Higher Vibration Modes Research Articles

Effect of the Pyrolysis Environment in a Complex Compound in the Synthesis of In0.6Ga0.4N Powders and their Characterization

In this work, the comparison between nitrogen and air synthesis environments in obtaining In0.6Ga0.4N powders is presented, and the effect of how the air environment can reduce the pyrolysis temperature of In0.6Ga0.4N powders to 271 °C using the thermal gravimetric analysis, and derivative thermogravimetry methods. X‐ray diffraction patterns demonstrate the presence of a cubic phase in nanocrystallites, in addition to less presence of the hexagonal phase. In contrast, scanning electron microscopy micrographs show a surface morphology of irregular agglomerates with a porous appearance and the presence of nonuniform plates. Energy‐dispersive spectroscopy and X‐ray photoelectron spectroscopy spectra demonstrate the presence of elemental contributions of gallium, indium, and nitrogen. At the same time, transmission electron microscopy shows the cubic structure and an interplanar distance of 2.7 Å for the (200) plane. Raman scattering shows the presence of E2(high) vibration mode for the hexagonal phase with a value of 560 cm−1. Finally, the photoluminescence spectrum shows an energy emission at 1.39 eV (886 nm), which is associated with the emission of the In0.6Ga0.4N powders.

DFT insight into the structural, vibrational, and electronic properties of thin [110] Ge nanowires as anodic material for Li batteries

Germanium nanowires could be used to improve as anodic materials since their charge rate is better than that of the current graphite electrodes. In this work, we present a Density Functional Theory study of the effect of interstitial Li atoms on the vibrational, electronic, and mechanical properties of ultrathin hydrogen-passivated Ge nanowires (HGeNWs) with diamond structure, grown along the [110] crystallographic direction, and with a diameter of ∼14.4 Å. The interstitial Li atoms were placed at the tetrahedral positions (Td) reported as the more favorable ones. The phonon band structure of the HGeNWs reveals the existence of high frequency vibrations due to the hydrogen atoms at the nanowire surface. The effect of one interstitial Li atom in the nanowire leads to the apparition of three flat phonon bands almost independent of the collective vibrational states of the nanowire, reflecting a weak interaction between the Li atom and the neighboring ones; and a shift of the high vibrational modes to lower frequencies that results in more dispersive states. The electronic band structure confirms a transition from semiconducting to metallic behavior by adding a single Li interstitial atom per unit cell. The formation energies indicate that the nanowires with interstitial Li atoms are stable, and the average binding energy per Li atom slightly increases as a function of the concentration of Li atoms. The insertion of Li atoms in the nanowire leads to a volumetric expansion, without fracture or broken bonds. Even more, the redistribution of the electronic charge due to the Li atoms give the Ge-Ge bonds more axial elasticity and the values of the modulus of Young are almost constant for all studied concentrations of Li atoms. These theoretical results indicate an improvement of mechanical and electronic properties of Ge nanowires through the addition of interstitial Li atoms that could be important for their use as anodes in rechargeable Li batteries.

(Invited) Photophysical Properties and Photodynamics in CdSe Quantum Dots as Photocatalysts and Photosensitizers

Interactions between dye molecules and the semiconductor quantum dots (QDs) has a strong effect on both solar-to-electrical and solar-to-chemical energy conversion processes. In both types of applications, the charge transfer from the photoexcited QD to the molecule play a crucial role. Applying DFT-based non-adiabatic molecular dynamics, we have revealed ultrafast hole transfer (~10 fs) from the CdSe QD to the Ru(II) dye, following by a slow component (~100 fs) associated with the redistribution of population throughout QD states. The ultrafast interfacial QD-to-dye hole transfer is rationalized by strong non-adiabatic couplings between the QD surface states and the high frequency vibrational modes of isocyanide ligands in the dye. We also have studied the effect of the complex heterostructures of Janus QDs, where a half of the QD is made from CdSe and another half is from PbSe forming an interface along a specific crystalline direction. Our calculations show that the Pb-enriched (111) crystalline direction of the interface enhances optical response of the QDs. The hole relaxation is much slower than the electron relaxation, followed by the hole transfer to the dye. The hole transfer is sensitive to the polarity of the environment, rather than the ways of dye’s attachment to the surface. We also found that in nonstoichiometric QDs, a loss of a passivating ligand affects the electronic structure in the same way as injection of an electron in Cd-rich QDs or hole injection in Se-rich QDs. Moreover, electron injection to the Se-rich QDs results in highly optically active redshifted transitions associated with the introduced charge. Overall, our calculations provide atomistic insights into QD-to-molecule charge transfer, giving researchers an additional handle for enhancing QD photophysical properties by means of the QD stoichiometry, interface structure, and QD-molecule engineering.

