Fatigue testing campaigns are a common feature in the design and operation of advanced engineering systems in the aerospace and power generation sectors. The resulting data are typically of a high inherent technical and financial value. Presently, these data are typically transferred between departments and companies by way of ad-hoc solutions reliant on obsolete or proprietary technologies, including CSV files, MS Excel ® files, and PDFs. In these circumstances there is significant potential for data loss, inconsistency, and error. To address these shortcomings, there is a need for a systematic means of transferring data between different digital systems. With this in mind, a series of CEN Workshops on engineering materials data have taken place with a view to developing technologies for representing and exchanging engineering materials data. Most recently, a CEN Workshop on the topic of fatigue test data has delivered data formats derived from the ISO 12106 standard for axial strain-controlled fatigue testing. This paper describes the methodology for developing the data formats and demonstrates their use in the scope of the INCEFA-PLUS project on increasing safety in nuclear power plants by covering gaps in environmental fatigue assessment.

Performance of a bolted flange joint (BFJ) is characterized mainly by its ‘strength’ and ‘sealing capability’. How to keep the ‘strength’ and ‘sealing capability’ for the BFJ serving at elevated temperature is a difficult problem in engineering applications. The variations of bolt stress and gasket contact stress play an important role on the structural integrity and sealing performance of BFJ in the bolt-up, pressurization and heat-up stages. In this paper, a three-dimensional elastic-plastic finite element model has been developed to investigate the performance of joint under combined internal pressure and elevated temperature. The thermal-structural coupling method has been used to analyze the variations of axial bolt force, maximum blot stress and gasket contact stress under steady-state and transient thermal loadings. The effects of internal pressure, temperature as well as the heating rate on the variations of bolt load, bolt stress and gasket contact stress have been evaluated. The results show that the maximum bolt stress increases while average gasket contact stress decreases with increasing the temperature under steady-state thermal loading. Besides, when the transient thermal loading is considered, heating rate has a significant effect on the maximum bolt stress and gasket contact stress. This research will contribute to the design of BFJ subjected to elevated temperature.

In this study, we investigated the drawbacks of previous studies regarding the evaluation of fracture toughness from spherical indentation tests (SITs). This was achieved by an examination of the material damage mechanism during indentation tests, uniaxial tensile tests, and Mode I/II fracture tests. A new approach based on the energy release rate was proposed in this study to evaluate the fracture toughness of ductile metals. Scanning electron microscope (SEM) observations revealed that the mechanism for material damage during an indentation test was different with the material damage in uniaxial tensile tests and Mode I fracture tests, but similar to that in Mode II fracture tests. Thus, the energy release rate during SITs should be correlated with J IIC . Compared with previous studies, this new proposed method was more consistent with the actual damage mechanism and did not rely on the specific critical damage values. Experiments on SA508, SA533, 15CrMoR, and S30408 revealed that the maximum error from this energy release rate-based approach was no more than 13% when compared with their conventional counterparts (compact tension tests), and thus can meet the precision requirement of engineering applications.

In the process of compressor operation, the vibration of the pipeline occurs frequently and has a strong impact on safety. The in-field vibration measurement is carried out on the pipeline of a centrifugal compressor, and the vibration waveform and spectrum characteristics are obtained. Numerical studies are conducted to investigate the relationship between the natural frequency of the pipeline and the fluid excitation frequencies. These numerical results are verified by comparison with the field measurement values, which shows that the method can be useful for engineering applications. Some preliminary conclusions are drawn from the results of the field measurement and the numerical simulation. Pressure fluctuations not only occur in the measuring pipeline, but also spread to the pipeline in the distance. The sensitive frequencies of the pipeline vibration are determined, and the fundamental causes of the vibration revealed. Accordingly, the pipeline structure can be improved, and the method of solving the fluid excitation is discussed to avoid the damage caused by the pipeline vibration and ensure the safety of the equipment and the pipeline.

