Strength Calculation in General
We typically perform strength analysis as part of a larger mechanical design project, but in some cases, we carry out standalone strength assessments. In these situations, the client usually has strong design resources in core competencies but may lack the resources for strength analysis.
We typically use Finite Element Method (FEM) analysis, employing software such as Siemens' Femap and Autodesk Inventor's built-in FEM tool, depending on the nature of the task, for solving more complex strength analysis problems. Additionally, we also perform strength analyses using analytical methods.
"Steel structures are designed primarily according to Eurocode standards. Lifting equipment can be calculated according to standards such as EN 13155, and the calculation of components for pressure equipment is typically carried out following the guidelines of the Pressure Equipment Directive (PED) (EN 13445).
The outcome of a strength analysis project always includes a report for either the client's or the inspection authority's use. The report highlights the key results of the conducted analyses, the methods employed in the calculation, and any suggested improvements if they were not already incorporated into the plans during the project.
Finite Element Method FEM
We efficiently solve problems related to complex structures and phenomena using the finite element method in cases, where using traditional analytical methods is practically impossible. The finite element method allows modeling the behavior of a structure in various situations. We can impose forces and constrained displacements as loads on the structure, or the loading can result from factors such as thermal expansion or accelerations due to rotational motion, all of which can be accurately simulated using the finite element method.
We have conducted various static and dynamic strength analyses for lifting equipment, crane beams, equipment lifting scenarios, load-bearing steel structures, process equipment, and rotating machine components. We have expertise in fatigue analysis, especially for welded joints, and we are happy to provide recommendations for both structural modifications and manufacturing techniques to improve the fatigue life of the product. Additionally, we have used the finite element method to solve deformations caused by asymmetric shrink-fit joints in shape- and dimension-critical applications.
Typical Strength Calculation Cases
- Solving displacements, loads, and stresses of complex or statically indeterminate structures, such as a lifting scenario during an installation of a silo component or a strength of an electric motor rotor, involves advanced analysis techniques.
- Handling nonlinear phenomena, such as material non-linearity, large displacements, or modeling contacts, is crucial for scenarios like snap-fit connections, plastic capacity, or preloaded bolted joints with multiple fasteners.
- Analyzing structural vibration and other dynamic phenomena, such as determining the natural frequencies of a structure and defining sufficient stiffening to prevent structural vibration, involves dynamic analysis techniques.
- Calculating local stresses, such as in fatigue analysis of welded joints, involves determining structural stress (Hot-Spot) or effective notch stress (ENS) using the finite element method, enabling the estimation of the joint's lifespan.
- Structural instability phenomena, such as buckling of plates or shells, instability in thin plate structures, and the lateral-torsional buckling of slender statically indeterminate beams, require advanced analysis techniques to predict and mitigate.
High-Speed Machinery
In addition to static structural analysis, we have also calculated the durability of dynamic components in various scenarios. A typical case is calculating the maximum stresses and displacements induced by the high-speed rotation of a turbine impeller at different locations within the structure. Based on these calculations, we can determine the appropriate material for the rotating part and modify the geometry to alleviate local stress peaks.
The design of high-speed machines often involves various thermal analyses, such as thermal expansion considerations, sizing of shrink fits, and assessing their endurance under high speeds and temperatures.
We have also conducted other technical calculations for high-speed machines, such as estimating bearing lifespan, calculating leakage in labyrinth seals, determining axial forces in compressors, and performing rotor dynamic analysis.
Janne Savolainen
Structural Analyst
Feel free to ask our expert any questions related to strength analysis!
firstname.surname@mertalainnovations.fi
050 911 7618
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