Model updating of a shear‐wall tall building using various vibration monitoring data: Accuracy and robustness

SummaryAcceleration measurements are often used for model updating of civil engineering structures, especially in the case of seismic monitoring. It is yet unclear if accelerations alone would generate an accurate and robust finite‐element (FE) model. This study examines this notion and analyzes the possibility of using other vibration monitoring data for model updating of shear‐wall tall buildings. This study compares the accuracy and robustness of the FE models being optimized via accelerations, roof displacement, wall rotations, interstory drift ratios, and the linear combination of these measurements. A numerical case study is analyzed using Timoshenko beams for modeling the lateral vibration of a benchmark 42‐story building under seismic excitations. Results show that the acceleration response of the examined building is mostly governed by its higher vibration modes. Depending on the characteristics of ground motions, using accelerations alone may generate an FE model biased towards higher‐order modes without effectively capturing the lower‐order modes. For instance, the first modal frequency of the updated FE model could be 12.0% lower than the true value, and the reconstructed displacement and rotation responses are noticeably inaccurate. Employing multi‐source monitoring data for model updating, for example, the combinations of roof displacement and acceleration measurements, could reduce the normalized root‐mean‐square errors in displacements by more than 70%. This study also quantifies the robustness of the FE model under various measurement noise levels and 50 pairs of earthquake records. Finally, the effects of multi‐source data on FE model updating are validated via experiments on a 7‐story shear wall building. Analysis reveals that a more accurate and robust FE model can be determined via a combination of accelerations and top displacement than via acceleration alone.

Damping enhancement of nodal modes for stay cables using a single-sided pounding tuned mass damper (SS-PTMD)

Extra long stay cables, owned characteristics of light weight and low damping, may produce large-amplitude vibrations in modes with relatively high frequencies under a moderate wind speed. Installing a transverse fluid viscous damper near the cable anchorage to add maximum damping to the first few cable modes is a traditional method to improve the cable modal damping ratio. However, the installation location of the damper may be coincide with the nodal point of some high vibration modes, and diminishing the damping effect to a large extent. To tackle this nodal mode issue, a single-sided pounding tuned mass damper (SS-PTMD), which exhibits superior control performance over a conventional tuned mass damper (TMD), is adopted to enhance the damping ratio of nodal modes. The coupled equations of motion of a cable equipped with a SS-PTMD are established, and impact force between damper mass and the cable are considered by a impact force model. Free pounding tests are performed to study the pounding behavior with different viscoelastic (VE) material layers and various types of pounding strikers. Numerical simulations are carried out to investigate the damping enhancement and vibration mitigation effect of the SS-PTMD on the cable under various loading cases, including harmonic and simulated turbulent wind excitations. Field performance validations of the SS-PTMD is performed on a cable numbered A10 of the Dongting Lake Bridge. The results from free pounding tests show that the selection of the VE material layers and strikers can greatly affect the pounding behavior of the SS-PTMD. The Numerical simulation of the coupled cable-SS-PTMD system reveals that the SS-PTMD can effectively enhance the damping ratio of the target mode by a SS-PTMD with only 1.08% mass ratio. The numerical results show that SS-PTMD is effective in mitigating the high-oder nodal mode vibration of the cable. Field tests show that after the installation of SS-PTMD, the 2nd-mode modal damping ratio of the cable increases from 0.15% to 1.8%.

