The critical distance is a geometric parameter used to describe the effects of notches on failure conditions under static as well as fatigue loading. Under fatigue loading, the critical distance depends on the number of cycles to failure, and it is determined from experimental data measured on smooth and notched samples. The results of the critical distance are influenced by stress concentration level as well as surface quality.

The fatigue resistance of AISI P20 + Ni steel mandrels with laser-cladded Al-bronze surface layers which are used for pipe bending is crucial for their service life. The article presents results of fatigue life measurement on four-point bending specimens manufactured from real mandrels. It was found that the renovation by re-cladding of the layer after mandrel wear results in an increase of fatigue life when compared to the new mandrel. The observed behavior (that has an economic impact) was explained and discussed based on microstructural features of the laser-produced surface layer, composed of two metallurgically well bonded materials and the microstructure and defects in the heat-affected zone of the base material.

The present study investigates the influence of corrosion exposure on the fatigue behavior of S460NL high-strength structural steel, a material that is frequently utilized in offshore and civil engineering structures. Accelerated corrosion was simulated under controlled laboratory conditions for exposure periods of 3 days, 6 days, and 6 + 3 days, in addition to specimens subjected to natural atmospheric corrosion. To this end, fatigue tests were performed to obtain S–N curves, and the results were evaluated using Basquin's law and the probabilistic Castillo–Canteli model. The findings indicate that corrosion has a substantial impact on fatigue resistance. The endurance limit exhibited a decline from 214 MPa for the reference specimens to 176 MPa following three days of corrosion, 135 MPa after six days, and approximately 92 MPa after combined corrosion exposure, signifying a reduction of up to 57%. Fractographic observations revealed that corrosion pits act as stress concentrators, thereby promoting early crack initiation. A discernible correlation was identified between corrosion mass loss and normalized endurance limit. These findings highlight the importance of considering corrosion effects in fatigue life assessment and structural design of high-strength steel components.

An experimental programme was undertaken to examine the fatigue response and visible damage location of welded S460 specimens following accelerated corrosion conditioning. Four initial surface states were considered: no corrosion exposure, 3 days of exposure, 6 days of exposure, and a combined 6-day plus 3-day intensified stage, designated 3D, 6D, and 6 + 3D/9D. Tension-tension fatigue loading was applied at R = 0.1. Selected welded regions were documented with an Olympus DSX1000 digital microscope after the assigned exposure and again following cyclic testing, with emphasis on visible surface alteration and fracture localization. Qualitative optical observations showed increasingly extensive visible surface alteration across the examined representative regions. The 3D specimen exhibited limited visible surface alteration, the 6D specimen showed more distinct corrosion-product regions and pit-like surface features, and the 6 + 3D/9D specimen showed the most extensive visible surface alteration among the four representative specimens. No quantitative surface-topography, pit-depth, roughness, or direct mass-loss measurements were performed on the welded fatigue specimens. The fitted S-N curves showed a non-monotonic ordering within the investigated dataset: the fitted curves for the 3D and 6D conditions were positioned above the uncorroded reference curve, followed by a lower fitted response for the 6 + 3D/9D condition. Because statistical differences among the condition-specific curves were not established, this ordering is interpreted only as a descriptive experimental trend. After fatigue testing, all representative specimens showed visible fracture localization near the weld toe and weld-adjacent region. Corrosion-related surface alteration was visible within the same welded region, but the qualitative optical observations do not establish the precise microscopic crack-initiation site or a causal contribution from an individual pit-like surface feature. The principal contribution is therefore the observation, in the four representative specimens, that visible fracture localization remained associated with the welded region across the investigated exposure conditions, while corrosion-related surface alteration developed within the same fatigue-critical area.

Cruciform welded joints made from thin S460NL high-strength steel plates were examined regarding their fatigue response under cyclic loading. An experimental and numerical framework was done, combining fatigue tests, finite element stress analysis, and Vickers hardness mapping. All fatigue experiments were performed at a stress ratio of R = 0.1. Numerical simulations showed stress amplification near the weld toe, while the hardness measurements showed welding-induced material heterogeneity throughout the joint. The study revealed a significant reduction in fatigue life for welded specimens relative to the base material, with the crack initiation frequently occurring near the weld toe. The findings highlight the significant impact of local weld geometry and metallurgical changes on fatigue performance in high-strength steel.

