Structural Integrity and Fatigue Failure Analysis

The model of fatigueFatigue mixed fracture, which follows from the amalgamation rule of resource safety indices, has been experimentally confirmed. It does not require finding an effective SIFStress intensity factor, but is based on the construction of survivability curves for pure modes. Survivability in a mixed process is defined as the result of combining individual fractureFracture processes. Peculiarities of steels of rolling rolls fractureFracture under conditions of cyclic deformation according to the scheme of four-point asymmetric bending are revealed. Although such a test scheme is designed to obtain the fractureFracture of the II mode, in existing studies, this has not been achieved. The crackCrack from the notch, practically, immediately went away at an angle ~45° toward the tensile zone, which indicates a mixed I+II fractureFracture. With sufficient accuracy to predict survivability, the exponent of the Paris's regionCrack of theFatigue fatigue crack growthCrack growth diagram (FCG) can be taken as nI = 4 (I mode), nII = 3 (II mode). As a parameter of schematization, it is possible to use the value of SIFStress intensity factor at an FCG rate of 10–7 m/cycle. Its value for steels of rolling rolls can be 60–70 MPa√m in mode I. For mode II, this index decreases by 2.5–3 times.

The fatigue endurance assessment of leaf springs for trailers and semi-trailers is a non-standardized procedure often protected by industrial secrecy that can significantly vary depending on the manufacturer, thus, imposing a barrier to seek for more efficient and safe structures. Hence, the main objective of the present work is to create, starting from experimental evidences, a solid technical basis for the creation of a valid accelerated fatigueFatigue test procedure able to reproduce the damage to failure inferred to a semi-trailer leaf spring allowing an accurate prediction of its durability. For that, data was collected on public paved highways and off-road tracks by strain gauges mounted on a spring, which were then extrapolated for fatigueFatigue failure through a rainflow cycle counting, yielding a damage parameter that was reproduced in special test tracks. The accelerated fatigueFatigue test created had a good correlation to real operational conditions of the spring, represented by severity factors close to 1 along the longitudinal axis of the spring.

Cast iron probably represents one of the most widely utilized constructive materials in our modern industrial world. This is due not only to the excellent mechanical and tribological properties, but also to a certain flexibility of the same. In fact, it can be produced in various types of metal alloy, which differ significantly in properties: from the poorly performing, but economical white cast iron, to the excellent resistant nodular cast iron. In this study, several preliminary results on the experimental measurement of fatigueFatigue resistance are proposed for two distinct families of cast iron, the ductile and the vermicular. While the former is well-known, with a great variety of applications, vermicular cast iron is almost unfamiliar at the moment in terms of utilization, despite different potentials. This experiment compares the results of the Rotating Bending FatigueFatigue test for cast iron specimens made under foundry process conditions as identical as possible in the way to reduce bias.

Cast iron probably represents one of the most widely utilized constructive materials in our modern industrial world. This is due not only to the excellent mechanical and tribological properties, but also to a certain flexibility of the same. In fact, it can be produced in various types of metal alloy, which differ significantly in properties: from the poorly performing, but economical white cast iron, to the excellent resistant nodular cast iron. In this study, several preliminary results on the experimental measurement of fatigueFatigue resistance are proposed for two distinct families of cast iron, the ductile and the vermicular. While the former is well known, with a great variety of applications, vermicular cast iron is almost unfamiliar at the moment in terms of utilization, despite different potentials. This experiment compares the results of the Rotating Bending FatigueFatigue test for cast iron specimens made under foundry process conditions as identical as possible in the way to reduce bias.

In the paper, the problem of long-term operated materials from nineteenth-century steel was discussed. The detailed analysis was focused on materials aspect and strength degradation based on the experimental results from rivets and metal plate from materials extracted from Sand Bridge (1861) located in Wrocław, Poland. As it is reported, the most sensitive parameters for degradation are cyclicCrack crack growthCrack growth properties. However, there is no direct link from degradations symptoms to the engineering fatigueFatigue lifetime calculation—the presented numerical analysis aimed to bridge this gap using FM-TOOL software. Obtained results suggest significant fatigueFatigue lifetime decrease caused by degradation processes. Also, crucial role plays fractureFracture resistance and thus, higher fractureFracture toughness properties expressed in cyclic stress intensity factorStress intensity factor Kfc obtained for steel in post-operated state.