Low-frequency ultrasound for pulmonary hypertension therapy

BackgroundCurrently, there are no reliable clinical tools that allow non-invasive therapeutic support for patients with pulmonary arterial hypertension. This study aims to propose a low-frequency ultrasound device for pulmonary hypertension therapy and to demonstrate its potential.MethodsA novel low-frequency ultrasound transducer has been developed. Due to its structural properties, it is excited by higher vibrational modes, which generate a signal capable of deeply penetrating biological tissues. A methodology for the artificial induction of pulmonary hypertension in sheep and for the assessment of lung physiological parameters such as blood oxygen concentration, pulse rate, and pulmonary blood pressure has been proposed.ResultsThe results showed that exposure of the lungs to low-frequency ultrasound changed physiological parameters such as blood oxygen concentration, pulse rate and blood pressure. These parameters are most closely related to indicators of pulmonary hypertension (PH). The ultrasound exposure increased blood oxygen concentration over a 7-min period, while pulse rate and pulmonary blood pressure decreased over the same period. In anaesthetised sheep exposed to low-frequency ultrasound, a 10% increase in SpO2, a 10% decrease in pulse rate and an approximate 13% decrease in blood pressure were observed within 7 min.ConclusionsThe research findings demonstrate the therapeutic efficiency of low-frequency ultrasound on hypertensive lungs, while also revealing insights into the physiological aspects of gas exchange within the pulmonary system.

Evaluation of Damage Severity and Strength of Structural Member Using Macro‐Molecular PZT Sensor

AbstractThe structural health of various engineering systems has been easily monitored using macromolecular piezoelectric ceramic lead zirconate titanate (PZT) based electromechanical impedance (EMI) technique. It is in need to study the evaluation of various levels of damage and the present strength of structural systems to enhance the life of structures. Once damages occur, due to continuing usage they usually propagate in certain directions. Moreover, the increase in the severity of damages may lead to failure of the structural components or even the whole structure. Interaction between structure and PZT, which is found effective in EMI technique, is to identify effective damage detection. The macro‐molecular PZT's self‐actuating and sensing properties are utilized by the electromechanical impedance (EMI) method. The higher modes of vibration are locally activated by the local application of an AC source on the PZT transducers attached to the host structure. In this paper, the EMI technique using surface‐bonded PZT transducers is employed to obtain the structural health signature. The experiment is carried out on a real‐size concrete frame structure subjected to artificial damage to identify and locate the damages using frequency variations, and the severity is checked using extracted equivalent parameters; the damage index. This method also can identify hair‐like cracks at an early stage, which explains how it can shield the building from serious failures.

Polymeric Macro‐Molecular Piezoelectric Sensors for Evaluation of Structural Damage

AbstractFinding damages and their prevalence in structures is a very challenging problem. In order to identify potential structural damage, non‐destructive methods are not very helpful. One of the most popular piezoelectric ceramic materials used worldwide is macromolecular lead zirconate titanate (PZT), also known as Pb[Zr(x)Ti(1‐x)]O3. PZT transducers are proving to be a successful alternative for assessing the structure's health. The Macro‐molecular PZT's self‐actuating and sensing properties are utilized by the electromechanical impedance (EMI) method. In this capacity, the macro‐molecular PZT patches serve as co‐located actuators and sensors and make use of ultrasonic vibrations to produce a distinctive admittance “signature” of the structure. PZT patches perform exceptionally well in terms of damage sensitivity. The higher modes of vibration are locally activated by the local application of an AC source on the PZT transducers attached to the host structure. The alteration of the admittance response is a sign of injury to the transducer's vicinity. In the current study, the damage percentage and its location in a 150 × 150 × 150 mm concrete cube are being examined. Regression analysis is also used to determine the concrete cube's strength. This method also can identify hair‐like cracks at an early stage, which explains how it can shield the building from serious failures.

Effect of Bending Rigidity and Nonlinear Strains on Free Vibration of Hemi-Ellipsoidal Shells

Abstract This paper focuses on free vibration of hemi-ellipsoidal shells with the consideration of the bending rigidity and nonlinear terms in strain energy. The appropriate form of the energy functional is formulated based on the principle of virtual work and the fundamental form of surfaces. Natural frequencies and their corresponding mode shapes are determined using the modified direct iteration method. The obtained results, which show a close agreement with previous research, are compared with those obtained based on the membrane theory. The effect of the support condition, thickness, size ratio, and volume constraint condition on frequency parameters and mode shapes is demonstrated. With the bending rigidity, shell thickness has a significant impact on the frequency, especially in higher vibration modes and in shells with a considerable thickness but the frequency parameter converges to that determined by using the membrane theory while the reference radius-to-thickness ratio is increasing. In addition, accounting for the bending rigidity solves the issue of determining natural frequencies and mode shapes of the shells using the membrane theory without the volume constraint condition. The obtained results also indicate that the free vibration analysis with bending is essential for the hemi-ellipsoidal shell with a base radius-to-thickness ratio of less than 100, which gives over 2.84% difference compared with that of the shell derived by membrane theory, and this allows engineers to perform the analysis in more applications.

