Maximum Acceleration Values Research Articles

Experimental and analytical study on sliding vibration of a solid body

It is accepted that the use of base isolation systems within a structure offers a decreased amount of maximum acceleration value throughout the structure and provides a higher level of comfort and safety to the residents even during extremely strong ground motions. We want to propose a new low-cost structural system with the aforementioned benefits of the base isolation. A structural model was developed using an ultra-high-molecular-weight polyethylene film as a friction surface for the whole concrete base of a residential house, creating a friction-based base-isolation system. To understand the friction behavior between the two materials, a computer model was developed in SAP2000 software, and experiments were conducted to confirm the computer model’s proposed behavior. The created computer model is capable of accounting for the adjustments of the dynamic and static friction parameters depending on the velocity of the block. It is possible to conduct the numerical analysis with three-directional input to the system as well as nonlinear solving capabilities. The results of the numerical analysis are compared with the experiment results on a one-directional wave, along with the 1995 Kobe Earthquake ground motion record that had an input in three directions. The results confirm the reproducibility and predictable behavior of the proposed base-isolation method. The maximum acceleration of the concrete base will be no greater than nearly 30% of gravity acceleration regardless of the maximum acceleration of the ground motion.

Study of Objective Assessment Indexes of Shuttle Shift Quality of Wheel Loader

The objective assessment indexes of shuttle shift quality of wheel loader are investigated. The process of shuttle shift is divided into two stages. At the deceleration stage, a large jerk value is observed, and a maximum acceleration value is reached when the shuttle clutch is synchronized. At the acceleration stage, the jerk is too small to be an index of comfortableness. The maximum acceleration, vibration dose value (VDV) and jerk of deceleration stage show a good linear correlation, meaning that the three indexes have similar representative ability for comfortableness assessment. The total duration of shuttle shift is chosen as an index because it is directly related to working efficiency. The duration, in which the torque converter plays a dominant role, is more than 50% of the total duration of shuttle shift, indicating that the duration of shuttle shift is mainly determined by torque converter’s characteristics. The overshoot distance is chosen as the index to represent the dimensional behaviour of the shuttle shift.

ANALYSIS OF DYNAMIC LOADING OF IMPROVED CONSTRUCTION OF A TANK CONTAINER UNDER OPERATIONAL LOAD MODES

An increase in the volume of bulk cargo transportation through international transport corridors necessitates the commissioning of tank containers. Intermodalization of a tank container predetermines its load in various operating conditions depending on the type of vehicle on which it is carried: aviation, sea, air or rail. The analysis of the operating conditions of tank containers, as well as the regulatory documents governing their workload, led to the conclusion that the most dynamic loads acting on the supporting structures during transportation by rail. Namely, during the maneuvering collision of a wagon-platform, on which there are tank containers. In this case, it is stipulated that for a loaded tank container, the dynamic load is assumed to be 4g, and for an empty (for the purpose of checking the reinforcement) – 5g. It is important to note that when the tank container is underfilled with bulk cargo and taking into account movements of fittings relative to fittings, the maximum value of dynamic load can reach significantly larger values. Therefore, in order to ensure the strength of tank containers, an improvement of their structures has been proposed by introducing elastic-viscous bonds into the fittings. To determine the dynamic loading of the tank container, taking into account the improvement measures, mathematical models have been compiled, taking into account the presence of elastic, viscous and elastic-viscous bonds between the fittings, stops and fittings. It is established that the elastic bond does not fully compensate for the dynamic loads acting on the tank container. The results of mathematical modeling of dynamic loading, taking into account the presence of viscous and elastic-viscous coupling in the fittings, made it possible to conclude that the maximum accelerations per tank container do not exceed the normalized values. The determination of the dynamic loading of the tank container is also carried out by computer simulation using the finite element method. The calculation takes place in the software package CosmosWorks. The maximum values of accelerations are obtained, as well as their distribution fields relative to the supporting structure of the tank container. The developed models are verified by the Fisher criterion. The research will contribute to the creation of tank containers with improved technical, operational, as well as environmental characteristics and an increase in the efficiency of the liquid cargo transportation process through international transport corridors.

