In this study, a novel printed circuit board (PCB) strain-based structural design methodology for spaceborne electronics was proposed to compensate for the drawbacks of the conventional Steinberg’s theory. In addition, finite element modeling technique based on strain-based theory, which provides a reliable and rapid solution to structural design of electronics, was investigated. The effectiveness

The paper presents a new fatigue damage assessment model defined for the strain energy density parameter. The model is defined for calculations in the frequency domain for the case of narrowband loading. Analytical expressions are derived for the probability density function of peaks, the level crossing spectrum, and for the expected damage that is directly linked to the power spectral density of the

This paper examines the effect of mean stress on the fatigue behavior of very hard carburized steels. Current theories suggest that the maximum stress at the fatigue limit continuously decreases with decreasing minimum stress whereas the results of this study indicate that the maximum stress remains constant for minimum stresses less than the fully reversed constant amplitude fatigue limit minimum

Historically, S-N curve has been expressed in the form of an exponential relationship between applied stress σ and number of cycles to failure Nf. This paper elucidates the essential structure of S-N curve based on the prediction method for fatigue life and limit of materials containing defects from the viewpoint of mechanics of small crack. The extended application of the proposed method to step loading

Dent-repaired fatigue performance of thin sheet specimens under coupled multi-stage damage with impact and pre-fatigue was investigated. Different damage combinations of fatigue, impact and repair were performed to simulate actual service of aircraft. Residual fatigue life after repairing is 27.8% higher than that of unrepaired, axial strain field during fatigue loading is redistributed after repairing

A series of 2IML multilayer coatings (composed of two hard intermetallic (IML) layers and two soft sublayers) with the different thickness of the first IML sublayer have been built to develop our mechanistic understanding of what controls its fatigue performance. Experimental investigations of these multilayer coatings reveal that decreasing the IML-Top layer’s thickness provides improved fatigue resistance

This study investigated the effects of cyclic nonlinear viscoelastic (NLVE) loads on the fatigue response of asphalt binder, and the damage accumulation law of asphalt binder under NLVE-LVE combined loads. The experimental results reported the difference in the fatigue characteristics of asphalt binder under cyclic NLVE and LVE loads. It was found that NLVE loads nonlinearly reduced the remaining fatigue

Foreign object damage (FOD) introduced in service, indentations, and nicks encountered during maintenance are typical defects leading to pre-scrap of high-speed railway axles. A comprehensive assessment of the influence of these defects on the structural integrity of axles is critical for ensuring their operation safety with low maintenance costs. Three types of defects were produced artificially on

A novel high-frequency testing methodology for small thin-walled component like structures is presented that enables fatigue tests up to 1e9 cycles within 7-8 days. A shaker excites the designed thin-walled (min. 0.1 mm) specimen near its resonant frequency and a non-contact relative displacement measurement allows to set a defined notch stress. Calculated and experimentally determined resonant frequencies

Ductile failure under ultra-low cycle fatigue (ULCF) loading is often the limit service state of a nuclear structure. In the paper, ULCF tests for a C-Mn-Si steel are carried out. It is observed that the fracture displacement decreases as the number of fatigue cycles increases. An energy-based model, which considers the effects of both stress triaxiality and cyclic loading on the critical fracture

This work investigates the quasi-static, low-cycle and fatigue behavior of hybrid glass/ultra-high modulus carbon (GC) and low modulus/ /high modulus carbon (CC) fiber composites. These pseudo-ductile unidirectional interlayer hybrids are a new type of composites whose potential is not yet fully understood, particularly under cyclic/fatigue loading. Different test methods (digital image correlation

Spectral analysis constitutes an essential technique for random vibration fatigue. The power spectral density (PSD) provides an efficient, statistically unique characterization of stationary Gaussian loading which can be effectively processed via linear systems theory and load-spectrum estimators such as the Dirlik formulation. The PSD represents vibration loading by its averaged intensity for frequency

Laser directed energy deposition repair provides significant advantage over current grind-out repair methods for 300 M steel, with samples containing 40% deposit producing equivalent low cycle fatigue behaviour to unfilled 10% grind-outs, though with reduced tensile strength. High cycle fatigue is associated with crack initiation at defects or locally softened regions due to in-situ tempering. While