Vibration-based hidden damage imaging using stereo cameras with digital image correlation

This paper explores a full-field non-contact optical sensing technique using a stereo camera for imaging hidden damage based on vibration-based damage detection methodology in structural health monitoring. The technique utilizes a pair of digital cameras to capture dynamic operational deflection shapes (ODSs) over the region of interest (ROI) of a structure’s surface via digital image correlation (DIC) when subjected to vibrational excitation. This research overcomes bottlenecks in using high vibration modes for imaging the hidden damage area by (1) applying DIC to operational modal analysis with simple pick-peaking techniques to gather natural frequencies and operational mode shapes in plate structures, while (2) using wavelet analysis to reveal the image of the damage region as a means for baseline-free global damage quantification. In the feasibility study, four cases with two aluminum plates with large damage regions were investigated with a vibration shaker generating a frequency sweep up to 1 kHz. The stereo camera imaged the speckled surface of the plate with white light. Once the dynamic ODSs in the ROI were observed using DIC, the natural frequencies and associated operational mode shapes were extracted using a peak-picking technique in the frequency spectrum. Natural frequencies and operational mode shapes from finite element analysis correlated well with the experimental observations from three-dimensional DIC for all 12 vibration modes respectively. A wavelet transform mode shape curvature (WT-MSC) technique to obtain the modal shape curvature via a two-dimensional continuous wavelet transform with a Mexican Hat analyzing wavelet was then implemented on each of the first 12 vibration mode shapes. A damage image condition that incorporates all weighted wavelet coefficients is proposed to image the damage region. The hidden damage was visualized clearly with WT-MSC, as the technique is much less sensitive to noise than the use of MSC alone, and the use of high vibration modes exhibiting larger mode shape curvatures provided a greater sensitivity for imaging the damage region. Hidden damage regions were successfully visualized in all four cases.

An accurate and efficient 4-noded quadrilateral plate element for free vibration analysis of laminated composite plates using a refined third-order shear deformation plate theory

An accurate, efficient and reliable four-noded quadrilateral plate element is developed for the free vibration analysis of laminated composite plates. The element formulation is based on a refined third-order shear deformation plate theory (TSDT) and the quasi-conforming element technique. The equations of motion and the variational consistent mass matrix are derived through Hamilton’s principle. The resulting composite plate element is free from shear locking. Furthermore, both its element stiffness and mass matrices are computed explicitly. The convergence and accuracy of the present element are evaluated by the standard static and dynamic examples of isotropic plates. The accuracy of the computed natural frequencies of laminated composite plates is verified by the examples with various lamination schemes, elastic modulus ratios, aspect ratios and boundary conditions and by the comparison with other results. The effect of the associated boundary conditions in different TSDTs is also evaluated through numerical results. The influence of the higher-order and coupling mass matrices on the frequencies of higher-mode vibration is conducted too. The numerical results clearly demonstrate that the present plate element is not only very efficient but also capable of yielding accurate natural frequencies of both the fundamental and the higher-mode vibrations of laminated composite plates.

Forced Vibration Study of Carbon Nanotubes Using Non-Local Elasticity and Timoshenko Beam Theories

Forced vibrations of the single wall carbon nanotubes (SWCNTs) using the non-local elasticity theory and Timoshenko beam theory is studied. Governing equations for the vibration response of the carbon nanotubes are derived employing Eringen’s nonlocal elasticity theory. Analysis is carried out for both EulerBernoulli beam theory and Timoshenko beam theory. Present forced vibration results for Euler-Bernoulli are in good agreement with those reported in literature. Effects of (i) nonlocal parameter (ii) length of the carbon nanotube and (iii) modes of vibration on the vibration response of the carbon nanotubes are investigated. The effect of nonlocal parameter on the vibration response are significant for small size carbon nanotube and higher modes of vibration.

