Transient Dynamic Finite Element Analysis Research Articles

Research on the Vibration Behavior of Ring–Block Friction Pair Made of Materials of Water-Lubricated Rubber Bearing under Special Operating Conditions

A water-lubricated rubber bearing (WLRB) is prone to generate frictional vibration noise under special operating conditions, which seriously affects the acoustic stealth performance of warships and threatens their navigation safety. Meanwhile, the main factor affecting the frictional vibration behavior of a WLRB is the materials of the friction pair. Therefore, this work selects a friction pair composed of a copper ring and a rubber block as the research object and studies the frictional vibration behavior of the ring–block friction pair under low-speed and starting conditions. The real friction coefficient curve is used to establish a transient dynamic finite element analysis model for the ring–block friction pair. The effects of the load, friction coefficient, and Young’s modulus on the frictional vibration behavior under special operating conditions are studied. The analysis’s results show that the frequency of the medium-high frequency friction-induced vibration disappears under low-speed operating conditions when the friction coefficient is below 0.1. During the startup process, even if the friction coefficient is very low, the medium-high frequency friction-induced vibration still exists. The research results provide ideas for future theoretical research and guidance suggestions for engineering practice.

Assessment of the Blasting Efficiency of a Long and Large-Diameter Uncharged Hole Boring Method in Tunnel Blasting Using 3D Numerical Analysis

Cut blasting is one of the most essential processes to reduce blast-induced vibration in tunnel blasting. The long and large-diameter uncharged hole boring (LLB) method is an example of one of the cut blasting methods, which utilizes large-diameter uncharged holes drilled in the tunnel face. In this study, blasting simulations were performed to analyze its blasting mechanism, and the LLB method and the traditional burn-cut method were simulated to compare their blasting efficiency. A 3D numerical analysis using LS-DYNA code, a highly non-linear transient dynamic finite element analysis using explicit time integration, was used to simulate the blasting process, and a Johnson–Holmquist constitutive material model, which is optimal for simulating brittle materials under dynamic conditions, was used to simulate the rock behavior under blasting. The modified LLB method showed a 3.75-fold increase in the advance per round compared to the burn-cut method, due to the increased formation of long and large-diameter uncharged holes compared to blast holes. This modified LLB method used 30% less explosives, so its failure range was approximately 1.25 times less than that of the burn-cut method, but its advance was approximately 4 times larger than the burn-cut method, which was similar to the original LLB method. This confirmed that the modified LLB method is significantly more efficient in terms of increased blasting efficiency (particularly the advance per round) as well as reduced blast-induced vibration, compared to the traditional cut blasting method.

Multiple damage detection in a cantilever beam using baseline-free operational modal analysis

Operational Modal Analysis (OMA) or output-only modal analysis allows obtaining modal parameters in operational conditions, i.e., without external excitation. While being more challenging than traditional or Experimental Modal Analysis (EMA), OMA allows to monitor the structural health of a structure in cases where EMA is not practical or feasible. This article presents an introduction to an OMA technique based on Frequency Domain Decomposition (FDD) and its mathematical formalism, and demonstrates its potential for detecting damage in a cantilever beam. A transient dynamic Finite-Element Analysis (FEA) under white noise excitation has been performed in ANSYS Workbench to obtain the acceleration responses of the system. The numerical accelerometers signals along the beam are used for the OMA analysis and multiple cracks are analyzed at different positions along the beam. The technique used for damage detection is Curvature Mode Shape (CMS) analysis, using only the information of the damaged structure, making it a baseline-free method. The technique is shown to be capable of correctly detecting and locating the different damages analyzed.

Fatigue Life Prediction for the Steel Passenger Car Wheel in the Dynamic Cornering Fatigue Test

This study aims to establish an effective method for predicting the fatigue life of an automotive wheel in the accelerated dynamic cornering fatigue test. The test was simulated by linear transient dynamic finite element analysis, in which a rotating force of constant magnitude was applied to the moment arm tip to simulate the rotational bending effect on the wheel, with the wheel being fixed. Furthermore, transient strain histories of the elements were obtained and the critical elements with the largest amplitudes in their respective steady radial strain histories were found. The steady radial strain histories of all the critical elements were processed based on the local stress-strain approach, and the shortest simulated fatigue lives were taken as the predicted wheel fatigue lives. The predicted fatigue life was in good agreement with the average real-world test life of the investigated wheel.