This study discusses the creep-fatigue life prediction of eutectic Sn37Pb solder. Creep-fatigue lives were experimentally obtained at 313 K using fast-fast, slow-slow, slow-fast, fast-slow, and strain-hold waveforms. Conventional four creep-fatigue life prediction rules, time fraction rule, strain range partitioning method, frequency modified fatigue life, and ductility exhaustion model was used to

The linear amplitude sweep (LAS) test is considered a useful tool for evaluating fatigue of asphalt binders. It has been confirmed that a good correlation exists between fatigue performance of binders and mixtures in a few studies. While the change in binder fatigue with load or strain level is well studied and modeled, the effects of oxidative aging remain difficult to explain or to model in a simple

Fatigue life analysis and FEA require high computational costs for aerospace models. Goodman diagrams are useful tools for determining the fatigue life of a part, and depend on structural and modal FEA simulations. Surrogate models have been used in fatigue analysis to predict the steady stresses and alternating stresses FEA model for every par node enabling a dynamically-updated Goodman diagram that

Three types of commonly used local stress approaches recognized by Codes and Standards for fatigue of welded joints are reviewed and evaluated with respect to a comprehensive collection of multi-axial fatigue test data available in literature. These local stress approaches are surface-extrapolated hot spot stress, effective notch stress and traction structural stress. The hot spot stress and notch

Fatigue performances of an in-situ TiB2 particle reinforced 2024-T4 alloy matrix composite (TiB2/2024Al) and 2024-T4 aluminum alloy (2024Al) were investigated. Stress- and strain-controlled fatigue experiments were conducted to obtain the fatigue lives. High-cycle fatigue performance was experimentally studied under different stress concentration levels. The results showed that the addition of in-situ

This article describes investigations into the subject of load assumptions on a self-propelled forage harvester. A measurement campaign during the maize harvest in hilly regions in Germany and the corresponding evaluations are presented. The investigations analyse both the usage profile of the machine and the load data for the chassis. The used sensors enable the acquisition of wheel forces and moments

Strain-controlled Low-Cycle Fatigue tests (LCF) and Thermo-Mechanical Fatigue tests (TMF) were performed on a low-alloy martensitic steel in the temperature range between 300 °C and 600 °C, with and without a strain dwell. TMF tests were performed for three different phase angles between thermal strain and mechanical strain: as in-phase, as out-of-phase and as counter clockwise-diamond. The results

The adaptability of steel 45 to low-cycle deformation from 100 to 1000 cycles at different constant strain amplitudes, characterised by the effect of plastic-strain stabilisation, is considered. In this study, the proposed structural–temporal model of cyclic deformation simultaneously predicted the stress-strain dependence and the effect of plastic-strain stabilisation based on hysteresis width. Experiments

Gradient nanostructured (GNS) layer was fabricated on the pure titanium using ultrasonic surface rolling process. With the coaction of deformation twinning, phase transformation, and dislocation slip, a spatial gradient of grain size distribution was formed. Nanocrystalline and amorphous phase exist simultaneously on the top surface. The effect of grain refinement, dislocation density, and deformation

Failure of materials subjected to torsional and axial cyclic loading is studied by applying the principles of thermodynamics of dissipative processes. Extensive experimental tests are conducted using stainless steel (SS) 304 and SS316 materials to gain insight into both torsional and tension–compression fatigue life. It is shown that the higher magnitude of dissipated energy in torsional loading, as

In present study, the fatigue crack growth (FCG) behavior of commercial pure titanium (CP-Ti) at negative load ratio with a single tensile overload was investigated through the combination of experiment and finite element method (FEM). The influence of load ratio and overload ratio was considered to investigate the overload retardation effect of FCG with compact-tensile-shear (CTS) specimens. Changes

A multilayer coating system containing two hard intermetallic layers (IMLs) within a soft metallic system provides improved fatigue performance. To further optimise this system, various coatings with different locations of the intermediate intermetallic (IML-Top) interlayer were manufactured and experimentally investigated. Their characteristics were assessed and fatigue performances were compared

Durability engineering for vehicles is about relating the real operational loading and fatigue environment to the actual capability and strength capacity of the product and its parts. The statistical modelling of the usage loading distribution has always been a big challenge; the latter is necessary to derive statistically validated design targets. In the past, dedicated durability measurement campaigns

