Dynamic Load Analysis Research Articles

The dynamic loads of mobile continuous earthmoving machine during the working body lock

working body is locked significant dynamic loads appear that influence the drive shaft and might lead to the machine breakdown. Preliminary approximate calculation of these loads is made according to oneor two-mass dynamic loads. For more detailed and precise analysis of dynamic load in drive shaft elements of the earth moving machines it is necessary to review the multimass model machine element movement. Goal. The aim of research is definition of the dynamic load and working out methodology that appears in the continuous earth digging machine elements during working body lock. Methodology. The discreet dynamic system dynamic and mathematical model construction is performed by means of the programming language Modelica. The model relevance is assessed via a two-mass model analytical solution. Results. Drive shaft element loading is assessed via the dynamic coefficient, which depends on kinematic, flexible and inertial machine parameters. Originality For the first time the continuous earth digging machine dynamic model that enables the automobile chassis drive shaft to interact with the continuous digging chain is constructed. It was determined that the drive shaft dynamic loading parameter correlation change upon the earth digging machine working body meaningful parameters. With designed model usage, the input data for transmission element engineering calculation was defined and the automobile basic chassis construction, equipped with the continuous digging chain. Practical value. The obtained dynamic factor value and developed methodology can be applied during continuous earth moving machine designing and calculation. Dynamic load decrease is possible through shaft stiffness and rotating mass inertia adjustment, and also by introducing elastic protecting frictional coupling with a controlling device.

Сравнительная оценка динамической нагруженности длиннобазных вагонов-платформ

Objective: Comparative analysis of dynamic loading of long-base fl atcars on bogies of various types. Methods: Comparison of experimental data of running strength tests of long-base fl atcars obtained by the Engineering Center of the rolling stock in the conditions of a test site on the Belorechensk–Maikop track of the North Caucasian Railway was carried out. The division of platform cars into conditional groups was used depending on the truck. Results: It was found that the use of constant contact side bearers in the bogie design reduces the dynamic loading of the fl atcar on straight track sections by 1,2–1,5 times. The obtained dependences of the coeffi cients of vertical dynamics for the center and side sill showed that for all fl at cars they are identical in nature and differ only in the level of values. The use of modern bogies with nonlinear spring suspension and constant contact side bearers in long-base fl atcars leads to a decrease in the dynamic loading of the frame by an average of 15–25 %, thereby reducing the likelihood of possible damage to the fl atcar in operation. Practical importance: It is shown that it is necessary to clarify the normative dependence of the speed distribution of the vertical dynamics coeffi cients for fl atcars on various types of bogies. Its correction will improve the accuracy of determining the parameters of the stress-strain state of the platform car frame. The comparison results can be recommended for practical use in assessing the strength and fatigue resistance of the fl at car structure

Effects of Vibration Isolator on Compound Planetary Gear Train with Marine Twin-Layer Gearbox Case: a Dynamic Load Analysis

This study aims to take the compound planetary gear train as an example to investigate how the vibration isolator affects the dynamic characteristics of the gear system. The dynamic parameters are obtained from the finite element model of the gearbox case with the vibration isolators by the substructure method. The lumped mass method is used to construct the systematic coupled dynamic model of the compound planetary gear train with the marine twin-layer gearbox case. The dynamic response of the coupled system is calculated by the numerical calculation method of the Fourier series. The number of vibration isolators negatively affects the bearing forces of the input shaft, output shaft, and planets. The influence of the number of vibration isolators on LSCs is different in the differential stage and the encased stage. When the vibration isolators stiffness is less than 200 N/μm, the stiffness of the vibration isolator has a significant effect on the bearing forces of the input shaft, output shaft, and planets. The increase in the stiffness of the vibration isolator would increase the LSCs of the differential stage and decrease the LSCs of the encased stage. The number and stiffness of the vibration isolator have influences on the bearing forces and the LSCs. Compared with the LSCs in the differential stage, the LSCs in the encased stage are more sensitive to the number and stiffness of vibration isolators.