Identification of landslide potential in Gajahmungkur village Semarang using ground shear strain analysis

The Gajahmungkur village, based on slope and geological structure, are included in the landslide potential category. Research of landslide hazard due to earthquake in weak zone can be done by ground shear strain analysis (GSS). This study aims to provide information related to the potential landslide disaster in the Gajahmungkur village of Semarang city. The data were collected using microseismic method. The research area is 42,000 m2 consisting of 12 points and 3 trajectories. Data processing is done using Software of Geopsy and Surfer to obtain the value of vulnerability index of subsurface ground, maximum ground acceleration value, and ground shear strain value. The result of data analysis shows that the research area at point 9, point 10, and point 12 has the value of vulnerability index which is much higher than the other point so that the value of ground shear strain in all three points is also high. The value of ground shear strain obtained at the order of 10−4 then the dynamic nature that occurs in the research points have a plastic character. This plastic characteristic characterizes the area as a landslide potential.

Durability Determination of the Bearing Structure of an Open Freight Wagon Body Made of Round Pipes during its Transportation on the Railway Ferry

In order to reduce the cost of designing and manufacturing of the new-generation open wagons, it is proposed to construct their carrying systems from round pipes. In order to exploit the proposed designs of wagons in international rail-water communication, it is assumed that they will be equipped with assemblies for fastening of chain binders. The maximal values of accelerations, as components of dynamic load acting on open wagons, made from round pipes during their transportation on a railway ferry, are determined. It is established that when moving the body in the vertical direction for a wagon located on the upper deck, the maximum acceleration value is 0.84g, with angular displacement relative to the transverse axis for the extreme from the anchor point of the wagon body - is 0.1 g, with angular displacement around the longitudinal axis for the extreme from the bulwark of the body of the wagon - is 0.24g. The conducted researches will enable increased efficiency of operation of open wagons through international transport corridors.

Multi-objective optimization design of wheel based on the performance of 13° and 90° impact tests

In order to study the fatigue, 13° impact and 90° impact performance of wheel and propose a wheel structure design and optimization method based on these performance, taking a type wheel as research objects, united topology optimization was performed based on dynamic bending and radial fatigue tests, and an assembled wheel with a magnesium alloy rim and an aluminum alloy disc was designed. Finite element models of the assembled wheel for 13° impact tests were established to analyze the effective plastic strain of the wheel under two conditions of the hammer facing the spoke and the window respectively. And established finite element models of the assembled wheel for 90° impact tests, analyzed the deformation of the inner wheel flange and the effective plastic strain of the rim and disc when the hammer impacted facing the window, and analyzed the failure range of the wheel and the effective plastic strain of the rim and disc beyond the 25% circumferential range (90°) of the impact position when the hammer impacted facing the valve window. Then studied the relationship between these performance and the wheel structure. The parametric models of the assembled wheel under four finite element conditions were established with 12 design variables defined by using the mesh morphing technology. The Optimal Latin Hypercube design and Hammersley design were used to fit the Kriging surrogate model and to validate the precision of the surrogate model in Isight software platform where the DEP-MeshWorks and LS-DYNA software were integrated. Using the established surrogate model, Non-dominated Sorting Genetic Algorithm-II (NSGA-II) was adopted to perform the multi-objective optimization of the wheel. The Pareto frontier was obtained, and a compromise solution was selected as the optimal design result. The weight of the optimized assembled wheel was 28.59% less than that of the same type cast aluminum alloy wheel. Test the optimized wheels referencing four finite element conditions, and validate the correctness of finite element models by comparing the simulation and test values of equivalent strain and maximum acceleration on measuring points. The simulation analyses were in agreement with the test results. A wheel structural design process and multi-objective optimization method based on the fatigue, 13° impact and 90° impact tests performance were realized in this article, providing the theoretical and technical basis for wheel optimization design.

Source mechanisms and simulation of ground motions of 18 and 22 July 2014 Suez earthquakes

ABSTRACTOn 18th and 22nd of July, 2014, two felt earthquakes have occurred in the northeastern part of Egypt (Cairo-Suez District) near Suez city with magnitude ML = 4.3 and ML = 4.0 respectively. The datasets used involves the two earthquakes recorded by Egyptian National Seismic Network (ENSN) and regional seismic stations (Jordan and Cyprus) to obtain the focal mechanism. A stochastic method is used to obtain high-frequency ground motion synthetics based on local site effect using 5 sites ambient noise (Microtremor) measurements to obtain the resonance frequency of the sediments. The ground motion parameters of (PGA), (PGV), (PGD) and spectral accelerations (SA) of the two earthquakes are obtained. The results show that the maximum value of the peak ground acceleration is observed at the site no. 1 (Northwest the apex of the Suez Gulf) due to near source-site distance and local site conditions (H/V = 4.4), while the minimum value is observed at the site no. 5 (Southwest of the small Bitter Lake) due to a large distance from the source (H/V = 2.10). The damped pseudo-acceleration was applied for the simulation at damping (0.5%, 1%, 5%, 10% and 20%). These results indicated, the efficiency and the importance of the local site conditions on strong ground motions.