In reality, damage in the reinforced concrete structure under fatigueFatigue causes poor performance under service loading. Hence, this study aims to investigate the acoustic emission characteristics of the reinforced concrete beam subjected to fatigueFatigue loading at different sensors. Laboratory experiments were performed on the 150 mm × 150 mm × 750 mm reinforced concrete beam under fatigueFatigue loading in conjunction with acoustic emission monitoring. Then, the acoustic emission parameters on four sensors such as absolute energy, amplitude and average frequency were analysed. It is found that a good correlation between acoustic emission characteristics and the normalised cycles for all sensors. Hence, the response on the acoustic emission characteristic can be used to predict fatigueFatigue damage prognosis of the reinforced concrete beam.

The project lifetime of most hydraulic units is 30–40 years. However, the actual operational conditions at HPP can significantly prolong or significantly reduce this value. If you want to correctly assess the real unit's lifetime, it is very important to take into account the whole operating range. The announced approach to calculating the total accumulated damage proposes dividing the whole operating range into specific loading blocks with a characteristic frequency and a characteristic amplitude. The fatigueFatigue damages are calculated separately for each block take into account the peculiar fatigueFatigue features of material behavior at characteristic frequencies and the total number of loading cycles. The total exhausted lifetime is the sum of the damages on each load block. The residual lifetime is the difference between allowed damage and exhausted damage. The proposed approach allows us to make reliable individual lifetime predictionsLifetime prediction for various scenarios under real operation at HPP correctly and quickly. It helps to capture the most dangerous modes and realize smart lifetime management.

In practice, fatigueFatigue properties such as stress life and strain life are often fit from a relatively small amount of data, making accurate statistical analysis a challenge. Using a strain energy based damage model to predict strain-life and stress-life curves from individual specimens (Huffman in Int J Fatigue 88:197–204, 2016 [1]), a set of curves can be created to more accurately reflect the range of strain-life values that would come from more extensive testing. This work examines how the expected variation in stress–strain properties could be used to predict the set of curves if the strain hardening behavior of the individual specimens is unknown.

This paper proposes an improved fatigue life analysis method for optimal design of EMU gear, which aims at the defectsDefects of traditional Miner fatigueFatigue cumulative damage theory. A fatigueFatigue life analysis method by modifying S–N curveS-N curve and considering material difference is presented to improve the fatigueFatigue life of EMU gear based on shape modification optimization. A corrected method for stress amplitude, average stress, and S–N curveS-N curve is proposed, which considers low stress cycle, material difference, and other factors. The fatigueFatigue life prediction of EMU gear is carried out by corrected S–N curveS-N curve and transient dynamic analysis. Moreover, the gear modification technology combined with intelligent optimization method is adopted to investigate the approach of fatigueFatigue life analysis and improvement. It is found that the fatigueFatigue life analysis and improvement method proposed in this paper has higher prediction accuracy than the traditional method in most cases. It is concluded that the fatigueFatigue life is significantly improved by applying the proposed approach to the EMU gear. The results show that it is more corresponded to engineering practice by using the improved fatigueFatigue life analysis method than the traditional method. The function of stress and modification amount established by response surface method meets the requirement of precision. The fatigueFatigue life of EMU gear based on the intelligent algorithm for seeking the optimal modification amount is significantly improved compared with that before the modification.