An approach to mixed-fidelity system simulation of extravehicular activities

The National Aeronautics and Space Administration (NASA) is currently developing the next generation of spacesuits for use in future exploration missions. This effort, referred to as the Exploration Extravehicular Mobility Unit (xEMU), has been underway since 2015 with the goal of demonstrating the new technologies during a mission to the International Space Station (ISS).Due to the complexity of the xEMU system, and particularly its portable life support system (PLSS), computer simulations are heavily relied on in the development process, from dynamic loads analysis to software verification. The models of the physical systems that are currently being used for system-level simulations are mostly empirical, where the underlying formulas are mathematical fits to test or simulation data. An advantage of this approach is the fact that these models are very performant and can be used in real-time applications such as user interface testing and operator training.The research presented in this paper describes a different approach to modeling and simulation. A simulation tool focused on life support systems for human spaceflight in general and PLSSs in particular has been under development at the Technical University of Munich (TUM) since 2006. The spacesuit specific variant of this tool is called The Virtual Spacesuit (V-SUIT) and is now being utilized in the current spacesuit development process at the NASA Johnson Space Center (JSC). In contrast to the previously mentioned empirical models, V-SUIT uses a first-principles-based, bottom up modeling approach, where basic physical, chemical or biological effects are modeled at the lowest level and the component and system models are created using these fundamental building blocks. This enables the simulation to account for effects, and especially off-nominal situations, that may not be within the range of validity of the empirical models.This paper presents the structure of and the rationale behind V-SUIT itself as well as a status report on the ongoing effort to integrate it with the existing simulation systems in use at JSC, which is based on Trick/GUNNS. As a proof of concept, a single component model from V-SUIT, that of the spacesuit water membrane evaporator (SWME), has been integrated with NASA's simulation tool.Results include comparisons of the performance of the two simulation systems and a description of challenges that were encountered during implementation. The paper closes with an outlook towards the future developments that are planned for V-SUIT within the xEMU development program.

Response of Tall Structures Along Face Exposed to Blast Load Applied at Varying Distance

Blast loads caused by explosives are unexpected loads. These loads cause huge damage to the structure and decrease the strength and durability of structure, especially for elevated buildings. Therefore study of such loads is of major importance. In the present study, G+10 floors with second, third and end bays is modelled using ETABS and sudden impact dynamic load analysis is carried out. The analysis is carried out on the face directly exposed to the blast load for 7 building models. The blast loads are obtained with the help of TM5-1300 manual as well as ATBLAST software and Structure is designed in ETABS software by non-linear time history analysis. The results of this study help in understanding the behaviour of tall structures in terms of drift, displacement, joint acceleration and shear. Observations show that Model 7 is found to have extreme shear, storey displacement and inter-story drift. The research on examination of tall structures subjected to explosion is helpful in coming up with a better, cost-effective design for blast resistant structures.

The double‐tree method: An O(n) unsteady aerodynamic lifting surface method

SummaryTwo new methods for reducing the computational cost of the unsteady vortex lattice method are developed. These methods use agglomeration to construct time‐saving tree structures by approximating the effect of either a group of vortex rings or query points. A case study shows that combining the two new O(n·log n) tree methods together results in an O(n) method, called the double‐tree method. Other case studies show that the trade‐off between accuracy and speed can be easily and reliably controlled by the agglomeration cutoff distance. For a flat plate with 5 × 200 panels analyzed over 20 time steps, the double‐tree method is 7 times faster than the unsteady vortex lattice method with a <5% difference in the force distribution and total lift coefficient. The case studies suggest that the computational benefit will increase for the same level of accuracy if the size of the problem is increased, making the method beneficial for full‐aircraft analysis within optimization or dynamic load analysis, where the computational cost of the unsteady vortex lattice method can be large.

Nonlinear analysis of dynamic loads of the model haulm removing working body

Significant rotation speeds are required for the qualitative removal of leaf-stem mass from the field when using a rotating working body. An urgent task is to obtain data to evaluate the nonlinear effect of forces on the working body when removing leaf-stem mass. In the article, the degree of influence of the weight of the stems of the leaf-stem mass and centrifugal forces acting on the top-working working body using non-linear dynamic analysis was studied. The implementation of computer simulation was achieved using the CAD-CAE SOLIDWORKS system. As a result of the nonlinear analysis in SOLIDWORKS Simulation, the results of the stresses, displacements, and deformations acting on the top-working working body model were obtained, which made it possible to identify weak points of the working body. The analysis of the obtained data revealed the influence of centrifugal force and weight of the cut leaf-stem mass on the knives of the working body of the haulm machine, which will allow taking these effects into account in the developed design.