Fluid-Structure Interaction Vibration Response Analysis of the Hydrocyclone Under Periodic Excitation

Considering that the hydrocyclone will be affected by internal and external fluid forces in practical work, the numerical simulation method of fluid-structure interaction(FSI) of the hydrocyclone is proposed, and the finite volume method is used in the fluid domain and the finite element method is used in the solid domain. According to the numerical simulation of the flow around a circular cylinder, the magnitude and frequency of fluid flow around the hydrocyclone are obtained. On this basis, the numerical simulation and experimental research of the hydrocyclone are carried out, and the vibration characteristic of the hydrocyclone under the FSI condition is discussed, which the modal frequencies and modes of the hydrocyclone, the structural displacement and stress distribution characteristics of the FSI interface under periodic excitation are obtained. The results of numerical simulation and measured are compared and analyzed. The distribution trend and position of the maximum acceleration values are in good agreement between the measured and numerical simulation. The maximum deformation and the maximum acceleration values position of the hydrocyclone structure which is near the intersection between small conical section and tail pipe, and the structural deformation and maximum acceleration values of the hydrocyclone increase with the increase of inlet velocity. The analysis shows that the FSI model of the hydrocyclone is reasonable. Moreover, the influencing factors of fluid flow around the hydrocyclone should be considered in the future design and application of the hydrocyclone.

Impact of sensor/reference position on player tracking variables: Center of scapulae vs center of pelvis

Electronic performance and tracking systems (EPTS) traditionally rely on one of two body positions as the ultimate representative for the entire body in space: the upper torso between the scapulae (GPS- and radar-based systems) or the body’s estimated center (optical and some radar-based systems). The aim of this study was to quantify the impact of the respective reference point upon the resulting kinematic tracking variables. We present a marker-based method comparing center of pelvis (COP) derived tracking variables with center of scapulae (COS) derived tracking variables in a 30 × 30 m (900 m2) VICON measurement area. Fourteen male soccer players completed a running circuit with prescribed team-sport specific movements. Results showed that differences between COP and COS heavily depend on the underlying movement characteristic. Low-speed running showed the lowest deviations whereas accelerated movements and movements with sharp changes in direction lead to a significant increase in the observed differences. Results further showed that COS sprinting distance was on average −44.65% (p < 0.001) lower in comparison to COP. Similarly, maximum speed obtained from COS was −2.94% (p = 0.001) lower in comparison to COP. On the contrary, maximum acceleration values of COS were on average 16.15% (p = 0.02) higher compared to COP. Our work illustrates that the anatomical reference point used to represent the entire body in space needs to be carefully considered in the interpretation of tracking variables delivered by different EPTS.

Response Spectra of Structures under Subway Induced Vibrations

Passing underground trains induce vibrations transmitted to the ground surface and the nearby structures. Ordinarily, these vibrations do not result in structural damage but can harm nonstructural elements and disturb the occupants. These effects are more pronounced when evaluating buildings like hospitals, laboratories, museums, etc., and their assessment is an important design need. To respond to this requirement, in this paper response spectra for passing trains moving with different velocities are calculated. Using these spectra, without resorting to the time consuming and costly analysis of a tunnel-soil system under moving loads, the maximum structural responses can be calculated rapidly. To make this end, the soil-tunnel interaction is modeled using a three dimensional (3D) finite difference scheme under the standard moving train loads. The dynamic analysis of such a system results in the ground surface vibration time histories at different distances from the tunnel axis. Then the maximum values of acceleration, velocity, and displacement responses are calculated for a single degree of freedom (SDOF) dynamical system. The above calculations are accomplished for different standard trains, train velocities, tunnel depths, distances from tunnel, and soil types, and are presented as response acceleration, velocity, and displacement spectra.

