Chemical pressure storage tanks are containers designed to store fluids at high pressures, i.e., their internal pressure is higher than the atmospheric pressure. They can come in various shapes and ...sizes, and may be fabricated from a variety of materials. As aggressive chemical agents stored under elevated pressures can cause significant damage to both people and the environment, it is essential to develop systems for the early damage detection and the monitoring of structural integrity of such vessels. The development of early damage detection and condition monitoring systems could also help to reduce the maintenance costs associated with periodic inspections of the structure and unforeseen operational breaks due to unmonitored damage development. It could also reduce the related environmental burden. In this paper, we consider a hybrid material composed of glass-fiber-reinforced polymers (GFRPs) and a polyethylene (PE) layer that is suitable for pressurized chemical storage tank manufacturing. GFRPs are used for the outer layer of the tank structure and provides the dominant part of the construction stiffness, while the PE layer is used for protection against the stored chemical medium. The considered damage scenarios include simulated cracks and an erosion of the inner PE layer, as these can be early signs of structural damage leading to the leakage of hazardous liquids, which could compromise safety and, possibly, harm the environment. For damage detection, PZT sensors were selected due to their widely recognized applicability for the purpose of structural health monitoring. For sensor installation, it was assumed that only the outer GFRP layer was available as otherwise sensors could be affected by the stored chemical agent. The main focus of this paper is to verify whether elastic waves excited by PZT sensors, which are installed on the outer GFRP layer, can penetrate the GFRP and PE interface and can be used to detect damage occurring in the inner PE layer. The efficiency of different signal characteristics used for structure evaluation is compared for various frequencies and durations of the excitation signal as well as feasibility of PZT sensor application for passive acquisition of acoustic emission signals is verified.
In recent years, with the people’s awareness of the changes in the fitness movement, aerobics has become one of the most popular sports. Although it is only a moderate intensity of sports items, but ...there are still likely to be injured in aerobics, therefore, the study of different materials for the special purpose of the shock absorption properties of aerobics has a very important significance. Selected rubber, EVA, TPU these three different materials made of Aerobics special shoes for shock absorption loss prevention test, the structural design of three kinds of shoes. Through the analysis of parameters in the process of the experiment can be seen, TPU materials damping loss prevention effect is the most ideal rubber anti vibration effect of the worst.
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•Development of a material damage model for ECC under fatigue loading.•Calibration of material damage model parameters for ECC under fatigue loading.•Development of a simplified FE ...procedure for ECC beams under fatigue loading.•Validation of the proposed simplified FE analysis procedure with test results.
This study proposes a new finite element (FE) analysis procedure for simulation of flexural fatigue behaviours of hybrid fibre reinforced engineered cementitious composite (hybrid ECC) beams. The proposed method simplifies the analysis of hybrid ECC beams under fatigue loading, which could have fatigue life up to millions of cycles, into a small number of static FE analyses corresponding to a set of designated load cycles with equivalent fatigue damages. An ECC material damage model is first developed to describe the degrading of material properties caused by fatigue loading. This material damage model defines the relationships of two critical damage properties of ECC, namely the degraded stiffness and the accumulated plastic strain with the number of load cycles applied. By using the developed material damage model, a simplified analysis procedure is then proposed for the fatigue analysis of hybrid ECC beams under bending. The accuracy and reliability of the proposed material damage model and analysis procedure are validated by comparing experimental results obtained from bending tests of three types of hybrid ECC beams under three different stress ranges with the modelling predictions. It is found that the proposed material damage model and analysis procedure provided good predictions of the fatigue responses of the hybrid ECC beams in terms of material damages, deformation and fatigue life.
•In this study, we analyzed for the first time the causes of mending material breakage from a hemodynamic point of view.•Fluid-solid coupling models were developed based on real-life cases of mending ...material breakage after sigmoid sinus wall reconstruction surgery.•High stress and displacement may be the key cause of mending material breakage.•Blood flow impingement is an important factor in the breakage of mending materials.
Sigmoid Sinus (SS) Wall Reconstruction (SSWR) is the mainstream treatment for pulsatile tinnitus (PT), but it has a high risk of recurrence. The damage of mending material is the key cause of recurrence, and its hemodynamic mechanism is still unclear. The purpose of this study was to investigate the hemodynamic causes of mending material breakage.
In this study, six patient-specific geometric models were reconstructed based on the data of the computed tomography angiography (CTA). The transient fluid-structure coupling method was performed to clarify the hemodynamic state of sigmoid sinus and the biomechanical state of the mending material. The distribution of stress and displacement and the flow pattern were calculated to evaluate the hemodynamic and biomechanics difference at the mending material area.
The area of blood flow impact in some patients (2/6) was consistent with the damaged location of the mending material. The average stress (6/6) and average displacement (6/6) of damaged mending material were higher than those of complete mending material. All (6/6) patients showed that the high-stress and high-displacement proportion of the DMM region was higher than that of the CMM region. Moreover, the average stress fluctuation (6/6) and average displacement (6/6) fluctuation degree of damaged mending material is larger than that of complete mending material.
The impact of blood and the uneven stress and displacement fluctuation of the mending material may be the causes of mending material damage. High stress and high displacement might be the key causes of the mending material damage.
•Safe load-carrying mechanism of a Double Shear Bolted Bracket (DSBB) connection.•Parametric study on the 6-bolt and 8-bolt configurations.•Less bolt diameter and pretension force, fast erection, ...cost-efficient construction.•Sufficient rotational stiffness for strong joints and long beams.•Less or equal damage risk of DSBB segments than code-prequalified Kaiser connection.
