Finite Element Analysis
Finite Element Analysis (FEA) is essential for analyzing complex pressure vessel geometries beyond standard design codes. It supports cyclic thermal loading, non-linear material properties, and impulse loads. Accurate 3D models and mesh densities are critical for precise results, especially in areas with high stress or temperature gradients.
FEA determines stress distributions under steady-state or transient thermal conditions, using brick-type models and stress linearization. Dynaflow Research Group specializes in FEA, adhering to ASME VIII div. 2 and EN 13445-3 codes, offering expertise across diverse components and scenarios.
FINITE ELEMENT ANALYSIS SERVICES
Advanced Engineering Analysis for Complex Industrial Equipment
Our advanced FEA techniques tackle intricate structures that defy conventional analysis methods. We specialize in modeling equipment under cyclic thermal loading, non-linear material properties, and impulse loads. By discretizing complex structures into finite elements, we accurately predict stress distributions, strain patterns, and potential failure points under various loading conditions.
We conduct comprehensive steady-state and transient thermal analyses to provide a complete picture of how thermal loads affect material behavior over time. Our expertise includes determining accurate stress distributions under various thermal conditions, from gradual changes to rapid thermal shocks. We excel in precise thermal boundary condition assessments, ensuring our models closely reflect real-world scenarios. This service is crucial for industries where temperature fluctuations are a constant concern, such as power generation and chemical processing.
This service addresses material failure under cyclic loading conditions, covering both high-cycle and low-cycle fatigue scenarios. For high-cycle fatigue, we employ advanced techniques to evaluate stress histograms against S-N curves, predicting failure in components subjected to millions of stress cycles below yield strength. In low-cycle fatigue scenarios, we utilize sophisticated elastic-plastic material models to accurately simulate material behavior. Our approach not only predicts potential failure points but also guides design optimization and maintenance scheduling.
Creep Analysis focuses on the time-dependent deformation of materials under constant load, particularly in high-temperature or high-pressure environments. Our analysis considers factors such as temperature, stress level, and material properties to accurately simulate the gradual deformation and potential failure of components over extended periods. This service is invaluable for assessing the integrity of critical equipment such as turbine blades, pressure vessels, and high-temperature piping systems.
Pressure equipment analysis ensures the integrity, safety, and compliance of pressure vessels and systems across various industries. Drawing on extensive experience with high-pressure heat exchangers and critical components, we employ advanced finite element modeling and stress analysis techniques to evaluate pressure equipment under extreme conditions.
Our approach adheres strictly to industry standards such as the ASME Boiler and Pressure Vessel Code and the Pressure Equipment Directive (PED) 2014/68/EU. We address common challenges in pressure equipment analysis, including material defects, corrosion, and design flaws, providing engineering managers with comprehensive insights into potential failure modes and optimization opportunities.
We determine accurate flexibilities and Stress Intensification Factors (SIFs) for specific components, enhancing the quality and reliability of pipe stress models. Our analysis covers scenarios including thermal expansion, pressure transients, and dynamic loads such as seismic events or fluid hammer effects. We employ sophisticated modeling techniques to account for non-linear effects, ensuring accurate predictions of piping system performance. This service is critical for industries like oil and gas, chemical processing, and power generation, where piping integrity is crucial for safety and operational efficiency.
We address the thermal performance and structural integrity of critical industrial components. We employ advanced thermal-fluid models to simulate heat transfer rates, fluid flow patterns, and temperature distributions within the exchanger. This analysis helps predict thermal performance, identify potential hot spots or dead zones, and optimize flow configurations. Simultaneously, we conduct detailed structural analyses to assess the mechanical integrity of heat exchanger components under various operating conditions. We evaluate thermal stresses, vibration effects, and fatigue life of critical elements such as tubes, tubesheets, and baffles.
Our Fitness for Service (FFS) checks evaluate the structural integrity and operational safety of in-service equipment with existing flaws or damage. We employ advanced FEA techniques to assess various damage mechanisms, including corrosion, cracking, and deformation, following industry-standard methodologies such as API 579-1/ASME FFS-1. Our process begins with detailed damage characterization, utilizing advanced non-destructive testing data to create accurate models of the equipment’s current condition. We then perform sophisticated stress analyses, considering factors such as operating pressures, temperatures, and cyclic loading.
Vibration analysis is a critical tool for ensuring the reliability and safety of industrial machinery and structures. We examine vibration signal patterns to detect, monitor, and prevent mechanical failures in a wide range of equipment, from rotating machinery to complex piping systems. Using sophisticated analysis software and finite element modeling techniques, we predict the performance of equipment under various dynamic conditions, including pressure surges and acoustic waves.