Improved trajectory planning of an industrial parallel mechanism by a composite polynomial consisting of Bézier curves and cubic polynomials

A new composite polynomial is generated, to be used in the trajectory planning of a 2-dof parallel mechanism; by combining cubic polynomials with Bézier curves based on quadratic Bernstein polynomials. By the cubic polynomials, a smooth trajectory is obtained in the vicinity of the starting and ending points, while a better convergence is obtained to the via points by the Bézier curves. The position, velocity, and acceleration profiles obtained using this new polynomial are compared with those obtained using the cubic polynomial spline method. The position, velocity, and acceleration profiles achieved by the new polynomial are smoother; and more, maximum speed and acceleration values are lower than those obtained by the cubic spline method. Due to these lower values, lower capacity actuators may be utilized and the life of the actuators may be extended. On the other hand, the continuous acceleration curve of the composite polynomial will prove less jerky motion, which means less vibration. It is also possible to indicate energy saving potential when considering the speed-torque characteristic curves of servomotors. Finally, a working prototype is manufactured and real-time experiments are carried out to demonstrate the validity and competency of the proposed composite polynomial approach.

Effect of plus sizing on driving comfort and safety of users

This paper contains the results of a track test into the performance of tires manufactured by a leading brand applied on a surface with different conditions (dry and decreased friction). The research applied new tires in a common size (185/65R14), half-worn tires with the same size and replacement tires size 205/45R16. The tires were subjected to experiments involving stopping distance, average speed as well as maximum values of acceleration and deceleration.

Analisis Pengaruh Getaran Peledakan Terhadap Kestabilan Lereng Pada Tambang Batubara Pit Roto Selatan Site Kideco, Kecamatan Batu Sopang, Kabupaten Paser, Provinsi Kalimantan Timur

In PT. BUMA site, there are some landslide which affected by blasting activity. Blasting activity iscarried out to destroy overburden material. The purpose of this research is to know the type oflandslide, the coefficient value of vibration decay from Peak Particle Acceleration (PPA), rock masscondition constant value from Peak Particle Acceleration (PPA), the Peak Particle Acceleration (PPA)value and the maximum acceleration (amax) which is at a point of safe in South Roto Pit. The researchmethods which used are the window mapping method in several sections at South Roto Pit.Description of rock mass that includes type of rock, rock strength, degree of weathering, block shape,type and shape of discontinuity, discontinuity filler and roughness level of discontinuity. ThisDescription of rock mass use Geological Strength Index (GSI) classification as a parameter to knowthe mechanical properties of rock mass (cohesion and internal shear angle). The research area has atype of toppling failure with eastward avalanche. The value of coefficient of vibration decay from PPA(k) is 44,66. The rock mass condition constant (α) is 1,802. The safe value of PPA highwall slopesarea of B STA 1 value is 0,184 g and the maximum acceleration (amax) value is 0,12 g. Highwall slopesarea B STA 2 with PPA value is 0,0769 g and maximum acceleration (amax) value is 0,05 g. Highwallslopes area C5 STA 3 with PPA value is 0,153 g and the maximum acceleration (amax) value is 0,1 g.Highwall slopes area C5 STA 4 with PPA value is 0,0307 g and the maximum acceleration (amax) valueis 0,02 g. Overall slopes area with PPA value is 0,0307 g and maximum acceleration (amax) value is0,02 g.

Method for Determining the Ultimate Strain for Rocks of the Earth’s Crust from the Magnitude of Relative Slips on the Earth’s Surface after a Strong Earthquake

The ultimate strain value for rocks in aggregate with their other physicomechanical characteristics plays a substantial role when solving different problems related to the bearing capacity and behavior of soils. These include determination of the maximum displacement, velocity, and acceleration values of soils during earthquakes and estimation of the potential strain energy accumulated in a medium during strong earthquake preparation. The latter parameter is also key in predicting earthquakes from the ultimate strain of rocks. The paper describes a technique developed by the author for determining the ultimate strain of soil columns under natural conditions from their relative slope on the surface after a strong earthquake. The empirical dependences of the ultimate strain of rocks on earthquake magnitude, relative slip, rupture length, and the seismic moment are obtained by analyzing their values calculated by the proposed method for 44 strong earthquakes with magnitudes of 5.6–8.5. A comparative analysis of the ultimate strain values obtained by other researchers by geodesic triangulation is performed.