This paper presents fatigue life determination of automobile coil spring subjected to variable amplitudeVariable amplitude loading by considering the loading sequence effect. Fatigue failure of automobile coil spring is common occurrence that is subjected to random loading due to road conditions. Load sequence effect was found to have more significant effects in the automobile coil spring strain signals with many high amplitude events. Strain time histories of coil spring were acquired via road tests on various road conditions. To determine the effect of load sequence on fatigueFatigue life, effective strain damage model was also applied in fatigueFatigue life assessment and compared with strain-life models. Results illustrated that the lowest fatigueFatigue life of between 1.19 and 2.93 × 103 blocks was found in the industrial road signal. This owes to the high amplitude events contributing to high fatigueFatigue damage. The fatigueFatigue life of highway signals predicted using this significantly effective model is close to the predicted value using strain-life models. This is mainly because the load sequence effect was not dominant from the highway signal due to the absence of high amplitude events. Finally, the load sequence effect was found to have more significant effects in strain signals that had many high amplitude events.

The Portuguese railway sector has suffered a significant shortage of resources, generating many issues associated with the maintenance of the rolling stock affecting its operational ability. Many of these problems are caused by the fatigueFatigue phenomenon in leaf springs of freight wagons. Thus, the study of fatigueFatigue becomes an important role in the structural integrityStructural integrity of leaf springs as well as for whole rolling stock. FatigueFatigue analysis with cyclic parameters estimated from monotonic characteristics is a good option for mechanical design. Also, nominal stress obtained from classical beam theory for straight beams may be applied for trapezoidal leaf springs, even for loads close to the yielding limit of the master leaf. Despite high mean and alternating stresses for the most severe loadings, trapezoidal leaf springs have shown a fatigueFatigue-life range coincident with the high-cycle fatigueFatigue regime.

The evaluation of fatigueFatigue properties of additively manufactured metal parts with surfaces at the as-built state is matter of great interest since it has been demonstrated that surface roughness has a key influence on high-cycle fatigueFatigue properties of components. As-built surfaces contain notch-like features that work as stress concentration sites where fatigueFatigue crackCrack nucleation may occur. These typical morphologies due to Laser-Powder Bed Fusion (L-PBF) processing need to be considered in evaluating the fatigueFatigue performance; therefore, parameters related to as-built surface quality should be investigated and considered in part design. An innovative fatigueFatigue test method using miniature specimens is adopted to evaluate fatigue strength of the material; different specimen orientations are produced and tested. The fatigueFatigue results show the directional nature of the as-built surface and the surface differences introduced by the specimen orientation. In this work, as-built surfaces are investigated with two methodologies: microscopical observation of specimen cross section and optical interferometer observation of specimen surface. The irregular profiles are digitally reconstructed and evaluated via finite element analysis and the stress distributions interpreted. A correlation between stress-based parameters of surface models and fatigueFatigue strength is attempted.

In this study, fractureFracture surface topography parameters were measured to investigate the effects of multiaxial loading. In order to assess the metrological aspects of fractureFracture for notched specimens made of high-strength steels processed by both conventional and additively manufacturing (AM) techniques, an optical surface profilometer was used. Three bending moment to torsion moment ratios (B/T) were studied, i.e. 2, 1 and 2/3. The geometries were solid round bars with lateral notches made of conventional steel and hollow round bars with transversal holes for AM specimens. The investigations indicate that arithmetical mean height, Sa, decreased and fractal dimension, Df, increased with higher B/T ratios and higher fatigueFatigue lives.

Metallic Additive Manufacturing (AM) has experienced increasing levels of demand due to its flexibility in producing complex geometries, bolstered by the growing availability of topology optimization methods. However, the multiple thermal cycles associated with these processes lead to the appearance of residual stresses that can worsen the dimensional accuracy and mechanical behavior of components. Consequently, efforts have been made to propose numerical models capable of distortion and residual stress prediction of parts manufactured through Laser Powder Bed Fusion (LPBF). This article introduces the mechanisms associated with residual stress generation and reviews known Finite Element Method (FEM) formulations of the additive manufacturing problem. Simulations are proposed and conduced that aim at comparing two software packages against each other and against experimental data; results are discussed, and lastly, conclusions are achieved.