A New Method to Assess Coal Burst Risks Using Dynamic and Static Loading Analysis

Mining-induced seismicity is one of the dynamic energy sources that can trigger coal burst. This paper presents a new methodology to assess coal burst risks under different loading conditions by examining seismic energy attenuation and fracture size. Two new indices are proposed: (1) Dynamic Load Index (DLI) quantifies the magnitude of dynamic loading induced by seismic events, based on the relationships between the seismic energy, peak particle velocity and dynamic stress; (2) dynamic–static loading assessment index, $$I_{\text{PD}}$$, links the DLI with passive velocity tomography (PVT) to assess the coal burst risks in a longwall panel under dynamic and static loading. A total of 3080 seismic records were examined to validate $$I_{\text{PD}}$$ in a typical burst-prone longwall panel in China. Based on the rate of occurrence of high-magnitude seismic events, $$I_{\text{PD}}$$ thresholds were determined to identify low-, medium- and high-risk coal burst zones. Using this new zoning approach, coal burst risks were assessed in the same longwall panel while mining through a fault structure. The proposed risk classes correlated well with the recorded high-magnitude seismic events with energies over 10 kJ. The analysis indicated that 69% of the high-magnitude events occurred in the high-risk zones, where $$I_{\text{PD}}$$ was between 0.35 and 1; and 31% of the events occurred in the medium-risk zones, where $$I_{\text{PD}}$$ was between 0.2 and 0.35.

Mechanical Analysis of the ROPS Test Bench for Mining Dump Truck

The static and dynamic load analysis of ROPS was achieved by the finite element method, and the distribution law of stress and deformation was obtained, meanwhile, the feasibility of simulation analysis was discussed. It is beneficial to explore the design and improvement of similar ROPS in the future.

Dynamic load and stress analysis of a large horizontal axis wind turbine using full scale fluid-structure interaction simulation

A dynamic load and stress analysis of a wind turbine is carried out using transient fluid-structure interaction simulations. On the structural side, the three 50 m long commercial glass-fiber epoxy blades are modelled using shell elements, accurately including the properties of the composite materials. On the fluid side, a hexahedral mesh is obtained for every blade and for the hub of the machine. These meshes are then overlaid to a structured background mesh through an overset technique. The displacements prescribed by the structural solver are imposed on top of the rigid rotation of the turbine. The atmospheric boundary layer (ABL) is included using the k-epsilon turbulence model. The computational fluid dynamics (CFD) and computational solid mechanics (CSM) solvers are strongly coupled using an in-house code. The transient evolution of loads, stresses and displacements on each blade is monitored throughout the simulated time. The ABL induces oscillating axial displacements in the outboard region of the blade. Furthermore, the influence of gravity on the structure is accounted for and investigated, showing that it largely affects the tangential displacement of the blade. The oscillating deformations lead to sensible differences in the torque provided by each blade during its rotation.

Development of high fidelity reduced order hybrid stick model for aircraft dynamic aeroelasticity analysis

This paper presents a new high fidelity reduced order modeling methodology based on a hybrid stick model representation approach. Here, the traditional stick model developed by the unitary loading method is augmented by residual mass and stiffness matrices that account for the dynamic imparity between the stick model and the global finite element model, within a frequency range of interest, as well as the degrees of freedom coupling commonly ignored by the simplified stick model. The new method offers the handling flexibilities of the conventional stick model as well as the high dynamic accuracy of matrix based model order reduction methods such as the Guyan and the Craig-Bampton condensation techniques. Retaining the stick model in the proposed hybrid model representation intuitively enables aerospace development engineers to, accurately and efficiently, optimize the airframe mass and stiffness distribution for aircraft loads minimization and performance maximization without the need to engage an expensive global finite element model in such highly iterative analyses. Two hybrid stick models are presented in this paper that are developed based on the Guyan and the Craig-Bampton reduction methods. A case study is presented where the hybrid stick models developed along with their conventional stick model counterpart are employed in the dynamic aeroelasticity loads analyses of a Bombardier aircraft platform. Using monitor points method, the extracted aeroelastic loads using the reduced order models are compared against those generated employing the aircraft global finite element model. The dynamic characteristics of the reduced order models are also assessed based on their modal characteristics using modal assurance criteria along with their loads modal participation factors. Results obtained show that the developed hybrid stick models have superior dynamic characteristics compared to the conventional stick model.