This article concerns the experimental and numerical study of post-impact damage propagation in thin carbon/epoxy woven composite laminates loaded in fatigue tension. Low velocity normal drop weight impact tests are first performed. Post-impact fatigue tensile tests are then carried out. They are controlled in displacement. The monitoring is based on Digital Image Correlation and RX tomography. The

Mean stress effects on fatigue life of a stainless steel in air and boiling water reactor (BWR) environments were evaluated by load-controlled tests. In stress-life, non-zero mean stresses increase life in low cycle fatigue regime in both environments and in high cycle regime in air. In high cycle fatigue regime in BWR environment, higher fatigue life was observed with negative mean stress while a

An investigation into the effects of overload mode-mixity on crack growth behavior and governing micromechanisms of AA7075 T6 has been conducted. Cruciform AA7075 T6 specimens were subjected to constant amplitude planar biaxial fatigue with single overloads, and key fatigue damage behavior, including fatigue life, crack growth rate, and recovery distance, were investigated and correlated to overload

In this paper, multiaxial fatigue experiments on a hyperelastic rubber-like material made of polychloroprene rubber (CR) reinforced with tungsten nano-particles have been carried out on notched specimens and hourglass specimens, utilized for limiting dome height fatigue tests. Based on the uniaxial [1] and multiaxial fatigue experiments, a semi-empirical ε-N fatigue model is proposed, allows accounting

Ambient and Hot Compressive Dwell (HCD) fatigue experiments were carried out to understand the effects of HCD on the fatigue crack growth behavior of cast 319 Al and Inconel 718 engine alloys. HCD was found to reduce endurance and increase rates of crack growth at engine service temperatures, while far less crack growth acceleration was found at room temperature. A fracture mechanics-based model was

The present paper is devoted to rapid prediction of fatigue performance of materials for medium- and high-cycle fatigue based on the thermography approach. During cyclic loading, the temperature of specimens or components increases due to both anelastic and plastic deformation, while only the plastic strain energy contributes to fatigue damage. Therefore, in this work, a model is proposed to estimate

The high-cycle and very-high-cycle fatigue (VHCF) behaviors of AlSi10Mg alloy produced by additive manufacturing (AM) were studied. A crystal plasticity finite element model (CPFEM) with Voronoi tessellation was developed to simulate the cyclic plastic deformation considering defect effects. Morrow’s model and Smith-Watson-Topper (SWT) model were used to predict the fatigue life and the SWT model was

Subsurface crack networks surrounded by microstructural alterations, named as “White Etching Cracks” (WEC), lead to wind turbine gearbox bearing (WTGB) premature failures. This phenomenon has been studied for decades without yet reaching a sturdy and justified cause of its occurrence. This paper reviews the most recent literature regarding WEC discussing steel microstructural alterations, WEC initiation

A mode II delamination growth rate model was constructed using constant amplitude fatigue data from mode II displacement-controlled testing, for the purpose of failure prediction. Unidirectional precracked composite coupons were tested using a fully reversible three-point bending fixture. Using a series of constant amplitude delamination growth rate data, the growth of delamination propagation under

This article develops a theoretical approach to account for the uncertainty of the fatigue damage caused by the sampling variability of a power spectral density estimated from a finite length stationary record. The moment generating function of the estimated spectral moments is obtained and used to approximate their probability distribution with that of a chi-square random variable with a newly chosen

In this paper a method is presented to combine incremental notch approximation methods for multiaxial cyclic loading with a cyclic plasticity model. The proposed solution algorithm improves the numerical stability of incremental notch approximation methods. This allows a load path to be discretised with few increments thus the computational effort is lowered. The proposed method is used for three known

The objective of this work is to analyze the high-cycle fatigue performance of the corroded base material without joints. Constant-amplitude axial tensile fatigue tests were conducted on 55 specimens obtained from the various environments. The infrared thermography was used to track the surface temperature of the specimens. When the corrosion degree is close, the accelerated corrosion test can simulate

Two distinct and different unimodal γʹ size distributions have been produced in a disc alloy RR1000 to understand the combined effects of γʹ size (linked to slip character), grain boundary (GB) precipitates/carbides and dwell time on fatigue crack growth (FCG) mechanisms at elevated temperature. The FCG behaviour has been investigated on single edge notched bend samples of both γʹ variants at 650 °C