This paper offers a practical overview of the most common procedures and materials currently available in the production of end-use metal components and parts by additive manufacturing (AM). The latest achievements and news are also discussed with special attention on defining the real production capability of each technological AM option under investigation. As general conclusion, by the present technical review, it was possible to confirm the proper capabilities of AM in accelerating the development of ready-to-market metal products supporting the overall industrial investment strategy. This is especially true in the case of geometrically complex parts or small/variable production batches. Furthermore, it also emerges that a direct metal 3D printing opens to new possibilities with relevant impacts on the contemporary industry, especially if driven by with appropriate changes in the information system and technology.

FatigueFatigue behaviour of SLM 18Ni300 steel under proportional bending-torsion loading is studied. The fatigueFatigue tests are conducted under pulsating loading conditions using tubular specimens with a transversal circular hole. Three ratios of the normal stress to shear stress are considered, namely $$\sigma /\tau = {4},\sigma /\tau = {2}$$ σ / τ = 4 , σ / τ = 2 and $$\sigma /\tau$$ σ / τ  = 4/3. CrackCrack initiation sites were found for two diametrically opposite points around the hole, whose locations are governed by the loading scenario. CrackCrack angles at the early stage of growth were successfully predicted from the first principal direction at the nodes with maximum values of the first principal stress at the hole. FatigueFatigue crackCrack initiation life was estimated based on the SWT parameter, defined from uniaxial low-cycle fatigueFatigue tests performed for smooth standard specimens under fully reversed strain-controlled conditions. Overall, predicted lives are in agreement with the experiments.

The aim of the work was to find an innovative sandwich composite material that can be used as a material for loudspeaker membranes. Composite samples of a sandwich construction were made using different materials for the core: balsa wood, Poraver glass granulate, Coremat mat and polyurethane foam. Measurement of complex dynamic viscoelastic Young’s modulus was carried out using the Oberst method, allowing to select a composite sample with the best parameters in comparison with other materials: possibly high Young’s modulus and loss factor, low density and the high velocity of the longitudinal wave. The best properties are characterized by a composite whose core is made of balsa wood. The covers of all systems are made of the same material—carbon mat, known also as carbon paper. The experiment was run on selected materials for core and for outer layers.

This paper presents the experimental results of composite rebars based on GFRP and CFRP manufactured by a pultrusion system. The off-plane compression strength of rods was determined. This compression test reflects the weakest nature of the composite materials based on the interlaminar compressive strength. The proposed methodology allows us to invariantly describe the experimental transversal strength of the composite materials. As a result, the force–displacement graphs were plotted. The experimental results are compared with computational results using the Finite Element Method. In off-plane compression the matrix carries the load, all the specimens regardless of the length were cracked in the same way, in the middle of the cross-section. It is worth noting that the failure and fractureFracture mechanism plays a crucial role as a material quality indicator in the manufacturing process. The comparison showed differences between the experiment and the FEM results that may come from the imperfection in the structure.

This paper presents the numerical simulation of the GFRP rebars subjected to the bending loading. Additionally, the comparison of the mechanical properties of CFRP/GFRP laminates with different fiber volumes is given according to the widely used hypotheses available in the literature. The most suitable hypotheses are the Abolish regarding Kirchhoff's (Shear) modulus and Chamisa's regarding Young's transverse modulus. These parameters were chosen in the further Finite Element Analysis (FEA). The pure bending is used to compare the individual conceptions of the rebar designs. The pure bending is obtained by rotation of 0.262 radians (approximately 15 $$^\circ $$ ∘ ), since one end of the rod is fixed in all three directions. Profiles with a greater moment of inertia of the cross-section are preferred, which means profiles with larger overall dimensions for instance a ring-type cross-section. Additional elements enriching the cross-section, such as a coil, only slightly transfer the load.

The manufacturing process of composite pultruded rebars requires consideration of various aspects. In this work, the heat transfer at the pultrusion die was investigated. The aim was to analyze the heat transfer from the die to the GFRP composite rebar. The 3D numerical model was prepared to simulate the pulling process of the rebar through the heated die. As a result, detailed heat distribution in the composite was obtained to state, whether the complete curing process may be obtained or not. The numerical models provide the possibility to vary the pulling speed and heating temperature according to the used material composition. The presented approach can be used in the optimization process of heaters placement and their power or heating cycles.