Selection of Wood Based on Acoustic Properties for the Solid Body of Electric Guitar

For the purpose of making of a solid body of an electric guitar the acoustic- and mechanical properties of walnut- (Juglans regia L.) and ash wood (Fraxinus excelsior L.) were researched. The acoustic properties were determined in a flexural vibration response of laboratory conditioned wood elements of 430 × 186 × 42.8 mm used for making of a solid body of an electric guitar. The velocity of shear- and compression ultrasonic waves was additionally determined in parallel small oriented samples of 80 × 40 × 40 mm. The research confirmed better mechanical properties of ash wood, that is, the larger modulus of elasticity and shear modules in all anatomical directions and planes. The acoustic quality of ash wood was better only in the basic vibration mode. Walnut was, on the other hand, lighter and more homogenous and had lower acoustic- and mechanic anisotropy. Additionally, reduced damping of walnut at higher vibration modes is assumed to have a positive impact on the vibration response of future modelled and built solid bodies of electric guitars. When choosing walnut wood, better energy transfer is expected at a similar string playing frequency and a structure resonance of the electric guitar.

In-plane and out-of-plane free vibration analysis of thin-walled box beams based on one-dimensional higher-order beam theory

In this paper, the accurate free vibration characteristics of thin-walled box beam are discussed and the kinematic model is established by using fine shear deformation theory. The model adopts the in-plane and out-of-plane displacement fields including extension, torsion, warping and distortion, as well as the transverse shear due to bending and warping due to torsion. One-dimensional high-order beam theory is applied to the dynamic solution of thin-walled box beam, and the analytical solution of high free vibration modes of multi-deformation coupled modes under different boundary conditions is derived. The results show that warping, distortion and shear deformation play an important role in the free vibration characteristics of thin-walled box beam, and the validity of the model is verified. In addition, finite element software (ANSYS) is used for finite element simulation. The application of vibration mode in the structure design of thin-walled box beam is summarized, especially in the case of higher natural frequency. The calculation method is in good agreement with the finite element results.

Formation Mechanism and Excitonic Luminescence of Supercritical-Fluid-Synthesized ZnO Nanoparticles

Extensive research on nanosized ZnO has proven that its optical properties are challenging to control due to a number of possible defects producing various emissions in the visible range. Our group proposed a low-temperature, supercritical-fluid-driven synthesis of isotropic nanosized particles that exhibit a unique and unprecedentedly pure excitonic emission, comparable to that of single crystals. The present article reports the growth mechanism at the origin of the unexpectedly pure excitonic emission as well as a more detailed study of its optical properties at liquid helium temperatures. The ZnO phase is obtained via the thermal decomposition of an intermediate ZnO2 phase. No bulk defect luminescence is detected, and the synthesis route leaves a “ZnO2-like” surface able to neutralize the formation of surface defects, which can contribute to visible emissions. The luminescence measurements were performed at liquid helium temperature to enable the identification of excitons. The investigation of the photoluminescence properties confirms a strong excitonic emission in the UV region with no visible band and sheds light on a phonon coupling with the E2 high vibrational mode.

Earthquake perception data highlight natural frequency details of Italian buildings

As the distance from an earthquake increases, the percentage of people who do not feel it also increases. The average transition distance between “felt” and “not felt” reports is mainly determined by the magnitude and depth of the earthquake, but it also depends on the observation floor and building height. Buildings act as resonators and can amplify the shaking at specific frequencies. We analyzed over 286,000 crowdsourced reports to study the effect of floor and building height on earthquake perception. We found that, compared to average values, there is an increase in the percentage of “felt” reports on the highest floors and a decrease in the lowest floors of buildings of all heights. We determined the range within which an observer is likely to feel an earthquake (perception boundary) and examined how it varies with magnitude. We found that as the building height increases, people on higher floors perceive medium to high magnitude earthquakes progressively better than lower magnitude ones. We compared the perception boundary with a model of seismic response spectra to estimate the vibration frequency perceived by observers on each floor/building height combination. Our results show that the value of the fundamental period increases with building height for the top floor, and that higher vibration modes become more evident for buildings with more than 6 stories. In addition, we observed that the height of the building also affects the vibration of the basement, with the frequency tending to decrease as the building height increases. Concerning macroseismic intensity estimation, we show that in tall buildings, observations made on both the upper and lower floors must be considered outside the normal range, and that earthquake perception also changes as a function of magnitude and distance, pointing out the importance of collecting an adequate number of observations to sample different locations of observers.