Polyethylene pipe reinforced by winding steel wires (PSP) is new type of polymer-matrix composite pipe, which is widely used in petroleum, chemical engineering, and water supply, etc. PSP is composed of a thermoplastic core pipe (HDPE), an outer cover layer (HDPE), and steel wire skeleton sandwiched in the middle. The steel wire skeleton is formed by crossly winding steel wires integrated with HDPE matrix by cohesive resin. In traditional analysis models of PSP, components of PSP were considered linear elastic, and steel wire skeleton was assumed to be orthotropic composite layer based on the classical laminated plate theory. Although achieving good results in engineering applications, traditional models neglected the material nonlinearity of steel wires and HDPE matrix, which was significant to failure analysis. In the present paper, a new finite element model was constructed using commercial software ABAQUS[1], based on the actual steel wire spiral structure of PSP. Steel wires and HDPE matrix were modeled separately, which were both represented by solid elements, and the interaction between steel wires and HDPE was characterized by tie interaction. Experimental result of short-term burst pressure of PSP was used to validate the nonlinear model. Compared with the experimental result, the calculation results of the nonlinear model agreed well. Furthermore, the effect of the nonlinear material property of components on the calculation results were investigated, and the short-term mechanical responses of PSP were determined and analyzed through the nonlinear model.

Metal matrix composites (MMCs) constitute an important class of weight-efficient structural material which empowering every field of engineering applications. Aluminium based metal matrix composites contains potential for high specific strength and advanced structural applications, as well as good elevated temperature resistance along with light weight application. However, need for improved tribological performance has led to the fabrication of newer variants of the composite. In the present work, aluminium based metal matrix composite (MMCs) developed through stir casting route by reinforcing different weight percentage of SiC micro (5% and 10%) and nano (1% and 2%) particles. In this research, 5083 aluminium alloy is used as matrix phase due its broad range of industrial applications. Wear behaviour of the developed aluminium matrix composite (AMC) was investigated under different conditions of applied load, operation time and speed. The analysis carried out at room temperature for three different loads (10N, 20N, and 30N) with varying four different operation times (30 mins, 60 mins, 90 mins, and 120 mins). The speed was kept constant at 1450 rpm during all experiments. The results of all considered composites are investigated and the composite with 2% SiC nano reinforcement is identified as a superior among all other composition for tribological applications point of view. Also the developed aluminium matrix composites have potential applications in many industries such as pressure vessels, pipe fittings, boat hulls, gears and pistons.

The high order term (HOT) solutions of crack tip field should be taken into account in engineering applications due to their potential influences on the fracture toughness as well as the crack growth rate. Towards this end, the high order asymptotic analysis of mode II crack in a power-law creeping material under the plane strain condition is presented theoretically in this paper. By comparing among the three order term solution, HRR field and finite element calculations, it can be found that the proposed three order term solution is able to characterize the full field of mode II creep crack tip accurately. The high order term solution of mode II creep crack relies on the creep exponent, which is different from that of mode I crack case. There are two independent terms among these three terms of asymptotic solution for mode II creep crack, which indicates that there exists the constraint effect for the plane strain mode II creep crack though the effect of high order term may not be as significant as the mode I crack case. Based on the theoretical analysis, a modified time-dependent failure assessment diagram (TDFAD) for mode II creep crack is proposed by considering the high order term solution.

Flow-induced acoustic resonances in piping with closed side branches or T-junctions are one of the causes of severe structural vibrations, which sometimes cause fatigue damage to piping and components in a power plant and many engineering applications. In this paper, on the basis of the results of steam flow experiments and calculations, the effects of the liquid phase on the flow-induced acoustic resonance at closed side branches in the steam flow piping of BWRs are described, and some suggestions for the steam piping design of BWRs are also given. The liquid phase in a steam flow forms droplets or liquid film, which may affect the amplitude, frequency and critical Strouhal number of the resonance. From the results of wet steam experiments and CFD calculations, we have found that in some cases the wetness of the steam flow may decrease the resonant amplitude and change the frequency owing to the interaction of the vortex generation or damping by the existence of the liquid film and droplets. Therefore, for the wet steam piping design of BWR, some suggestions for taking these effects into consideration, under actual BWR steam conditions are described.