In Europe, several bridges, as Luiz I bridge in Porto, are at the end of their service life, which is pretended to extend due to cultural value of these structures. The application of carbon reinforced polymers (CFRP) in certain regions of the structures under maintenance is a widely used methodology of strengthening. Thus, this work aims to characterize the fractureFracture mechanics properties for pure mode I of hybrid joints, which combine CFRP with steel by means of a structural adhesive. Therefore, asymmetric double cantilever beam (ADCB) type of experimental test was performed to assess pure mode I of fractureFracture. Besides, a numerical study based on a cohesive zone model was also performed, in order to design and evaluate the experimental results.

This paper aims to characterise the multiaxial strain loading signal in order to assess the durability of the coil spring in the time–frequency domain. Coil spring experiences vertical axial loading, direct shear force, and torsion during movement when subjected to cyclic loading. The experiment was set to capture random strain signal in the different angle at x-axis (0°), 45°, and y-axis (90°) from the coil spring at operating conditions. The time history of random strain signal was assessed based on kurtosis and the power spectrum density in order to analyse strain signals in time and frequency domain. The life is predicted through the strain-life models namely Coffin-Manson (CM), Smith–Watson–Topper (SWT), and Morrow model and is correlated using linear regression to obtain the relationship of the strain signal at 0°, 45°, and 90° axis. The results indicated that the strain at 45° axis shows the highest vibrational energy content followed by the strain at 90° axis and 0° axis. The fatigueFatigue life prediction for the CM, Morrow, and SWT models showed the same trend for the strain signals at 0°, 45°, and 90° axis. The correlation of strain life at 0° and 90° axis showed a good agreement with R2 value exceeding 0.9 except for 45° axis. This shows that the strain life at 45° axis is affected by the torsion. This study showed a successful establishment of the relationship between the strain signal at 0°, 45°, and 90° axis using linear regression.

For the evaluation of a structure’s fatigueFatigue life, the knowledge of detailed stress histories plays a crucial role. In industrial application, the finite element method (FEM) has become the most widely applied tool for numerical stress- and subsequent fatigueFatigue analyses. While most computational cost is spent for the evaluation of time-dependent global stress fields, the areas that are relevant for durability analyses are limited to highly stressed local regions (hot spots). For the reduction of processed data, a subsequent fatigueFatigue analysis can be carried out using so-called hot spot filters, pointing out highly stressed elements. Available methods can be summarised as posteriori methods, as they root in the calculated stress histories or modal contributions. In this paper, a novel approach is developed, based on the a priori superposition of modal fields by means of appropriate prediction of maximum modal contributions. Main influences on modal contributions are identified and suitable parameters for superposition are summarised. As modal fields are scalable, special attention is paid to mode normalisation. Combining the developed approach with material data, appropriate threshold values for hot spot detection are presented. For validation, numerical fatigueFatigue analyses are carried out on a complex FE-model from automotive industry.

This work is devoted to the problem of creation of reliabilityReliability criterion taking into account technogenic and anthropogenic factors in relation to the assessment of pipeline operation safety. There are proposed relations for the function of the structure failure probability through the failure probability of its similar structural elements. The structural element durability is found taking into account the results of the analysis of the probability of metal failure at a certain level of accumulated defectsDefects. Assuming that the failure probability should not exceed its acceptable value (the criterion of structural reliabilityReliability), the relation for finding the structure life is written. The classification of damaging factors at destruction of structural elements of product pipelines has been carried out. The ratios for social, industrial and environmental risks used in the calculation practice are given. The acceptable values of risks are considered. A safe operation criterion in the form of an inequality is proposed, in which the structural risk does not exceed an acceptable value, multiplied by a coefficient determined by the calculated and acceptable values of industrial, social and environmental risks. The criterion is a theoretical generalization of the known relationships used in design practice of investment projects on the construction and operation of various structures of product pipelines.