The present study investigates the development of fatigue damage in welded S460 high-strength steel specimens subjected to different corrosion exposure conditions. Four surface conditions were considered: an uncorroded reference condition, 3-day exposure, 6-day exposure and combined 6+3-day exposure, hereafter referred to as 3D, 6D and 6+3D/9D, respectively. Fatigue tests were performed at a stress ratio of . Microscopic observations were carried out before and after fatigue testing using an Olympus DSX1000 digital microscope to evaluate surface degradation, crack/fracture localization and damage development in the welded region.The uncorroded reference condition showed fatigue damage that was predominantly localized in the welded region, thereby confirming the dominant role of weld geometry and the local notch effect. As the level of corrosion exposure increased, the surface condition changed progressively. The 3D condition exhibited limited early degradation, the 6D condition revealed more distinct surface defects, and the 6+3D/9D condition showed the most pronounced corrosion-product regions and pit-like surface damage. The fatigue results indicated a non-monotonic influence of corrosion exposure. The apparent improvement observed for the 3D and 6D conditions may be related to local modification of the weld-toe surface condition and partial mitigation of the original weld-induced notch effect.After fatigue testing, all representative specimens showed crack/fracture development near the weld toe and heat-affected zone (HAZ) vicinity. The findings indicate that fatigue damage was governed by the combined effect of weld-toe geometry, the visually distinguishable HAZ vicinity and corrosion-induced surface degradation.

This paper presents the results of an experimental study with a focus placed on the long-term mechanical-, fracture- and fatigue analysis of mortar, in which natural aggregates (NA) were partially substituted with fine recycled concrete aggregates (RCA). Long-term tests were done at 28, 145 and 255 days under natural aging conditions. Fracture and fatigue experimental analysis took place for tensile mode I, which was enriched by fracture tests performed under a combination of tensile and shear load - mixed-mode I/II loading conditions. In total, four mixtures (reference and three with fine RCA) were tested to examine the influence of the aggregate replacement on the fracture and fatigue properties of the material. The experimental results showed that 25 % of replacement seems to be an optimum dosage of fine RCA, which improves both the fracture and fatigue properties of tested mixtures.

This paper contains results of a parametrical numerical study performed on an anchor/concrete system. Steel anchors subjected to tensile loading exhibit often so-called concrete cone failure and thus, investigations of this phenomenon are included in this paper. Maximum tangential stress distribution was investigated in the vicinity of a steel anchor embedded in a cylindrical concrete specimen. Finite element analysis enabled to analyze the dependence of both this value and the angle where it occurs on selected parameters, particularly the thickness of the anchor’s basement and the radial distance selected for the investigations. Results and their discussion are presented within this work as a part of an extensive research project on concrete materials and structures.

This article deals with identifying defects of layered high strength steel materials with the help of tomography measurement. Test samples were made of S960 High Strength Steel to which layers of either aluminium bronze, hardchrome, cobalt alloy or stainless steel were applied by a laser cladding technology. The experimental campaign included a study of morphometric parameters of internal defects in and near the bi-material interface region using X-ray micro-tomography and their potential influence on the fatigue behavior during a three-point bending test.

It has been published in recent research studies that several mechanical properties of mortar reinforced with suitably spatial shaped plastic elements can be improved. Thus, a hexagonal geometric shape was chosen due to its high rigidity for this study. Stress distribution at a bi-material interface between a polymer part reinforcing a mortar specimen and the rest of the mortar part has been investigated to explain fatigue fracture behavior of rectangular specimens tested. A three-point-bending (3PB) test was simulated via a finite element method (FEM) considering several simplifications, and various heights of the polymer reinforcement were modeled to investigate its influence on stress redistribution. For comparison, a pure mortar specimen without any plastic elements was considered the reference. The numerical results obtained are discussed and compared to the experimental ones. Within the experimental campaign, bulk density, static properties and fatigue characteristics were tested, analyzed and discussed. Improvements in flexural strength were observed when the plastic panel was used as reinforcement, which agrees with other scientific works. Directions for future research were identified.

The subject of the study presented in this paper is to quantify the effect of fiber content on the mechanical and mainly fatigue response of fine-grained cement-based composites. The reference cement-based composite was without fibers. Three types of fibers were used as dispersed reinforcement: tire cords (waste material), steel, and polypropylene. For each type of fiber, mixtures with varying reinforcement levels per volume were prepared: 0.0 % (reference composite), 0.5 %, 1.0 %, and 1.5 %. Prismatic specimens 40 mm × 40 mm × 160 mm were prepared and tested. A total of 10 composite variants were investigated. The ages of the specimens for the static three-point bending tests were 28 days, for the compression tests were 28, 120, and 275 days. While for the fatigue tests, it was approximately between 110 and 180 days. The obtained compressive strength values for the above-mentioned composite ages were approximated by a selected exponential function and the results of the fatigue tests were standardized to a nominal age of 28 days using them. All used types of reinforcement increase the strength values of the composites even from the lowest fiber doses. A positive effect of fiber dosage above 0.5 % on the fatigue behavior of composites was shown only in the case of reinforcement with commercial steel fibers.

