project that we completed. Modeling Punching Shear in a Concrete Slab We were recently approached by an academic, who was examining [...]
Figure 1: Evangelista Torricelli Most people are familiar with the works of the “Italian Masters”… artists such as Leonardo da Vinci, Michelangelo and Raphael. But Italy has a storied history of masters of other fields, especially mathematics, science and engineering. In this blog series, we’ll take a look at a few of the influential renaissance men from The Boot who helped advance the fields of physics, chemistry, electricity, geometry, and more. These are the multi-talented renaissance men who tackled so many of the problems that now form the backbone of modern science, engineering, and technology. For this blog, I'll focus on Evangelista Torricelli (Figure 1), a 17th century mathematician, physicist. Torricelli was a contemporary of Galileo Galilei, and in fact carried on [...]
Figure 1: FEA mesh and shear stress results for a reinforced concrete slab © Glew Engineering Consulting, 2016 Finite Element Analysis Consulting (FEA) In this series of blogs on FEA, we will first cover some basic elements common to many FEA projects, and then in subsequent blogs in this series, illustrate those methods through examples. One of the services that Glew Engineering Consulting provides is finite element analysis consulting (FEA). FEA consulting has been a great boon to the engineering profession, allowing mechanical engineers and civil engineers to accurately model the stress and strain behavior of complicated parts and assemblies prior to building physical prototypes. FEA programs are capable of predicting the effects of loads and impacts, variations in temperature, changes in pressure, and [...]
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.