Monthly Archives: July 2015

Forensic Engineering and Failure Analysis

posted July 2015

Some of the most interesting and challenging projects at MEE are the forensic engineering cases. Forensic engineering is application of engineering principles to the investigation of incidents that have or may lead to litigation or other dispute resolution venues. Engineers at MEE practice specifically in the areas of forensic metallurgical engineering or forensic materials engineering. This work typically involves the investigation of failures in structures, products, or components in support of product liability litigation. Our expertise in materials behavior and failure analysis make our staff well qualified for these investigations. The emphasis that we place on clear communication of our findings to our industrial customers serves us well when our engineers are asked to assist the court by testifying in deposition or a trial.

Go to our website to see  a short list of  forensic engineering cases at MEE

Fatigue fracture of improperly-repaired truck trailer side rail

Fatigue fracture of improperly-repaired truck trailer side rail

 

Filed under: About MEE, Failure Analysis, Fatigue Failure, Forensic Engineering,

Preparing Samples for Metallographic Examination

posted July 2015

Not all of our projects come to us in small packages. How do we get that 7′ long, 6″ diameter steel tube or the 4′ diameter industrial fan under a microscope?
Sample preparation often begins in our machine shop. The MEE shop is equipped with a variety of cut-off saws, a Bridgeport mill, plasma cutter, band saws, and other specialty tools necessary to cut out representative sections from large pieces for further preparation before a metallographic and/or microscopic examination.
Before any cutting is done, it is crucial to understand that proper sample preparation methods are necessary for accurate materials analysis. Care must be taken when cutting a sample from a larger piece to not contaminate or alter the area of interest.
If you have questions about sample preparation, preservation or handling, read MEE’s ten commandments of sample handling and preservation in our online Handbook of Analytical Methods for Materials.

Our hands-on expertise extends outside the microscopy lab.

Our hands-on expertise extends outside the microscopy lab.

Filed under: Materials Characterization, Materials testing laboratory, metallography, microscopy,

Variable Pressure SEM vs Field Emission SEM

posted July 2015

Two types of modern scanning electron microscopes provide the range of sampling handling and resolution needed for evaluating most samples – the variable pressure SEM (VPSEM) and the high-resolution field emission SEM (FESEM). At  MEE, we offer SEM services with both types of microscopes to meet almost every challenge.

The VPSEM is a workhorse for routine work, but magnification is not adequate for observing the smallest features that we often need to see. With a much brighter electron source and smaller beam size, the FESEM increases the useful magnification range for observation and imaging up to 500,000X.

MEE is one of the few independent materials characterization labs in the Upper Midwest offering both variable pressure and field emission scanning electron microscopy.

These images provide  a comparison of VPSEM and FESEM operating under similar conditions on the same thin film sample.

vpsem

Variable Pressure Scanning Electron Microscope 34000X

fesem

Field Emission Scanning Electron Microscope 34000X

 

Filed under: Materials Characterization, Materials testing laboratory, scanning electron microscope,

Failure analysis case studies

posted July 2015

Stress corrosion cracking in a chemical storage tank, hydrogen damage in a boiler tube, fatigue fracture in titanium sternal plates are just a few of the case studies on our website.   They were specifically chosen to highlight the variety of projects we see in our laboratory and more importantly, demonstrate the thorough, analytical approach we take on all of our projects.

Engineering Consulting_Failure_

Blade failure on wind generator

The goal of a failure analysis is to determine the how and why of a failure.  Laboratory testing at MEE, which may include scanning electron microscopy, Rockwell hardness testing, corrosion testing,  and metallographic evaluation  can help us get answers to the how and why but we also like to work with our client to answer the question of “now what”  in order to minimize future risk of failure.

 

 

Filed under: About MEE, Case Studies, Failure Analysis, Fatigue Failure, hydrogen embrittlement, metallography, microscopy, scanning electron microscope, stress corrosion cracking,