Flow-induced acoustic resonances in piping with closed side branches or T-junctions are one of the phenomena causing severe structural vibration and fatigue damage of the piping and components in many engineering applications such as power plants. Practical piping systems of power plants often have a steam flow, and moreover, the steam state can be not only dry steam but also wet steam. From our previous experiments under low-pressure dry and wet steam flows using a single side branch, higher acoustical damping was confirmed under wet steam than that under dry steam, which is considered to be caused by the existing liquid phase. Although the static pressure in practical steam piping is often higher than that in our previous experiments, the effects of the static pressure on acoustical damping under a wet steam flow have not been clarified. Thus, we constructed a new test facility that can be used to perform continuous flow test under dry and wet steam flows with higher pressures than our previous test facility. In this paper, we give an overview of the new steam test facility and some experimental results for the acoustic resonance in a single side branch under higher-pressure dry and wet steam flows than those in our previous studies, using the new facility to investigate and evaluate the effects of the static pressure.

Stress intensity factor (SIF) solutions for subsurface flaws near the free surface in plates were numerically investigated based on the finite element analyses. The flaws with aspect ratios a /ℓ = 0, 0.1, 0.2, 0.3, 0.4 and 0.5, the normalized ratios a/d = 0, 0.1, 0.2, 0.4, 0.6 and 0.8 and d/t = 0.01 and 0.1 were taken into account, where a is the half flaw depth, ℓ is the flaw length, d is the distance from the center of the subsurface flaw to the nearest free surface and t is the wall thickness. Fourth-order polynomial stress distributions in the thickness direction were considered. Based on the results, it can be concluded that the numerical SIF solutions obtained in this study are useful in engineering applications.

Knife Gate Valves (KGV) are one of many types of valves available in the fluid control industry. Initially used for handling slurry, KGV gradually became popular in many other engineering applications. Most of these valves are characterized by a particular stuffing box shape that require a rectangular packing installation, not so conventional in valve sealing designs where packings are installed around a cylindrical stem. The actuation methods used with KGV’s are many, from purely mechanical to pneumatic and electrically actuated. The design of those actuators is most dependent of the friction generated by the packing and, therefore, knowing more accurately how packing stress influences gate drag would be of much interest. The intent of this paper is to introduce a testing device and protocol to evaluate how packing friction behaves among distinct packing materials and to establish relations between packing gland load and actuator resistive force. Moreover, values of drag force for the different packing styles are determined with corresponding gland load.

T-stress is used as an indicator of the condition of crack tip constraint. In current fracture mechanics engineering applications in the U.S. nuclear industry, T-stress generally has been ignored during the calculation of applied stress intensity factors (SIF). Consideration of this crack tip constraint component could affect the evaluation of material fracture behavior, under either plane strain or plane stress or plane strain and plane stress combination. When the T-stress shows that the condition of crack front constraint is not plane strain, incorporation of T-stress may allow reduction of unnecessary conservatisms in such calculations. Under this condition, the allowable stress intensity factor is modified by increasing it above the K Ic value, and it potentially increases the predicted allowable flaw sizes. In this paper, T-stress has been calculated using 3-D finite element analyses (FEA) with a typical semi-elliptical crack in a reactor pressure vessel (RPV) nozzle blend radius. Both thermal and internal pressure load cases are considered. To verify this finite element analysis approach, this method is applied to comparable literature models. The FEA results are consistent with closed-form solutions for T-stress calculation.