Double shear bolted bracket connections (DSBBs) have been introduced in 2020 as reliable, cost-efficient, fully restrained connections. The double shear performance of bolts allows efficient reduction of bolt material usage in these types of connections. This advantage also shortens the time of bolt installation in steel moment frames. The design methodology and global hysteresis response of the DSBB connections were already presented in the scientific literature. However, the present study discusses the material damage by investigating the precise stress state of DSBB segments, connection stiffness evaluation, and energy dissipation distribution around the connection. Indeed, efficiency of the design guidelines and DSBB geometrical shape is thoroughly evaluated with the help of parametric studies of this discourse. Thus, the damage investigation of the main and parametric DSBB connections is developed by monitoring the prevalent damage indices. These damage indicators are plastic equivalent strain, rupture index, longitudinal plastic strain in bolts, undesirable out-of-plane deformations, buckling deformations, and prying action. In order to validate the results of this study, Kaiser Bolted Bracket (KBB) connection as a code-prequalified connection is selected in these comparative studies. In addition to the acceptable structural performance, DSBBs have more efficient and safer performance than or at least equivalent to the code-prequalified KBB connections.
Composite Material Damage Processes Bolf, Davor; Zamarin, Albert; Basan, Robert
Pomorski zbornik,
06/2020, Letnik:
Special edition, Številka:
3
Journal Article
Recenzirano
Odprti dostop
Composite materials are in use in the shipbuilding industry for a long period of time. Composites appear in vast number of fibre – matrix combinations and can be produced with several different ...production processes. Due to the specific nature of the composite material structure, the selection of the production process and the limitations in the quality control procedures, composite materials will always be subject to defects and imperfections which may, under certain circumstances, lead to the appearance and propagation of cracks. The size and the shape of the crack, the load type and the stress field in the material surrounding the crack will be crucial for crack growth and crack propagation. This paper reviews the composite material damage processes especially relevant for shipbuilding. The basic principles of composite material fracture mechanics are briefly explained, and finally, mechanisms responsible for the development of damage and fracture of composite materials are presented. This paper has emerged from the need to summarize information about composite material fracture and failure mechanisms and modes relevant for the shipbuilding industry.
The aim of this work was to study the mechanical, electrical and chemical effects of high-voltage electrical discharges (HVED) and their role in polyphenol extraction from vine shoots. Cutting and ...grinding pretreatments were conducted prior to HVED treatment. Thus, different initial specific surface areas (a0=6, 8.5, 11, 84 and 1885.19cm−1) of vine shoots were tested. When the initial specific surface areas were low (a0=6, 8.5, 11cm−1), the HVED induced damage degrees (D) were the highest, leading to a better enhancement of polyphenol extraction. However, no product fragmentation was found for the lowest particle size (a0=1885.19cm−1) before and after the HVED treatment, and despite it, an amelioration of polyphenol content in extract of 20mg/L was observed. The electrical arc generated H2O2 but did not lead to polyphenol degradation.
This study gives significant information about the action mechanisms of high voltage electrical discharge treatment presenting relevant data for the design of the process. It shows the effectiveness of electrical discharges for the intensification of the extraction of bioactive molecules (polyphenols) from a specific byproduct (vine shoots). The paper also presents an energy-saving extraction process, relevant for industrial application, since no organic solvents were used. Process duration and temperature were also reduced.
•High voltage electrical discharges (HVED) cause vine shoot fragmentation.•HVED has an electrical effect that enhances polyphenol extraction.•HVED has a chemical effect by hydrogen peroxide (H2O2) formation.•Vine shoot polyphenols are not degraded by H2O2 during the HVED treatment.•Vine shoot polyphenols scavenge free radicals and inhibit H2O2 production.
Entropy generation from a mechanical and thermal perspective are quantitatively compared via molecular dynamic (MD) simulations and mechanical and thermal experiments. The entropy generation values ...regarding mechanical tensile loading-which causes invisible damage-of the Polyamide 6 (PA6) material are discussed in this study. The entropy values measured mechanically and thermally in the MD simulation were similar. To verify this consistency, mechanical and thermal experiments for measuring entropy generation were conducted. The experimentally obtained mechanical entropy was slightly less than that calculated by MD simulation. The thermal capacity is estimated based on the specific heat capacity measured by differential scanning calorimetry (DSC), applying the assumed extrapolation methods. The estimated entropy generation was higher than the aforementioned values. There is a possibility that the entropy-estimating method used in this study was inappropriate, resulting in overestimations. In any case, it is verified that entropy increases with mechanical loading and material invisible damage can be qualitatively detected via thermal property measurements.
•The refinement model of damage evolution realizes the cross-scale conversion of damage information about structural components of RC shear walls from the local material scale to the component scale.
...The influence on the seismic behavior of RC shear walls by axial loads is evaluated and the observed damage in the earthquake damage investigation of RC shear walls is reproduced in this paper. Six RC shear walls with aspect ratio of 2 were analyzed by the method of nonlinear finite element under different axial load ratios, and the suggested modeling techniques and the accuracy of the numerical method were verified. The seismic performance of shear walls including load–displacement responses, ductility performance, stiffness degradation and energy dissipation capacity were discussed. The analysis results indicate that axial load has a significant effect on the seismic performance of RC shear walls. On the basis of this, the qualitative and quantitative relationships between the development of material damage and the deterioration of component performance were analyzed. It realizes the cross-scale conversion of damage information about structural components of RC shear wall from the local material scale to the component scale. Then the cross-scale refinement model of damage evolution of RC shear walls in the whole process was established, simplified and verified. The results show that, the refinement model can explain the development and distribution of damage evolution of RC shear walls in the whole process quickly and easily. The research results can provide a reference for the refinement of seismic design, damage assessment and reinforcement of RC shear walls.
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