The work is devoted to investigations of the stress distribution/concentration in a corroded specimen loaded via remote tensile loading. Existence of corrosion pits of various size and various mutual distance affects stress distribution in a specimen which can have influence on its lifetime. Thus, numerical simulations via finite element method were performed in order to assess the stress field near corrosion pits in specimens made of high-strength steel. The geometry of the numerical model was suggested based on the dimensions of the real specimens produced for fatigue experiments. The results obtained are discussed and mutual comparison with experimental data is intended in oncoming months.

Our study utilizes a range of cumulative fatigue damage models to better understand the behavior of high-strength steels, addressing some of the shortcomings in current methodologies.To achieve this goal, a series of mechanical tests were performed on two types of HSS, S690, and S960, to understand the properties of these materials and determine their effect on the ability to resist fatigue damage.The accuracy of each model is determined based on the fatigue tested and S-N curves formed.The results are analyzed to determine which models are appropriate for predicting the fatigue behavior of high-strength steels.Overall, this study provides valuable insight into the fatigue behavior of HSS and highlights the need for further research in this area.By expanding our understanding of the properties of HSS, we can continue to develop new and innovative ways to utilize this material in construction, ultimately leading to safer and more reliable structures.

Exploring S460 steel, this research assesses weld toe microstructure and fatigue. It finds that welding affects hardness of welded area and fatigue life. These insights are crucial for structural engineering, optimizing welding practices for longevity. Tests confirm increased weld toe hardness correlates with fatigue resistance. This informs design strategies, ensuring bridge safety under cyclic loads. The study advances understanding of HSS behaviour, influencing future welding techniques.

Propagation of a short fatigue crack directly from a corrosion pit is investigated within this work. A corroded rectangular specimen subjected to remote tensile cyclic loading is modelled via finite element method. Propagation of the angled crack is then controlled by both loading modes (I + II). A parametric study is performed to estimate the directions of further crack propagation for various geometrical configurations. Corrosion pit size is varied to simulate various levels of corrosion, and the analysis is carried out for a range of crack lengths and different initial crack inclination angles. Assumptions of linear elastic fracture mechanics are accepted, and classical maximum tangential stress criterion is applied to calculate the angles of crack deflection. Results obtained are discussed and are prepared to mutual comparison with observations of decrease of fracture mechanical/fatigue properties on real specimens subjected to relevant experiments.

Both fatigue and corrosion are two phenomena that can be very often found in metallic components. Thus, it is necessary to study their mutual effect. In this paper, a high strength steel specimen was modelled via finite element method in order to investigate the interaction of a fatigue crack and a corrosion pit. Particularly, a rectangular specimen with a corrosion pit and a nearby angled crack under remote tensile loading was modelled and the crack deflection angle was investigated via MTS and SED criteria for various crack lengths and various crack inclination angles. The results obtained clearly show how the crack behavior is affected by the presence of the corrosion pit.

In this work, results of a numerical parametric analysis are presented in order to compare them with experimentally observed concrete cone failure features. Such a kind of failure is typical for cast-in steel anchors embedded in concrete substrates. Thus, numerical simulations via finite element method have been performed in order to investigate basic fracture parameters for specimens with a short fatigue crack and stress distribution for specimens without any crack. Several parameters were varied and their effect on the stress intensity factors or distribution of stress tensor components around the anchor corner were studied and discussed. Slight differences between the average angle typical for concrete cone failure observed experimentally and numerical results were found out and thus, more complex numerical simulations shall be recommended.

This study evaluates the fatigue life of S960 high-strength steel with laser-cladded layers of aluminium bronze, hard chrome, cobalt alloy, and stainless steel, using three-point bending tests. Our results demonstrate that while these cladded layers offer potential for enhanced surface properties, they generally reduce the material’s fatigue life due to alterations in the heat-affected zone and the introduction of microstructural defects at layer interfaces. The extent of fatigue life reduction varies with the type of cladded layer, highlighting the importance of optimizing laser cladding parameters to minimize detrimental effects and improve component longevity.