Finite Element Analysis: A popular vibration analysis technique

fBusinesses are constantly striving towards competitive excellence by trying to minimize any design and process related defects that hamper productivity. In fact business processes are becoming complex and organizations have to deal with important construction and infrastructural issues, vibration analysis services have assumed an important role.

FEA is perfect for evaluating the structural dynamic features of vibrating mechanical systems. The method is extremely important as it facilitates deeper understanding of why certain systems do not function as efficiently as expected. Besides, coming into use in case of failure, FEA is used to examine the dynamic features of machinery and mechanical structures before the process of fabrication.

To state very simply the technique involves a methodology that makes use of numerical formulas and algorithms for breaking down complex issues into simple finite elements that can be easily understood and resolved. Vibration analysis helps businesses diagnose, identify and resolve mechanical, engineering and structural issues at an early stage thereby aiding the quality of the manufacturing process.

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Vibration Analysis

Advantages of appyling FEA Thermal Analysis for Product Development

c2One of the most critical issues arising during design and development of temperature-sensitive objects/products such as aircraft wings, defense equipments or even telecom towers radio telescope is their performance in adverse conditions. For this a detailed analysis of temperature, stress and vibrations is required before sending the product for manufacturing.

Solution to such and similar problems is to take into account various peculiarities of product behavior by means of Finite Element (FE) Modeling. Previously this kind of analysis work was carried out using experimental methods for predicting the behavior of the component under required conditions. This method did allow analysis of the behavior under application of different external factors, but was very costly, time-consuming and sometimes practically not feasible.

In today’s competitive market of consumer products the development process at major engineering firms uses comprehensive FEA Modeling, Simulation and Analysis method replacing costly full-scale experimental method. FE modeling allows the developer to analyze behavior of the part under various external factors using virtual 3D models and simulations using Cad software such as Solidworks, HyperMesh, Nastran and ANSYS.

Better hardware and software infrastructure helps resolve complex spatial thermo-mechanical problems keeping in mind physical properties (such as temperature, radiation, vibration, etc.) and geometrical properties (such as large deformations, stress and kinematics) to get a solution in quick turnaround time. With the help of full-scale experimental method you can measure values in just hundreds of points whereas with FEA simulation you can consider thousands and millions of point for better precision and overall reliability.

FE Thermal modeling also helps you evaluate natural frequencies and related modes of the structure along with thermal stresses and temperature fields.

FEA Thermal analysis can be used for various loading types such as:

• Steady and transient thermal analysis
• Structural analysis under wind conditions
• Structural analysis under gravity conditions
• Structural analysis under seismic loading conditions
• Thermal Stress analysis
• Thermal Modal analysis
• Thermal Strain analysis
• Thermal Static/Dynamic analysis

Product Development

Courtroom FEA: But my expert has hand calculations

c1It is very important that design engineers do hand calculations. It is very important that engineering expert witnesses do hand calculations.

For everything but the simplest of part geometries, hand calculations of stress are generally rough estimates. Often they are only in the ballpark of the true maximum stress levels. Sometimes they are only in the ballpark of the average stress levels, and miss the highest stresses entirely.

In the span of 50 years, finite element analysis has gone from esoteric research topic to widely available, widely applied mature technology. In the 1980′s, FEA required extremely expensive mainframe computers, very expensive FEA codes and highly trained analysts, and was still implemented at many large corporations. In the 1990′s, Unix workstations provided distributed FEA processing and FEA packages went mainstream, lowering entry costs. A seat of hardware and software still cost many tens of thousands of dollars, and highly trained analysts were still required, and still FEA spread to thousands of companies. In the 2000′s, lower priced FEA packages run well on medium to high-end personal computers, and FEA usage continues to grow. Highly trained analysts are still needed to consistently obtain accurate results, a fact unfortunately ignored by too many in the industry.

Why does FEA usage continue to grow when all of these companies already have hand calculations? Because, when applied correctly, FEA works. It delivers accurate stress estimates for parts with geometry too complicated for hand calculations alone, which describes most of today’s parts. Accuracy means that localized stress concentrations can be removed. Accuracy means one less uncertainty, meaning that a lower factor of safety can be considered–resulting in lower weight, lower cost parts that are still stronger and have longer life cycles. Accuracy means that an expert witness can pinpoint areas of concern, and can often nail down the why’s and how’s of a part failure. As discussed in previous issues of Courtroom FEA, this will often point the finger at the responsible party, be it designer, manufacturer or end user. Accuracy can mean reduced lab testing by concentrating the investigation on the suspect areas. Accuracy means credibility.

FEA has internal checks that a good analyst needs to apply to verify the results. Hand calculations provide a rough estimate of the results, and the hand calculations and FEA had better match within their accuracies. If not, something is wrong with one or both of them, and the analyst had better correct that. Once they do match, hand calculations are an external check of the detailed FEA results. Hand calculations are good.

Expert FEA