The results of rolling friction experimental research of two cylindrical rollers on the special testing stand, which imitates the operation of a rotating kiln support unit, are presented in this article. The rolling friction moment is determined using the special plate clutch on the driving roll shaft. The rolling peripheral velocity, radial load and the rollers contact surfaces condition are the variable parameters. The actual values of the rolling friction coefficient under different rolling conditions are calculated. The regularities of rolling friction coefficient changes from the rolling speed, oil viscosity and contact pressure from the radial load, which is corresponding to the real values in the basic support units of industrial rotary kilns, are established. The wear intensity effect on the rolling friction moment is determined. The range of the rolling friction coefficient, which should be taken into account in the calculations of power losses in support units of large-dimension rotational assemblies, are recommended.

This research is dedicated to the problem of automatic monitoring of the operational loading of heavy vehicles for minerals transportation in harsh conditions of underground mines. The torsional vibrations excited in the powertrains by the driver’s control actions (running, loading, reverse) are investigated on the multi-body nonlinear dynamical model, which accounts diesel engine torque characteristics, changes in transmission structure due to gears switching, lock-up activation in the hydraulic torque converter and angular clearances in the Cardan shafts couplings. The slowly sampled real signals of the on-board monitoring system are combined with the fast modelled transient responses in the range of torsional natural modes. The obtained results of simulations allow observing and optimisation of the most severe working modes to reduce amplitudes of torsional vibrations, which cause the abrupt failures in the vehicles. Besides, the database is under development for fatigueFatigue cycles accumulation and remained useful life prediction of powertrains elements for diagnostics procedures and maintenance planning.

This paper represents the study of the briquetting presses operation under conditions of rolls gradual wear and diversity of bulk raw materials with varying fractions and physical–mechanical properties. The model of the contact wear is developed to predict product quality (briquettes density) and energy-power parameters of the compaction process. The experimentally established wear patterns of the replaceable tires have a good correlation with predicted values. Based on the model simulations, the optimized modes of briquetting process are recommended at different stages of rolls wear, which are tested in a production plant. This approach provided tires service up to 11 mm of wear instead of 5–6 mm with satisfying the required quality of briquettes made of silicomanganese with an organic binder and ensured the limitations on available mechanical drive loading and electric motor power. The results of the research are the basis for the development of monitoring, controlling systems, and maintenance optimization, taking into account the gradual wear of the tires.

This paper presents the development of a multiple linear regression based on stress ratio and applied load approach, assessed via thermodynamic entropy generation. Entropy generation as an early detection method that enables researchers to discover temperature evolution caused by dissipated plastic energy if the material experienced fatigue load. This relationship was developed through a complete entropy generation prediction using statistical approachEnergy approach, whereby a constant amplitude loading was applied to evaluate the fatigueFatigue life. By conducting compact tension tests, different stress ratios of 0.1, 0.4, and 0.7 were applied to the specimen. During the tests, temperature change was also observed. The highest entropy generation was 2.922 MJ m−3 K−1 when 2600 N load with a stress ratio of 0.7 was applied to the specimen. The assumptions of the models were considered through graphical residual analysis. As a result, the predicted regression model based on the applied load and stress ratio corresponded with the results of the experiment, deviating at only 4.6% from the actual experiment.

Thin plates are widely used in structural engineering as components of decks and bottom of ships, offshore structures, aircrafts, and bridges. If these plates are subject to compressive loads, the buckling phenomenon can occur. The presence of cutouts on plates causes a redistribution of the membrane stresses, altering its buckling behavior. In this context, simply supported square steel plates with a centered elliptical hole and subjected to biaxial compression were geometrically evaluated. To do so, the Constructal Design (CD) was applied to propose the geometric configurations (search space); the Finite Element Method (FEM) was used to obtain the ultimate buckling stress of these plates; and the Exhaustive Search (ES) technique allowed to define the optimized plate geometries. The perforation assumed five different sizes, and for each size several variations of its elliptical shape were investigated. As performance parameter, the maximization of the ultimate buckling stress was considered. From the results, it was observed that the optimized geometric configurations are in agreement with the Principle of Optimal Distribution of Imperfections, showing the applicability of CD in evaluation of structural integrityStructural integrity of these plates.

