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Understanding the load-history of a product while it is in service is a great place to start when designing new products to be fatigue resistant. It is also a great place to start when performing a failure analysis or equivalent damage modeling. However, massive amounts of load-history data can quickly overwhelm most engineering analysts and managers.
The solution is to present load-history in another form that is simpler and easier to interpret. However, before the data can be presented in another form, the load-history must first be reduced into an array of stress-reversal cycles and counts. The process for reducing the load history is called rain-flow counting. The final output is a histogram of stress-reversal cycles.
In the graphics within this article, the load-history was reduced to an array of stress-reversal cycles through the process of rain-flow counting and then plotted in two histograms. The first is histogram of cycle ranges and the secondgraphic is a 3D range-mean histogram. The two plots are helpful for visually displaying the load-history. Based on the two one can interpret how stress reversal cycles are distributed during typical service. This information is critical for any type of fatigue or damage analysis.

Engineeringhelper offers data analysis and rain-flow (stress-reversal)counting services for data that was collected by your team or ours. Contact our professional engineering staff to see how we can help with your next analysis.

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The load products experience over time is known as the load-history. Load-history may be acquired by measuring forces, moments, and strains while a product is in service. Load-history is one of the most critical pieces of information for preventing product failure and/or performing a failure analysis.

Without knowing the actual load-history, engineers must assume loads based on limited information. These assumptions are rarely correct and lead to costly decisions. The cost comes in the form of sub-optimized products, poor performance, and high material cost. If products fail, additional losses will come back in the form of warranty and lost sales from dissatisfied customers.

Engineeringhelper offers full load-history collection service for any product in any environment (live, on site, or unattended data acquisition services). No project is too large or too small. Whether it’s in the lab, in the field, on the land, in the water or in the air, engineeringhelper can collect the load history needed to develop a complete understanding of how your products are being used.

Contact engineeringhelper now to assist with collecting the load history on your next project.

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Are you experiencing ongoing product warranty or quality issues? Do you have product or process failures? Are you lacking the critical information needed to implement permanent solutions? Are engineers and analysts struggling to give recommendations for permanent solutions? Are your engineers out of time?

Contact engineering helper for support in an emergency or to supplement capacity constraints. Engineering helper provides comprehensive failure analysis, risk assessment services and much more. Check out the complete listing of Professional Service Offerings.

Failure Analysis and Field Testing Services

Developing a full understanding of problem within context is the most critical step in the whole process. Engineering Helper will facilitate the problem investigation process. This includes identifying business needs, goals,and recommending a course of action.

Based on your needs, timing, and budgetary constraints, engineering helper will conduct a series of experiments through engineering analysis, FEA, lab testing or collecting field measurements.

Field and Laboratory Measurements

Measure and monitor your product or process anywhere at any time! Whether you need long term monitoring services or a just a quick measurement, engineering helper will devise a plan to suit the application and meet you needs. Test and measurement capabilities include custom instrumentation services and installation of virtually any sensor (strain gages, string pots, load cells, pressure switches, thermal couples, humidity, and much more). In addition, engineering helper offers complete field and laboratory data acquisition and data reduction services.

Analysis + Recommendations

New information will be fed back into analytical models and assumptions will be refined. Data and models will be analyzed and interpreted. Results will be presented in an easy to understand format - identifying all risks and assumptions. Finally,customers will be provided with a comprehensive list of recommended actions. Want more information? Email engineering helper now for a free consultation!

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