Influence of the Structure of the Cross-section of Load-bearing Structures on Their Deformation during Emergency Actions

The paper deals with the issues of destructure modeling for constructive systems of reinforced concrete framing buildings. It is considered the widely using in practice framework of interspecific appliance for multi-storey buildings and structures on the basis of protection against progressive collapse. The results of dynamic additional loading analysis for girders of considering reinforced concrete framework at sudden structural transformation of constructive system are presented. It is obtained that at accidental impact and fragile destruction of tensiled concrete the coefficient of dynamic increasing of internal forces in tensiled reinforcement of reinforced concrete elements depends on the percent of reinforcement in cross section, prestressing level and topology of structure. It is proposed to calculate without of structural dynamic methods on the energetic basis the coefficient of dynamic increasing of internal forces in structures at sudden removal of a bearing element and cracking.

Dynamics strength analysis and test for pipe structuresof aerospacecrafts

The pipelines of aerospacecrafts have characteristics of light and thin structures, severe mechanical environment, high operating stresses and easy to cause low cycle fatigues, and they have broken down in flight for many times. With the development of aerospacecrafts for lightness, reuseable and high reliability, the pressing requirements of pipelines change from environmental adaptability qualitative check to dynamic strength quantitative evaluation. This article firstly introduces the fundamental principles and applications of dynamic load analysis methods for pipelines base on the Miles formula, the modal root mean square (RMS) value, etc., and uses it to guide the dynamic design of pipelines. Then basing on engineering practices, it summaries the theoretical methods and technical key points of the Steinberg fast assessment and the frequency domain fatigue analysis base on statistics model, etc., which are always used in the dynamic strength analysis of pipelines. Finally, combining with the investigation status of design, analysis and test for pipeline dynamic strength in aerospace field, it outlooks the engineering and scientific problems needed to be studied further.

Theoretical Analysis of Low-Frequency Dynamic Load and Research on the Algorithm for Weighing Accuracy Improvement

Theoretical Analysis of Low-Frequency Dynamic Load and Research on the Algorithm for Weighing Accuracy Improvement

Computational analysis of blast loaded composite cylinders

Explosion-resistant containers and chambers show promise for the safe storage and disposal of explosive materials and munitions. Light-weight explosion proof vessels, that are made of fiber-reinforced composite materials, are of specific interest, as their decreased mass allows for an ease in transportation. When developing fiber-reinforced composite structures for dynamic loading, efficient and reliable computational analysis techniques are required. The objectives of this study deal with developing a computational methodology that can be implemented when designing blast loaded composite structures. Specifically, efficient analysis procedures to predict large scale deformation and composite failure in dynamically loaded composite structures are developed for use with LSTC's LS-DYNA. In the process of developing the modeling methodology, a survey of the blast modeling methods available within LS-DYNA is completed and a recommendation is made considering both accuracy and computational cost. The developed methods are then used to simulate the blast loading and response of small, hollow composite cylinders, and the measured results of instrumented explosive tests are used for model validation.

An open-source comprehensive numerical model for dynamic response and loads analysis of floating offshore wind turbines

This paper presents the development of a comprehensive open-source numerical model to study the dynamic response and load analysis of floating offshore wind turbines. The model accounts for the wind inflow, rotor aerodynamics, multibody structural model of the system, wave and current kinematics, hydrodynamics, and mooring-line dynamics. This coupled simulation tool can be used for analysis, optimization and preliminary design to determine the technical and economic feasibility. Several verification and validation cases are performed to show the correctness of the numerical simulations. The results show that the proposed approach provides an accurate estimate of the wind turbine dynamics and loads. The simulation tool is then applied in the analysis of a 5 MW wind turbine aimed to characterize the dynamic response and to identify potential loads and instabilities resulting from the dynamic couplings between the turbine and the external conditions. This open-source fully coupled aero-hydro-elastic model provides a modular framework to enable investigating a variety of wind turbine configurations, support systems, and mooring lines. Therefore, it is expected that researchers and design engineers worldwide use the model to study, investigate and analyze different aspects of floating offshore wind turbine design, which results is the promotion and advancement of science and technology for floating offshore wind turbines.