Numerical Analysis of Shock Initiation on Highly Energetic Material LX-04

The paper presents investigation of shock initiation effects on highly energetic material LX-04, an HMX based one, by a blunt brass projectile using numerical modelling methods implemented in LS-Dyna software. Multi – Material Arbitrary Lagrangian Eulerian (MM-ALE) formulation has been used to provide the possibility of fulfilment of the elements with multiple materials accordingly to multiple phases of the composition detonated. The work is focused on LS-Dyna’s equation of the state keyword *EOS_IGNITON_AND_GROWTH_IN_HE. Proper comparison with experimental data is presented. The introduction into the subject of highly nonlinear transient dynamic finite element analysis, possibilities, and superiority of this kind of modelling are being discussed. Reasons of sustaining the need of data by numerical solutions rather than experimental handling in military applications are given. Some of typical technical issues, occurring during such a fast-performing phenomenon, and the need of experimental validation of the models are typed together with detonation-state determination’s observation capabilities.

Effects of material and coefficient of friction on taper joint dental implants

PurposeThe aim of this study was: (1) to compare the coefficients of friction between commercially pure titanium (cpTi), titanium (Ti) alloy, and yttria-stabilized zirconia (YSZ) and: (2) to investigate the dynamic behavior of an implant system before, during, and after loading, by transient dynamic three-dimensional finite element analysis (FEA). MethodsCoefficients of friction were measured by a ball-on-disk frictional wear testing device. The preload in the screw shaft was calculated from geometric parameters. Two abutment model designs were created, namely a Ti alloy abutment model with a porcelain-fused-to-metal super structure and a YSZ abutment model with a porcelain-fused-to-zirconia super structure. Transient dynamic three-dimensional FEA was performed on ANSYS Workbench Ver. 15.0. ResultsThe coefficients of friction of YSZ/cpTi, YSZ/Ti alloy, Ti alloy/cpTi, and Ti alloy/Ti alloy were 0.4417, 0.3455, 0.3952, and 0.3489, respectively. The preload generated in the abutment screw of the FEA model was set to be 158 N. Significantly differences were not found in the maximum von Mises equivalent stress between the Ti alloy and YSZ abutment models before, during, and after loading. ConclusionThe findings indicate differences in the coefficients of friction of cpTi, Ti alloy, and YSZ before, during, and after loading. Fractures caused by stress did not depend on the use of different materials (Ti alloy and YSZ) at the abutment.

Evolution Mechanism of Wind Vibration Coefficient and Stability Performance during the Whole Construction Process for Super Large Cooling Towers

Wind-induced damage during the construction process and the evolution of damage over time are important reasons for the wind-induced destruction of large cooling towers. In fact, wind vibration coefficient and stability performance will evolve with the construction height and material properties over time. However, the existing studies generally ignore the impact of wind load and structural performance during the construction period. In this study, we built the 3D physical model separately for all eight construction stages a super large cooling tower which is being currently constructed and stands 210 m. The dynamic characteristics of the cooling tower were analyzed in each stage. First, the flow field information and 3D time history of aerodynamic forces were obtained for the whole construction process using large eddy simulation (LES). Full transient dynamic finite element analysis was used to calculate the dynamic responses of the tower under the real-time changes of wind loads during the whole construction process. Five calculation methods were used to trace the evolution of wind vibration coefficient during the whole construction process of the super large cooling tower. Then the formula for wind vibration coefficient changing with the construction height was fitted. The differential values of wind vibration coefficient during the whole construction process of the cooling tower were discussed by taking the meridional axial force as the objective function. On this basis, the influence and working mechanism of wind vibration coefficient, concrete age, construction load, geometric nonlinearity, internal suction force on buckling stability, and ultimate bearing capacity of the cooling towers were investigated. This research provides an enhanced understanding on the evolution of wind-induced stability performance in super large cooling towers and a methodology to prevent wind-induced damage during the construction process.