SYSTEMS WE CONDUCT FINITE ELEMENT ANALYSIS FOR
Advanced Finite Element Analysis for Critical Industrial Systems
Pressure vessels are systems designed to contain fluids under pressure, often subjected to high stresses and temperature gradients. FEA is used to ensure structural integrity, compliance with ASME VIII div. 2 or EN 13445-3, and to predict failure modes under extreme conditions such as high pressure or thermal loads.
Piping systems are industrial networks used in oil and gas, chemical processing, and power generation. FEA evaluates stress intensification factors, thermal expansion, pressure transients, and dynamic loads like seismic events or fluid hammer, ensuring safety and operational efficiency in critical piping infrastructure.
Rotating machinery includes turbines, compressors, and blowers. FEA is applied to analyze vibration patterns, fatigue life, and dynamic performance. It helps prevent failures caused by vibrations or cyclic loading, ensuring the reliability and safety of critical rotating equipment.
High-temperature components, such as turbine blades and high-temperature piping, operate under extreme thermal conditions. FEA evaluates creep behavior, thermal stresses, and long-term deformation, ensuring the integrity and performance of components in high-temperature environments.
FRP components are lightweight, corrosion-resistant systems used in various industries. FEA is used to analyze structural integrity, validate material properties, and investigate failure mechanisms, ensuring the reliability and performance of these specialized components.
Vibration-prone systems include machinery and structures susceptible to vibration-induced failures. FEA analyzes vibration patterns, dynamic conditions, and failure risks, ensuring the reliability and safety of equipment such as rotating machinery and piping systems.
Heat exchangers are systems used to transfer heat between fluids in industrial processes. FEA analyzes thermal performance, structural integrity, vibration effects, and fatigue life. It helps optimize flow configurations, predict thermal stresses, and identify potential hot spots or dead zones in critical components.
Heat exchangers are systems used to transfer heat between fluids in industrial processes. FEA analyzes thermal performance, structural integrity, vibration effects, and fatigue life. It helps optimize flow configurations, predict thermal stresses, and identify potential hot spots or dead zones in critical components.
Complex geometries involve non-standard designs or intricate structures that defy conventional analysis methods. FEA discretizes these structures into finite elements to predict stress distributions, strain patterns, and potential failure points under various loading conditions.
In-service equipment includes systems with existing flaws or damage, such as corrosion or cracking. FEA is used for Fitness for Service (FFS) checks, evaluating structural integrity, operational safety, and remaining life under current operating conditions.
Pressure equipment includes systems like boilers and high-pressure vessels. FEA ensures compliance with ASME and PED standards, evaluates material defects, corrosion, and design flaws, and predicts failure modes, ensuring safety and reliability under extreme conditions.
FINITE ELEMENT ANALYSIS APPLICATIONS
Finite Element Analysis Project Examples
When equipment is subjected to cyclic loading due to alternating process conditions, vibrations, pulsations, or daily startup routines, it has to be tested against the required ASME or EN codes for (high-cycle) fatigue and ratcheting (also referred to as low-cycle fatigue). Typical equipment where potential fatigue-inducing stresses are present are heat exchangers, boilers, separators, air coolers, compressors, etc.
High-cycle fatigue can lead to the accumulation of microstrain, crack initiation, or crack growth. Fatigue cracks will increase in size after each cycle until they eventually cause failure. Low-cycle fatigue or ratcheting on the other hand usually occurs after a limited number of cycles, typically smaller than 7000. Failure is caused by the build-up of plastic strain after each cycle.
Using FEA methods, both low-cycle and high-cycle fatigue can be assessed. For low-cycle fatigue typically an elastic analysis is performed. It however is also possible to perform this type of analysis with a plastic material definition where the actual build-up of plastic strain can be captured.
In a high cycle fatigue analysis, the operating cases between which the component cycles are considered. The acceptability of the resulting stress histogram is tested to conform to the applicable S-N or fatigue curve. The output shows the acceptable number of stress cycles. In some cases, the cyclic loads occur at elevated temperatures in the creep regime. In these cases, the combined creep and fatigue damage is determined according to API 579.
A fatigue analysis will aid in designing equipment for a given operational life. This analysis can also be approached from the other way around, though. When the equipment is already in use but shows some signs of wear or corrosion, a fitness for service (FFS) check can be performed. This will tell how long the equipment can still be operational under the current conditions. This type of analysis considers the expected past and future number of cycles.
