Specialist durability result types

Specialist Durability Plots (SDP) scenario lets you view the following specialist durability result types as 3D contour plots. For more information, see Specialist Durability Plots scenario.

• Maximum, minimum, and mean stress, and maximum amplitude stressThe stress life analysis type uses the pseudo stress, and the strain life analysis type uses the real stress. The stress value is calculated from the uni-axial equivalent stress, such as Von Mises, or the critical plane approach.If the local stress state is an equivalent stress, such as signed von Mises or max shear, the time history of all these equivalent stresses is included in the analysis, to identify the maximum and minimum stress. In most cases, the software sets 0 as the time history starting point.If the local stress state is calculated from the critical plane approach or any approach that uses more than one local stress state, the maximum and minimum stress are the maximum and minimum stress of all directions. The maximum and minimum stress can occur in different directions so that (maximum-minimum)/2 does not necessarily coincide with the maximum stress amplitude.Max. StressThe maximum stress encountered during the loading.Note: For a model under random excitation, there are two methods to compute the maximum stress, depending on the estimation method of the random load probability distribution. Equivalent sine wave is a simple deterministic method that calculates an equivalent sine wave excitation of the load distribution. The sine wave has a maximum amplitude and a maximum stress. For Dirlik and narrow band methods, computing the maximum stress is not as simple because these two methods are probabilistic. This means that load cycles of any amplitude may appear in each sample, and the probability that they appear decreases with the size of the amplitude. Therefore, for an estimation of a maximum stress, the duration of the signal is required. The maximum stresses would occur during the fatigue life time of the model. The longer the fatigue life time of the model, the higher is the probability that large stresses occur in that fatigue life time. Specialist Durability predicts the maximum stresses such that with a probability of 50%, the stresses remain below the given maximum stress in the fatigue life time of the model. Half of the samples predicted by the cycle distribution contain stresses that do not exceed the given maximum stress in the entire fatigue life time of the model, and half of the predicted samples exceed the given maximum stress during the fatigue life time.The maximum stress is also used in the calculation of the static failure.Min. StressThe minimum stress encountered during the loading.Mean StressThe mean stress of the largest stress cycle in the most damaging critical plane direction. This result is used for safety factor calculations.Max. Amplitude StressThe maximum stress amplitude encountered during the loading.

• Cyclic Fatigue DamageFatigue damage is represented as the Miner sum of the individual damages of damaging load cycles. It accumulates from 0 (no damage) to the Miner sum of the complete load time history. The SPD scenario displays the Miner sum.If the damage sum limit that you define in the Damage Sum Limit simulation object is set to 1.0, the Miner sum is 1.0 / (number of sustainable repetitions). If you define another damage sum limit, the Miner sum is (damage sum limit) / (number of sustainable repetitions).Note: Because failure occurs when the Miner sum exceeds the damage sum limit, the number of sustainable repetitions linearly depends on the damage sum limit. Therefore, the cyclic fatigue damage result is independent of the damage sum limit.Note: When the contour plot includes locations where the static failure occurs, the SDP scenario displays the static failure with a cyclic fatigue damage value of 100.

• Fatigue LifeThe number of sustainable repetitions of the complete load time history. If the load corresponds to N km, the estimated fatigue life corresponds to (fatigue life) x N km.

• Fatigue Life TimeThe time to failure that is calculated as the loading duration multiplied by fatigue life. You define the loading duration of one block of load when you create a durability load event.

• MileageThe equivalent running distance to failure that is calculated as the load corresponding riding distance multiplied by fatigue life. You define the load corresponding riding distance of one block of load when you create a durability load event.

• Design Life FactorThe ratio of the design life value and the computed life. You define the design life in the Design Life simulation object.

• Design Load FactorThe factor by which the load must be divided to reach the design life that you specify in the Design Life simulation object. A design load factor smaller than one is the inverse of the margin of safety. Note: If the design life is set to the number of cycles at endurance limit, the design load factor is also called the “Degree of Utilization.”From the computed fatigue life, the software can re-calculate the corresponding stress value (S) using the SN curve. This stress represents the amplitude for a constant amplitude loading, which causes the same damage. The load design factor is the ratio of (S) and the design stress (SD), which is calculated from the design life using the SN curve. In the strain life analysis type, the SN curve is synthetically calculated. The S/SD ratio is used as an estimate for the design load factor.

• Stress Reduction FactorThe SPD scenario displays the local stress reduction factors. For more information, see Theoretical concepts.

• Safety FactorThe factor that can be applied to the loads to reach the endurance and static limit. For example, a factor of 2 means that the load does not cause any damage as long as it is scaled with a factor smaller than 2 and the damage starts when the factor is larger than 2. To determine the safety factor, the software first calculates the factors for static failure and fatigue failure.Static safety factor = tensile strength / maximum stressFatigue safety factor = endurance limit / maximum stress amplitudeCombined safety factor is the minimum of the static safety factor and the fatigue safety factor.These results depend on the method that the software uses to calculate the local stress because the values for the maximum stress and the maximum stress amplitude depend on the selected method (such as signed von Mises, maximum principal stress, and critical plane).

• Maximum and minimum temperatureThe maximum and minimum temperatures of load history during durability analysis.Max. Temperature****Min. Temperature

Quick links

Specialist Durability Plots scenario

Command reference

Pre/Post video examples

Bulk Entry Descriptions

Simcenter 3D tutorials

Browse Simcenter 3D help by product area

Specialist durability result types, Simcenter 3D 2021.1 Series

© 2020 Siemens

window.mainLanguage="en_US"

window.delivId=""

window.projectId=""

MathJax.Hub.Config({ TeX: { extensions: ["autoload-all.js"] }, tex2jax: { displayMath: [ ] }, "SVG": { scale: 125 } });