Method for efficient excitation of selective vibration modes in pulsed laser photothermal actuation

Photothermal excitation based on thermoelastic mechanisms is widely used in non-destructive testing, precision operations, and driving micro-resonators. The narrow drive bandwidth of the high vibration mode in photothermal excitation limits its application to multi-mode drives. Controlling the laser’s irradiation position is an effective solution. In this study, we build a theoretical model to achieve selective and efficient excitation of different flexural vibration modes of beams with different supports. The model can be extended to other thermal and physical boundaries, which is validated by numerical simulations and experimental results. The results show that higher modes with complex periodic shapes can be efficiently excited by focusing the laser at the peak of the absolute value of the second derivative of the flexural mode while focusing the laser at the inflection point of the mode shape will result in extremely small amplitudes. Our study indicates that the thermal gradient plays a vital role in the oscillation of the beam. The conventional view assumes that the resonance of the photo-thermal excitation beam is caused by the local expansion and contraction of the material, which cannot completely explain the dependence principle of the photothermal vibration on the laser irradiation position. To investigate the mechanism of beam resonance under laser excitation, three excitation modes, unidirectional excitation, bidirectional in-phase excitation, and bidirectional anti-phase excitation, were established, and the conversion process of optical energy to mechanical energy under laser excitation was analyzed. These results provide new options for optimal excitation and multi-mode energy flow control in photothermal driving.

A Future with Machine Learning: Review of Condition Assessment of Structures and Mechanical Systems in Nuclear Facilities

The nuclear industry is exploring applications of Artificial Intelligence (AI), including autonomous control and management of reactors and components. A condition assessment framework that utilizes AI and sensor data is an important part of such an autonomous control system. A nuclear power plant has various structures, systems, and components (SSCs) such as piping-equipment that carries coolant to the reactor. Piping systems can degrade over time because of flow-accelerated corrosion and erosion. Any cracks and leakages can cause loss of coolant accident (LOCA). The current industry standards for conducting maintenance of vital SSCs can be time and cost-intensive. AI can play a greater role in the condition assessment and can be extended to recognize concrete degradation (chloride-induced damage and alkali–silica reaction) before cracks develop. This paper reviews developments in condition assessment and AI applications of structural and mechanical systems. The applicability of existing techniques to nuclear systems is somewhat limited because its response requires characterization of high and low-frequency vibration modes, whereas previous studies focus on systems where a single vibration mode can define the degraded state. Data assimilation and storage is another challenging aspect of autonomous control. Advances in AI and data mining world can help to address these challenges.

Performance of wire rope damper in vibration reduction of stay cable

This paper systematically investigates the novel application of wire ropes as a damper rather than as an isolator to reduce the wind-induced high-mode vibration of stay cables. Three-direction cyclic loading tests, including tension–compression direction, shear direction, and roll direction, are conducted to clarify the damping behavior of the proposed wire rope damper. The wire rope damper exhibits asymmetric hysteretic characteristics in the tension–compression direction, while the hysteresis loops in the shear and roll directions are symmetrical. A modified normalized Bouc-Wen model is presented to describe the multi-directional hysteretic characteristics of the wire rope damper. An analysis method considering the nonlinear damping behavior is developed in this study to overcome the limitations of the traditional analysis using an equivalent damping coefficient. The proposed analysis method is validated against the physical experiments. The proposed wire rope damper system was installed on the Su-Tong Yangtze River Bridge to reduce the high-mode vortex-induced vibration of the stay cable. The field monitoring data demonstrate that the proposed wire rope damper can significantly reduce the in-plane and out-of-plane vibrations. The effect of the wire rope damper on the cable vibration control is further examined using the proposed analysis method. The finite element results further demonstrate the effectiveness of the wire rope damper in high-mode vibration reduction of stay cables. The features of the wire rope damper, such as multi-directional damping, broadband applicability, and simple configuration, are beneficial to its application in cable vibration control.

A study into the FSI modelling of flat plate water entry and related uncertainties

This paper presents systematic comparisons of experiments against fluid structure interaction (FSI) simulations for flat water plate entry. Special focus is attributed on hydroelasticity and air trapping effects, quantification of the experimental and numerical uncertainties and the validity of modelling assumptions for the prediction of bottom slamming induced loads. Consequently, the American society of Mechanical Engineers standard for Verification and Validation is used to estimate the errors. Numerical and experimental results agree favourably. It is shown that pressures and strains may be prone to spatial effects that lead to minor deviations between experiments and simulations. High frequency vibration modes and model boundary conditions may also influence the results.