Injection moulded short fibre reinforced composites (SFRC) have variable fibre orientation distribution at every point and are often subjected to multi-axial fatigue loading due to their inherent anisotropic nature. The fatigue properties are known to be significantly dependant on the fibre orientation distribution. Thus, the fatigue simulation of SFRC components poses dual challenges of predicting

To explore the fatigue fracture behavior of self-compacting concrete (SCC), constant amplitude loading tests and incremental amplitude loading tests were carried out. The experimental results of SCC were obtained and analyzed, including P-CMOD curve, fatigue life, effective crack length, fatigue crack growth (FCG) rate, stress intensity factor (SIF). The results show that the P-CMOD curves of SCC beams

This paper attempts to establish clear rules for evaluating available experimental data that could be used for validating multiaxial fatigue strength criteria. The goal of these rules is to identify and eliminate experimental data that could lead to erroneous conclusions, that would hide otherwise visible trends or that would result in non-correct bias. Various reasons for rejecting specific data sets

A specimen-size-effect is found in the experimental fatigue crack growth behavior of single-edge-cracked fracture specimens, where the specimen length-to-width ratio was varied by about a factor of four. This effect appears from certain geometric correction factors (GCFS) used for the calcuation of the stress intensity range in fracture mechanics. It is shown that the net-section-based fracture mechanics

This paper presents a physically-based cyclic viscoplasticity model to capture the influence of welding-induced microstructural transformation on the fatigue response of the bainitic high-strength low-alloy steel, X100Q. The model incorporates the strengthening effects of dislocations, microstructural boundaries and precipitates, and the softening effects of microstructural degradation and early-life

Strain-controlled out-of-phase thermo-mechanical fatigue tests at 100-500 °C and various strain ranges were conducted on five cast iron grades, including one lamellar, three compacted and one spheroidal graphite iron. Investigations of graphite morphology and matrix characteristics was performed to associate parameters, such as geometrical features of graphite inclusions and the matrix microhardness

For metals under fatigue, microplastic strain localisation leads to the formation of discrete slip bands, which contributes to the initiation and propagation of short cracks. In this paper, a discrete slip band model is introduced to investigate the slip-controlled cyclic deformation and short crack growth in a single crystal alloy. In conjunction with crystal plasticity and normal factor-based critical

The concept of Design Fatigue Factors (DFFs) was introduced for providing desired level of safety in structural fatigue design in offshore structures, often associated with damage calculated from S-N curves. Calculation of fatigue damage from S-N curves can be affected by multiple factors, e.g. types of weld class, corrosion condition, loading conditions, stress concentration on different geometries

Additive manufacturing technology has gained significant attention in recent years. However, due to lack of sufficient understanding of their fatigue behavior under service loading conditions, design of critical load carrying parts using this technique is still at early stages. These conditions include multiaxial stress states, notches and stress concentrations, and variable amplitude load cycles.

Ships undergo cyclic loading which combined with weld defects can cause fatigue failure. Remaining fatigue life of structures containing defects can be estimated using the defect size. The defect data for ships is non-existent in literature or belong to old offshore structures. In this research, the data collected from two ships are presented. The statistical analysis of the data shows that the Hybrid

The present study reports on the results of a completed research project, which investigated the corrosion fatigue behaviour of weldments made of structural steel S355J2+N treated with the High Frequency Mechanical Impact (HFMI). Main goal has been the estimation of short corrosion on the surface layer (<1 year) on the fatigue strength of uncoated HFMI-treated specimens. Axial and 4-point bending fatigue

Mixed mode I/III fatigue fracture behaviour of bulk polymers is scarcely investigated. Thus, the aim of this work is to focus on the comparison of pure mode I and mixed mode I/III fatigue loading of polyethylene. During mixed mode I/III testing, both increases and decreases of lifetime were observed, depending on the levels of applied mode I and mode III loading. Additionally, the critical influence

The effect of material anisotropy on the fatigue crack growth (FCG) behavior in additively manufactured materials is investigated by developing an energy-based criterion. The criterion is developed based on the strain energy density concept in an anisotropic domain and considers the effects of specimen geometry by introducing the T-stress in the solution. The proposed criterion is examined by predicting