In the present work, it is developed a computational methodology for prediction of mechanical behavior of brackets used for support of fairleads of mooring systems subjected to the maximum environmental load. With the developed methodology, different geometric configurations are studied for brackets using thinner plates than that commonly employed in existent brackets of P-66 Petrobras oil production platform. Theoretical recommendations about geometrical configurations that reduce the von Mises maximum stress in brackets’ plates are obtained using Constructal Design. For the solution of distribution of stresses along with the solid domain of the brackets, it is used a code based on the Finite Element Method, more precisely the ANSYS Mechanical APDL. The brackets studied here are composed of AH36 steel plates. Three different configurations for the base of superior brackets are compared: rectangular, rectangular/triangular, and rectangular/trapezoidal. Results indicated the importance of geometrical investigation in this kind of problem. The rectangular bracket led to mechanical performance, nearly 35%, and 38% superior to that achieved with rectangular/trapezoidal and rectangular/triangular bases, respectively.

The present study is aimed at the identification of equivalent viscoelastic models for layered thin-walled structures, obtained from vibration measurement only. Accurate modelingModelling of modal properties is fundamental for describing metal fatigueFatigue, caused by forced vibration on structural components. A new approach is proposed, based on a definition of an equivalent modal damping ratio applied to the circle-fit technique, to overcome the difficulties related to the identification of modal parameters when adopting non-conventional viscoelastic models. When the structural internal dissipative effects are dominant, this procedure identifies the parameters of an equivalent Young’s modulus in the frequency domain. The proposed procedure is applied to the analysis of plates made by quiet aluminum, adopting the linear fractional Kelvin-Voigt viscoelastic model and assessing the accuracy of the identified parameters by comparison of numerically simulated with experimentally measured frequency response functions.

Machine learning is an important tool used in many science branches. In this paper, neural network is created to predict reaction forces in the plate under tension. The automatized Python script is used to generate model, solve model, obtain results and process data in SIMULIA Abaqus environment. The script was then used with over 15,000 combinations of 6 independent input parameters. Reaction forces in three directions were obtained in this process. Created in this way, dataset is normalized and used as the training dataset for a neural network. Errors obtained for simple structure in this approach are small and comparable to the error of the finite element method itself. This approach demands preparing a large dataset, but it can be worth it if the application lets analysis in real time, i.e., construction monitoring or medicine.

Contraction weld stress creates distortions that are never desired especially in a vehicle such as a racing motorcycle. Every dimension deviance may have an impact on drivers’ safety, assembly accuracy, or performance. The following article presents a motorcycle frame and swingarm (constructed by students of Wroclaw University of Science and Technology) after they were welded. Those items were 3D scanned and compared with their 3D models. Figures present the most significant distortion, which is later discussed. Additionally, some welds were inspected and analyzed using an X-ray scanner. The conclusion reveals that it is only possible to minimalize deviances by actions such as positional welds and properly constructed welding stance.

The paper defines areas where a working machine or device may be a source of external forces on the control elements of hydraulic valves. The influence of external mechanical vibrations carries a number of unfavorable and undesirable effects on the operation of hydraulic valves. During the experimental tests, the valve was affected by external mechanical vibrations of known amplitude and frequency. The test stand of the hydraulic measuring system is described. Exemplary amplitude-frequency characteristics for selected parameters are presented. The work describes the application of the sequential graph method to analyze the impact of vibrations on a micro-hydraulic valve. The procedures for determining the sequence of the importance of parameters in relation to the graphs used were defined. The analysis of iterative systems, i.e., those that contain a certain set of interval chains with the same basic cell (interval) but with a different rank of importance, is an important tool for the diagnostic analysis of systems built on functions. This will eventually allow multi-valued decision trees to be used for analysis in the intervals concerned.