scholarly journals Fatigue strength of helical compression springs ‐ comparison of calculation methods according to DIN EN 13906‐1 and Forschungskuratorium Maschinenbau (FKM) guideline “Analytical strength assessment of springs and spring elements”

2021 ◽  
Vol 52 (2) ◽  
pp. 211-230
Author(s):  
T.J. Niwinski ◽  
M.B. Geilen ◽  
M. Klein ◽  
E. Sharma ◽  
J.O. Schommartz ◽  
...  
Keyword(s):  
Fatigue Strength ◽  
Calculation Methods ◽  
Strength Assessment ◽  
Compression Springs

A Comparison of Direct Calculation Approaches Applied on the Fatigue Strength Assessment of a Panamax Container Ship

2012 ◽  
Author(s):  
Zhiyuan Li ◽  
Wengang Mao ◽  
Jonas W. Ringsberg
Keyword(s):  
Stress Response ◽  
Fatigue Strength ◽  
Fatigue Damage ◽  
Measurement Data ◽  
Direct Calculation ◽  
Container Ship ◽  
Calculation Methods ◽  
Strength Assessment ◽  
Strip Theory ◽  
Calculation Procedures

Today, it is common practice to carry out fatigue assessments of ship structures using direct calculation procedures. A direct calculation analysis of a ship’s fatigue strength involves hydrodynamic analysis, stress response evaluation followed by fatigue damage calculation. Many numerical codes are available for these types of analyses. They could yield different values in a fatigue life prediction because of the different degrees of complexity in the computation of the ship’s response. For example, hydrodynamic loads can be calculated using the strip theory or the panel method. The stress response to these loads can be computed using a beam theory or more advanced analyses, such as global and/or local finite element analyses. In a direct fatigue analysis for ship design, spectral methods have been dominating but there is a growing interest in time-domain fatigue damage calculation procedures. The objective of the current investigation is to compare four commonly used direct calculation methods against measurement data. The comparison is carried out by making a case study on a Panamax container ship on which full-scale measurements have been performed. The computational efforts involved in the application of the current direct calculation methods are compared and their applicability in ship fatigue design is discussed.

Fatigue strength assessment of laser stake-welded T-joints subjected to reversed bending

2016 ◽  
Vol 39 (10) ◽  
pp. 1272-1280 ◽  
Author(s):  
D. Frank ◽  
P. Dissel ◽  
H. Remes ◽  
J. Romanoff ◽  
O. Klostermann
Keyword(s):  
Fatigue Strength ◽  
T Joints ◽  
Strength Assessment ◽  
Fatigue Strength Assessment

Fatigue Strength Assessment of a Butt-Welded Joint in Ship Structures Based on Time-Domain Strain Approach

2020 ◽  
pp. 1-16
Author(s):  
Yan Dong ◽  
Yordan Garbatov ◽  
Carlos Guedes Soares
Keyword(s):  
Residual Stress ◽  
Fatigue Strength ◽  
Time Domain ◽  
Welded Joint ◽  
Stress Strain ◽  
Ship Structures ◽  
Strength Assessment ◽  
Variable Amplitude ◽  
Notch Stress ◽  
Fatigue Strength Assessment

Fatigue strength assessment of a butt-welded joint in ship structures based on a time-domain strain approach is performed in this study. The service life load histories applied to the butt-welded joint located on the deck of a bulk carrier are generated, accounting for the still-water and wave-induced loads. The rainflow counting method is applied to analyze the load histories, and the long-term distributions of the load range are compared with those based on the conventional spectral fatigue analysis. An approach of converting the load history to a series of closed notch stress-strain hysteresis loops and several open notch stress-strain hysteresis curves is proposed and demonstrated under variable amplitude loading. The approach is based on analytical notch stress-strain estimations and consists of several steps to consider the material memory effect, overcoming some limitations of the existing methods. To determine the fatigue damage for the variable amplitude loading, a design fatigue curve is derived considering the uncertainty in the fatigue lives and load sequence effects. The intrinsic fatigue limit concept is used to filter the small amplitude cycles that do not have a damaging effect. The fatigue strength of the butt-welded joint is analyzed, taking the weld-induced residual stress and misalignment effects into account explicitly. The notch mean stresses or strain amplitudes of the cycles are significantly enhanced because of the presence of a high level of weld-induced tensile residual stress or misalignment, resulting in highly severe fatigue damage. 1. Introduction Complex ship structures containing geometrical and material discontinuities are prone to fatigue because of cyclic loads. Therefore, fatigue strength assessment has been an important criterion in the ship structural design (Guedes Soares & Moan 1991). Various fatigue design concepts for the assessment of welded joints, where fatigue failures mostly originate, are applied (Xu 1997; Radaj et al. 2006), and they can be classified into two types. The first one is based on S-N curves in combination with the Palmgren-Miner rule, and the second one is based on the crack propagation models and failure criteria.

Sign in / Sign up

Export Citation Format

Share Document