Leakage-flow-induced vibration for a relatively short gap is studied analytically to provide useful information to design structures that include a leakage flow. The relationship between the analysis of a one-dimensional system and that of an annular gap is explained first. Then, the mechanism of flutter-type instability is reproduced from previous study after correcting an error. Finally, the self-excited vibration potential of an engineering system is shown from sample calculations. It is shown that an axial flow becomes dominant in the short-gap approximation, and in this case, the analysis of a one-dimensional flow can be expanded to that of an annular flow. The result that negative damping can occur in the case of a divergent passage owing to the delay induced by fluid inertia was obtained from a previous study. It was suggested analytically that the damping ratio could become negative and its absolute value could become more than 10% in a system that is frequently encountered in a plant, if the natural frequency decreases. The value could be sufficient to generate self-excited vibration.

Flow over cavities can be a significant source of noise in many engineering applications when a coupling occurs between the flow instabilities at the cavity mouth and one of the acoustic cross-modes in the accommodating enclosure. In this paper, a passive noise control technique using a spanwise cylinder located at the cavity upstream edge is investigated experimentally for two different cavities with aspect ratios of L/D = 1.0 and 1.67, where L is the cavity length and D is the cavity depth. The effect of both the location of the cylinder and its diameter on the flow-excited acoustic resonance is investigated in air flow with Mach number up to 0.45. This passive control technique is found to be effective in suppressing the acoustic resonance excitation when compared to the base case where no cylinder is attached. It is observed that using the optimum cylinder location and diameter reduces the acoustic pressure to less than 140 Pa, compared to the base case with values exceeding 2000 Pa. Moreover, a shift in the onset of acoustic resonance to higher velocities is observed. Localized hot-wire measurements of the free shear layer at the cavity mouth during the off-resonance conditions reveal that attaching a spanwise cylinder at the cavity upstream edge reduces the spanwise correlation of the free shear layer which, in turns, reduces its susceptibility to acoustic excitation. To further understand the interaction between the cylinder’s vortex shedding and the free shear layer at the cavity mouth, a numerical simulation of the flow field using a detached eddy simulation (DES) model has been carried out. The simulation shows that the suppression occurs due to a disturbance of the cavity shear layer by the vortex shedding from the cylinder which results in altering the impingement point at the downstream edge of the cavity, and thereby weakening the feedback cycle that controls the acoustic resonance excitation.

High-amplitude acoustic pressure fluctuations associated with locked-on, resonant flow states frequently occur in engineering systems that involve internal cavities located in pipelines, such as components of gas transport systems, steam delivery pipelines and jet engines. This paper describes the evolution of fully turbulent, acoustically coupled shear layers that form across deep, axisymmetric cavities. Effects of geometric modifications of the cavity edges on the separated flow structure were investigated using digital particle image velocimetry (PIV). The internal flow was non-intrusively accessed by means of a borescope, which allowed illumination and optical recording of flow tracers inside the cavity. Instantaneous, phase- and time-averaged patterns of velocity and vorticity provided insight into the flow physics during flow tone generation and noise suppression by the geometric modifications. In particular, the first mode of the shear layer oscillations was significantly affected by shallow chamfers located at the upstream and, to a lesser degree, the downstream edges of the cavity. Specifically, the introduction of the chamfers affected the phase and the location of formation of large-scale vortical structures in the shear layer, which is associated with a maximum of the vorticity thickness across the cavity opening. In turn, these changes in the flow structure affected the amplitude of acoustic pressure pulsations.

In this paper, single-edge cracked plate (SECP) specimens are analyzed using three-dimensional finite element analysis under mode I loading conditions. The stress intensity factor K , T 11 and T 33 stresses along the crack front of the SECP specimens with the crack surface subjected to uniform, linear, parabolic or cubic stress distributions are calculated. The relative crack depth, a/W , is varied by 0.2, 0.4, 0.6 or 0.8. And the relative thickness, t/W , is chosen by 0.1, 0.2, 0.5, 1.0, 2.0 or 4.0, respectively. For engineering applications, empirical equations of normalized stress intensity factor K , T 11 and T 33 stress at the mid-plane are also obtained. By superposition, the results enable the calculations of these fracture mechanics parameters under the loading conditions of tension, bending and nonlinear stress distributions.