Composite wall test-chamber assessment for hydrogen blast loads

Simplified energy based analytical models and close form solutions are used to evaluate the limiting quasi-static and impulsive over-pressure transient response of a composite wall test-chamber, which is validated and confirmed with experimental observations using controlled hydrogen combustion tests. Further a detail three-dimensional transient finite element simulation is presented to compare the test results with the numerical results. The effectiveness of evolved procedures is highlighted in the context of the blast resistance evaluation of experimental facilities besides the other important infrastructures that might be subjected to hydrogen blast loads. Despite the known limitations of the simplified analytical models and close form solutions, its usefulness is emphasized to develop fundamental understanding for arriving at sound engineering judgment for conducting blast experiments in a safe manner. With this background, the interpretation of the associated detail three-dimensional transient dynamic finite element analysis results is shown to be consistent and in good agreement with the test observations.

Structural response analysis of slamming impact on free fall lifeboats

The evaluation of impact induced slamming loads experienced by ships and offshore structures using advanced fluid structure interaction methods may be a challenging task involving complex and time consuming engineering solutions. This is the reason why to date the application of well understood and validated quasi-response approaches remains the most rational alternative used by experts for preliminary design assessment. Based on a benchmark study carried out by the International Ship and Offshore Structures Congress Technical Committee II.1 on Quasi-Static Response this paper demonstrates the practical use of “quasi-response” prediction methods for the assessment of impact loads on modern free fall lifeboats. The case study presented is considered relevant in terms of technical background and ship design for safety. Following a brief review rationalising the practical relevance of the engineering solutions examined, the influence of high speed impact is evaluated using linear-elastic and nonlinear beam models, as well as a nonlinear transient dynamic finite element analysis idealisation. Comparisons of the methods presented against experimental results led to the conclusion that the nonlinear quasi-dynamic beam approach accounts for the influence of the dynamic effects of strain by suitably idealising the effects of nonlinear geometric stiffness. It may therefore be more appropriate to employ this approach at preliminary stage, especially when conducting comparisons against simplistic linear methods used for rigid structures (e.g. stiffened steel and aluminium panels), or advanced nonlinear finite element analysis and other multi-physics methods that may be computationally complex and time consuming.

Large Deformations and Tearing of Circular Plates and Plate-Tube Structural Combinations under Impulsive Loading

Response of circular plates under transverse impulsive load time history using a transient dynamic finite element analysis methodology employing progressive degradation has been presented. Experimental results by Nurick et al. for the prediction of onset of thinning and subsequent tearing at the boundary of clamped circular plates subjected to uniformly loaded air blasts have been used to compare and validate the FE model and simulation procedure in ANSYS. The Mode II failure in respect of clamped circular plates has been simulated using a rupture strain criteria. Mode III failure of plastic shear sliding has been considered with a shear strain failure model as proposed by Wen et al. where in the circular plate parameters have been used. A progressive degradation approach employing a stiffness reduction scheme under the FE model setup has been proposed to simulate the initiation and progression of tearing in conjunction with a suitable failure model under mode II and mode III failure. The evolution of deflections, plastic zones, rupture zones and failure modes under the blast loading conditions are found to be in very good correlation with the experimental results of Nurick et al.

Transient Dynamic Finite Element Analysis of the Air-defence Weapon System Mount Assembly of Tracked Vehicle

A detailed finite element model of the existing Air-Defence Weapon System (ADWS) mount assembly of a military tracked vehicle, has been developed in Abaqus/CAE and modal dynamic analyses have been carried out. A mathematical vibration model of the gun recoil system has been developed in Matlab, in order to estimate the transmitted force variation during gun firing as well as the gun recoil. The frequency spectrum of transmitted force variation, has been analysed in correlation with extracted eigen values of the mount assembly, followed by dynamic analysis during rapid firing of 5 rounds. Based on modal dynamic analysis, required design modifications have been carried out by stiffening the mount structure at appropriate locations, and firing accuracies were obtained within acceptable limits. This study would be a useful approach to design of any gun mount assembly.