Model Order Reduction of Complex Airframes Using Component Mode Synthesis for Dynamic Aeroelasticity Load Analysis

Model Order Reduction of Complex Airframes Using Component Mode Synthesis for Dynamic Aeroelasticity Load Analysis

Simulation and Analysis of Adaptive Power System Type Dynamic Loads

Simulation and Analysis of Adaptive Power System Type Dynamic Loads

Novel development of dynamic behavior of carbon fiber reinforced polymer sandwich panels with stepwise graded adhesive layer

Purpose The purpose of this study is to focus on the developments of carbon fiber reinforced polymer (CFRP) panels with stepwise graded properties on adhesive layer. The various arranges of the graded properties of the adhesive layer have been checked according to experimental results of the literatures and based on applicability. Design/methodology/approach The finite element (FE) models and experimental modal tests of the manufactured CFRP sandwich panel specimens have been investigated. The core thickness, core density and orientation of the fiber direction of the sandwich panel face – sheets have been parametrically checked based on modal behavior. Two fully free and fully clamped boundary conditions (BC) have been checked in stepwise graded adhesive zone (SGAZ) cases and first five non-zero natural frequencies (NF) have been compared. Dynamic response of the SGAZ includes modal analysis and transient dynamic loading have been performed numerically with ABAQUS 6.12 well-known FE code. Findings The first non-zero NF of SGAZ Case 4 was 11.69 per cent higher than homogenous Case 2 and 7.06 per cent lower than Case 1 in fully free boundary conditions. A total of 26.38 per cent is the greatest discrepancy between fist five non-zero NFs of all cases with two BCs (Case 1 vs Case 2 in fully clamped BC). Maximum structural damping behavior and minimum stress picks have been studied during transient dynamic loading analysis of CFRP panel with SGAZ. SGAZ Case 3 (middle adhesive with lower modulus) has increased the maximum structural damping while reducing the minimum out of plain tip displacements during transient dynamic loading by 111.26 per cent in comparison with homogenous Case 2. Also, Case 3 has reduced the Mises stress picks on the adhesive region by 605.68 per cent. Practical implications Making a stepwise graded adhesive region (without any added mass) has been shown that it is a novel and useful way to achieve a wide range of stiffness on CFRP panels. Originality/value Development of the sandwich panels with various stiffness and damping properties.

Time-Dependent Effects of Glaze Ice on the Aerodynamic Characteristics of an Airfoil

The main objective of this study is to estimate the dynamic loads acting over a glaze-iced airfoil. This work studies the performance of unsteady Reynolds-averaged Navier-Stokes (URANS) simulations in predicting the oscillations over an iced airfoil. The structure and size of time-averaged vortices are compared to measurements. Furthermore, the accuracy of a two-equation eddy viscosity turbulence model, the shear stress transport (SST) model, is investigated in the case of the dynamic load analysis over a glaze-iced airfoil. The computational fluid dynamic analysis was conducted to investigate the effect of critical ice accretions on a 0.610 m chord NACA 0011 airfoil. Leading edge glaze ice accretion was simulated with flat plates (spoiler-ice) extending along the span of the blade. Aerodynamic performance coefficients and pressure profiles were calculated and validated for the Reynolds number of 1.83 × 106. Furthermore, turbulent separation bubbles were studied. The numerical results confirm both time-dependent phenomena observed in previous similar measurements: (1) low-frequency mode, with a Strouhal number Sth≈0,013–0.02, and (2) higher frequency mode with a Strouhal number StL≈0,059–0.69. The higher frequency motion has the same characteristics as the shedding mode and the lower frequency motion has the flapping mode characteristics.