Measuring plastic strains is very useful method for validating finite element model of weld residual stress, which is very important for understanding welding process and facilitating other engineering applications. In this work, the distribution of plastic strains in a multi-pass dissimilar metal weld comprised of Nickel Alloy 82 and austenitic stainless steel 304L is evaluated quantitatively through micro-hardness mapping. An experiment procedure was developed to separate the contribution to hardness from the plastic strain (work hardening) that forms the chemistry variation in the dissimilar metal weld. It is found that high equivalent plastic strains are predominately accumulated in the buttering layer, the root pass, and the heat affected zone, which experience multiple welding thermal cycles. The final cap passes, experiencing only one or two welding thermal cycles, exhibit less plastic strain accumulation. Moreover, the experimental residual plastic strains are compared with those predicted using an existing weld thermo-mechanical model with two different strain hardening rules.

A response spectrum analysis (RSA) has been widely known as one of the methods used for the purpose of an earthquake-resistant design of a structure in the nuclear industry through evaluating the structural integrity during and after seismic events. Recently, as the structures, systems, and components for the design are massive, complex, and complicate, a considerable amount of computational resources and time is required for applying the RSA. Reduced methods have been considered as important technique to resolve computational resources and time problem. For a few decades, various approximate techniques have been developed to obtain the dynamic characteristic in a reduced manner. This paper adopts the model order reduction (MOR) technique known as the one of various reduction methods. The MOR for solving the large linear system in mathematics has been studied by a number of researchers. The MOR is achieved by applying a projection from a higher-order to a lower-order space using Krylov subspaces generated by the Arnoldi algorithm. It has been extended to engineering applications such as circuit analysis, structural analysis, and multi-scale analysis. However, it has not yet been applied in RSA. The aim of this study is to evaluate applicability of the MOR into RSA. Numerical examples demonstrate that the proposed method saves computational costs effectively with maintaining accuracy. Thus, it is confirmed that the proposed method is valid and applicable in predicting seismic responses.

In this paper, the phenomenon of self-sustained pressure oscillations due to the flow past a deep, circular, axisymmetric cavity is investigated. In many engineering applications, such as flows through open gate valves, there exists potential for coupling between the vortex shedding from the upstream edge of the cavity and a diametral mode of the acoustic pressure fluctuations. In the present study, the unsteady pressure was measured at several azimuthal locations at the bottom of the cavity walls, and the associated acoustic mode shapes were calculated numerically for the four representative cases of the internal cavity geometry, which involved a reference case with sharp, 90°edges as well as several modifications that involved chamfers of various length of the upstream and the downstream edges of the cavity. In addition, the flow velocity in the vicinity of the cavity opening in selected cases was measured using digital particle image velocimetry (PIV). The optical access to the highly confined internal flow was provided by implementing an endoscope attached to the camera. This global, quantitative imaging approach yielded patterns of velocity, streamlines and out-of-plane vorticity component. Instantaneous and time-averaged flow patterns provided insight into the mechanism of the flow tone generation. Among the considered cavity geometries, the configuration that corresponded to the most efficient noise suppression was identified.

Duct flows of solid-liquid slurries are frequently encountered in many engineering applications. The literature about the behaviour of such mixtures in correspondence to hydraulic singularities — such as sudden variation of duct section, perforated plates and bar screens — is rather poor, despite they are integral part of the plants. The technical difficulties faced whilst performing experimental tests made CFD almost the only possible way to study the flow field in detail. In the present work the flow of sand-water mixtures through a sudden expansion in a rectangular horizontal duct is investigated by means of a two-fluid model. Due to the lack of experimental data available, a sensitivity analysis is performed to quantify the influence of the terms of the two-fluid model which proved negligible in the horizontal pipe case, topic of previous investigations. Computations were performed for either dilute or dense mixtures, in order to study the effect of the mean solids concentration on the flow field. Moreover, the effect of channel width is investigated to assess the validity of the hypothesis of two-dimensionality of the flow.