Crush Behavior of Corrugated Cores Sandwich Panels

The out-of-plane quasi-static compressive behavior of four types of corrugated cores (V-type, U-type, X-type and Y-type core) has been investigated by experiment and FE simulations. By transient dynamic finite element analysis code MSC.Dytran numerical simulations were performed for calculating crushing forces, deformation mode and energy absorption. The FE simulations predict the crush behavior of cores with reasonable accuracy and provide the whole progressive buckling process and deformation modes. Experiment and simulation indicate that the U-type core, V-type core and X-type core structures show excellent crushing resistance performance and energy absorption characteristic. The crush performance of the Y-type core structures is relatively poor because of bending mode.

FEM Investigation of Machinability Properties of SiCp/Al Composites

In this paper, a transient dynamic finite-element analysis was carried out to investigate the effects of the cutting speed on cutting force, cutting temperature, and the chip-shear angle. The workpiece material is SiCp/Al composites with lager particle and high volume fraction. The results show that the cutting force decreased, while the cutting temperature and chip-shear angle increased evidently with increasing of cutting speed. The results obtained from this study can predict the behaviors of machining SiCp/Al composites very well and the variation trend is agree well with that of the experiments.

Feasibility study of a lunar landing area navigation network deployed by impacting micro-probes

Exploration activities on the lunar surface will require precise knowledge of the position of a robotic or manned vehicle. This paper discusses the use of radio beacons as method to determine the position of a mobile unit on the surface. Previous concepts consider the installation of such equipment by the robot itself. A novel idea is discussed here, namely to use miniaturized radio beacons which are deployed (released) during the descent of the lander on the surface. This idea has three major advantages compared to previous proposals: (i) it avoids the time costly and energy consuming installation of the equipment by a rover. (ii) The impact velocities of the probes are in reasonable range since the probes are deployed at low altitude from the main lander that approaches its final landing site. (iii) The probes can take reconnaissance pictures during their free-fall to the surface. This method will therefore deliver charts of the proximity of the landing area with higher resolution than those done by orbital means. Such information will enable scientists and mission operators to precisely plan robotic excursions (and later Extra Vehicular Activity) through the identification of hazardous areas and spots of interest. The paper will study the feasibility of this system from different aspects. The first section will outline the application scenario and the potential outcome of such a system for the coming phase of lunar exploration. A technological readiness review was done to evaluate if the payload instrumentation for these high velocity impacting probes is available. The second section presents the simulation of the impact process of a preliminary probe model in nonlinear transient dynamic finite element analysis using the Lagrangian hydrocode LS-DYNA. The purpose of this simulation was to evaluate if the beacon is able to communicate with the mobile unit even when buried into the soil. The integration of this payload into coming lunar missions will contribute to the international efforts of lunar exploration with a landing site ad hoc navigation system for robotic or manned excursions.

Shape and sizing optimisation of automotive structures with deterministic and probabilistic design constraints

This paper presents the results of a study on the combined shape and sizing optimisation of automotive structures while examining the effects of different design constraints and associated uncertainties on reliability and efficiency of the optimum designs. Nonlinear transient dynamic finite element analysis is used for full- and offset-frontal crash simulations of a full vehicle model. Surrogate models are developed for the intrusion distance and peak acceleration responses at different vehicle locations based on the material and geometric characteristics of the rail component. The obtained solutions provide insight on the effect of uncertainties in optimum design of automotive structures.

Simulation of dynamic cornering fatigue test of a steel passenger car wheel

This paper aims at seeking a practical and comprehensive method for simulating the dynamic cornering fatigue test of the automotive wheels. The test of a steel passenger car wheel is simulated by combined use of the linear transient dynamic finite element analysis and the local strain approach. A rotating force of constant magnitude is applied to the moment arm tip to simulate the rotating bending effect on the wheel, with the wheel stationary. It is found that only a radial component of the rotating force is needed to obtain the sufficiently accurate radial normal strain histories of the elements located along the radial direction. The strain history of the element whose local stress–strain characteristic keeps linear and closest to the critical element is applied to predict the fatigue life of the critical element with Neuber’s rule and local strain approach, which is quite close to the test results.