When components are operating under a high temperature or pressure, it is important to understand the effect of creep deformations. Creep is the tendency of a solid material to move slowly or deform permanently under the influence of stress well below the yield strength. It is a time-dependent deformation that does not occur suddenly under the application of stress. Rather, it is the accumulation of strain as a result of long-term stresses.
The ASME or EN allowable for secondary stresses is higher compared to primary stresses. With an elastic-plastic (non-linear) material model, stress categorization is not required. Stress redistribution is captured in the material model. Incorporating the non-linear material properties of the materials thus provides a more accurate assessment.
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Hyperelastic materials like rubbers cannot be captured using a linear elastic analysis either. Although the deformation of these kinds of materials often stays within the elastic region, the stress-strain behavior is non-linear. With FEA this non-linear material behavior can be captured in detail. This increases the accuracy of the stress assessment
Usually, the results of a non-linear stress assessment are more optimistic because a more accurate material model is used. The safety factors to account for inaccuracies still apply, but are used to increase the applicable load, instead of reducing the allowable load.
A piping system generally ensures that a fluid is transported from one place to another. On this journey, it is not uncommon that the piping system contains some tee junctions or nozzles. According to ASME B31.3, the flexibilities and Stress Intensification Factors (SIF) should be analytically determined according to ASME B31J, unless you have more applicable data. Although ASME B31J SIF and flexibility formulas are determined based on fatigue tests and FEA, the accuracy of a piping model can be improved using the FEA of the specific components in the system. With FEA the exact geometry can be taken into account to determine the flexibilities and SIFs, thereby enhancing the quality of the pipe stress model.
The calculated temperature distribution can be used as a boundary condition in the FEA model, together with the other loadings such as pressure and nozzle loads. With an elastic material model, the calculated stresses need to be categorized, it needs to be considered which load is primary (or weight driven) or secondary (displacement limited). It is important to consider which loads should be combined, for instance, what is the range for the startup/shutdown, or the operating cycle, or does the pressure load always act simultaneously with the thermal loading?
Thermal analyses of heat exchangers are concerned with the determination of the heat transfer rates and fluid outlet temperatures for a prescribed inlet temperature, heat transfer area, and flow passage dimensions. This way the effectiveness of the heat exchanger can be judged and large temperature gradients, which may cause structural failure, are detected. To do so, it is important to identify the contribution of all heat transfer mechanisms to the total transfer of thermal energy. Conduction, through the structure as well as through air, radiation, and convection are considered.
Another aspect to be considered when deÂsigning or verifying heat exchangers is the performance over some time. Due to corrosion or fouling (the accumulation of undesirable substances on the surface, e.g. due to oxidation), the surfaces tend to acquire additional heat transfer resistance that increases with time, hence reducing the efficiency of the system.
Conventional thermal analysis calculations (HTRI) are performed using classic formulae where the heat transfer coefficients are determined using experimental relations. This approach has proven to yield reliable results for standard equipment. However, for unconventional designs, the reliability of such methods decreases rapidly.
Explosion shock waves are assessed as impulse pressure waves with an almost instant pressure rise. This fast pressure rise causes the DLF of an equivalent static pressure to be smaller than 1. The value of this DLF and the behavior of components loaded by explosive pressures can be assessed using FEA.
The fact that an impulsive load has a DLF smaller than 1, causes thin-walled pipe to be able to accommodate internal explosions with pressures that would cause pipe rupture if applied statically.
The fast application of explosive pressures also causes dynamic behavior of the equipment. Although the application is not repetitive in the sense that it can cause resonance, it does cause rippling in thin-walled piping similar to a transverse wave that occurs when moving the end of a rope up and down. In thicker pipes, the resistance to this rippling is larger and is less likely to occur. In the analysis it will be visible as an oscillating stress field, that does not cause plastic deformation.
Although piping and equipment can most likely accommodate explosive pressure, it will likely deform plastically beyond the point where it can continue its operation.
Assessment of potential internal explosion in H2-generation systems
Hydrogen generation equipment has an inherent risk for internal explosions, posing an issue to safety. The hydrogen piping and equipment are required to withstand internal explosions by limiting the damage to deformation. Although this disqualifies the component for future use, safety is not compromised.
For this project, DRG was tasked with finding a correlation between the data obtained from the explosion tests and simulations performed by the client and static pressure values that help prove compliance through static pressure tests.