Delamination in Hybrid FRP Laminates under Low Velocity Impact

The present article deals with assessment of impact-induced delamination in hybrid fiber reinforced plastic laminated composites. Studies have been conducted on single material graphite/epoxy and kevlar/epoxy laminates as well as graphite/epoxy-kevlar/epoxy hybrid laminates to determine their responses to impact loading. Eight-noded layered solid elements have been used for finite element modeling of FRP laminates. Newmark-method along with Hertzian contact law has been used for transient dynamic finite element analysis. Stresses at the interfaces have been calculated using least-square formulation proposed by Hinton and Campbell. Based on the stresses calculated, delamination at the interfaces have been assessed using appropriate delamination criterion. It has been observed that even though the contact force magnitude is much less in the case of kevlar/epoxy laminates compared to that in graphite/epoxy laminates, the number of interfaces where delamination occurs as well as the delamination extent is greater in the case of kevlar/epoxy laminates. From the present study it could be observed that kevlar/epoxy-graphite/epoxy laminate is a better choice for guarding against impact-induced failure in laminated composites.

Nonlinear transient dynamic response of damped plates using a higher order shear deformation theory

Damped transient dynamic elasto-plastic analysis of plate is investigated. A finite element model based on a C0 higher order shear deformation theory has been developed. Nine noded Lagrangian elements with five degrees of freedom per node are used. Selective Gauss integration is used to evaluate energy terms so as to avoid shear locking and spurious mechanisms. Von Mises and Tresca yield criteria are incorporated along with associated flow rules. Explicit central difference time stepping scheme is employed to integrate temporal equations. The mass matrix is diagonalized by using the efficient proportional mass lumping scheme. A program is developed for damped transient dynamic finite element analysis of elasto-plastic plate. Several numerical examples are studied to unfold different facets of damping of elasto-plastic plates.

Deformation and tearing of circular plates with varying support conditions under uniform impulsive loads

Transient dynamic finite element analysis of circular plates with varying support configurations under uniform single square wave form impulsive load has been carried out in FEA package ANSYS. Experimental results of Teeling-Smith and Nurick [The deformation and tearing of thin circular plates subjected to impulsive loads. Int J Impact Eng 1991;11(1):77–91] and Nurick et al. [Tearing of blast loaded plates with clamped boundary conditions. Int J Impact Eng 1996;18(7–8):803–27] for the onset of thinning and tearing at the boundary of clamped circular plates subjected to uniformly loaded air blasts have been used to compare and validate the numerical simulation and procedure. The Mode II failure with respect to clamped circular plates has been simulated using a rupture strain criteria. Mode III failure or plastic shear sliding, has been considered using a shear strain failure criteria as proposed by Wen and Jones for plates. A stiffness reduction scheme has been proposed to decide on the initiation and progression of tearing in conjunction with suitable failure model under Modes II and III. The evolution of deflections, plastic zones, rupture zones and failure modes under the blast loading conditions are found to match well with the experimental results. The validated numerical model has further been used to study the effect of plate thickness on the deformation and tearing response of the circular plates subjected to impulsive loads. The deformation, tearing and shock absorption response of clamped circular plates under uniform impulsive loads with ring support of varying edge configurations at the boundary have also been numerically studied. Further, the response of circular plate–tube combination with varying boundary support configurations has been studied. The plate has been considered at the mid-span of the tube of length equal to the plate diameter with the ends of the tube modelled as clamped. The numerical model has been used to study the effect of tube thickness variations on the deformation and tearing response of the circular plate under shock loads. The response of tube–plate combinations under uniform impulsive loads with ring support at the plate–tube junction have also been numerically studied.

Delamination of laminated fiber reinforced plastic composites under multiple cylindrical impact

In the present paper a 3D finite element analysis has been performed for assessing delamination at the interfaces of graphite/epoxy laminated fiber reinforced plastic composites subjected to low velocity impact of multiple cylindrical impactors. Eight nodded layered solid elements have been used for the finite element analysis of fiber reinforced plastic laminates. Newmark-β method along with Hertzian contact law has been used for transient dynamic finite element analysis and an algorithm has been developed for determining the response of the laminated plate under the multiple impacts at different time. Appropriate delamination criterion has been used to assess the location and extent of delamination due to multiple impacts. A study has been carried out to observe the effects of important parameters on the impact response of the laminate and the delamination induced at the interfaces. It has been observed that the contact force magnitude as well as delamination at the interface are greatly influenced by the time interval between successive multiple impacts.