Inertial sensing of the motion speed effect on the sit-to-walk activity

The STW execution at motion speed faster than normal most possibly enhances the risk for balance loss due to the increase in body segment accelerations. The purpose of the study was to use inertial sensing to examine the effect of motion speed on the STW segmental kinematics and its temporal events. Eighteen young men (20.7 ± 2.0 years) performed STW trials at preferred (PS) and fast (FS) motion speed. Data were collected with Xsens inertial sensors positioned at the trunk, thigh, shank, and foot segments. The maximum segmental values of angular displacement, angular velocity and linear acceleration, the duration of total STW (ttotal), the absolute and relative (% ttotal) phase duration (Flexion, Transition, Extension, Walking) and, the absolute and relative time taken to reach each maximum value were determined. In FS, ttotal and the absolute phase duration (except for Transition), were all significantly shorter (p = 0.000). The relative phase duration was not altered (p > 0.05), except for the Extension shortening (p = 0.001). The maximum angular displacement was altered only for the thigh (decreased, p = 0.038) and shank (increased, p = 0.004). Maximum angular velocities and linear accelerations were all significantly increased (p = 0.000 for all). The absolute time to reach the maximum values shortened in FS (p ≤ 0.05), while, the relative times were not altered (p > 0.05), except for the delayed trunk maximum angular displacement (p = 0.039). Inertial sensing appears to identify the motion speed effect on STW segmental kinematics and their temporal events in healthy young men. The results of the study may contribute improving the preventive or rehabilitation interventions in persons with impaired postural control.

Predicting of the Seismogram and Accelerogram of Strong Motions of the Soil for an Earthquake Model Considered as an Instantaneous Rupture of the Earth’s Surface

Problems of the prediction of displacement and acceleration values for strong soil displacements are considered for the case where an earthquake is regarded as an instantaneous mechanical rupture of the Earth’s surface. We have attempted to develop, based on recent concepts of earthquake generation process, simplified theoretical methods for the quantitative prediction of soil displacement parameters during strong earthquakes. As an illustrative example, we consider an earthquake originating as a consequence of relative displacements of suddenly ruptured blocks in a horizontal direction with a given initial velocity. An empirical relationship between soil particle motion velocity near the rupture and at a certain distance from it, on one hand, and the earthquake magnitude, on the other hand, was established. It is assumed that the impact of inertial motions of a deep soil stratum on the inertial motions of upper subsurface soil stratum at instantaneous break of a medium can be neglected. By solving a wave problem for a multilayer near surface stratum, analytical relations were developed for a soil seismogram and accelerogram on the surface depending on the physical–mechanical and dynamic characteristics of the soil at all layers of the stratum; attenuation coefficients of mechanical soil vibrations; the distance to the rupture; and the magnitude of the predicted earthquake. The results obtained enable us to determine the maximum displacement and acceleration values of the soil, taking into account local soil conditions and their variations over time, as well as the values of the predominant vibration periods in the soil. The method was applied for solid and loose soil basements.

Mechanical Forces Experienced by Simulated Patients Evacuated During Dismounted Military Movement in Mountainous Terrain.

Given a denied or resource-limited area of operations, when air medical evacuation would require extended delay, should dismounted movement through difficult terrain dissuade an attempt of immediate ground evacuation? Understanding the magnitude of external forces during dismounted movement would inform planning in such circumstances. We assessed the mechanical impact experienced during dismounted evacuation from mountainous terrain. We also describe a protocol using a portable accelerometer to evaluate evacuation. A triaxial accelerometer and a semiflexible litter were used to collect data during the Army Mountain Warfare School Rough Terrain Evacuation Course. We used the generalized extreme value (GEV) distribution, using maximum likelihood estimation, to model maximum acceleration values. It was determined that the accelerometer should be mounted directly onto a mannequin when using semiflexible litters. GEV analysis from a mannequin-mounted trial revealed that for 1-minute evacuation intervals, 10% would have a maximum acceleration over a value between 2.4g and 3.7g. This interval encompasses the maximum acceleration from evacuation using a Mine-Resistant Ambush Protected (MRAP) vehicle, measured by the US Army Aeromedical Research Laboratory. The peak acceleration from a 75-minute, mannequin-mounted trial was 5.5g, approximately twice as large as the MRAP maximum. For the evacuee, the acceleration experienced during dismounted evacuation in mountainous terrain can be comparable to MRAP evacuation, especially with sufficient planning that avoids points of maximum impact. Leaders can consider this comparison during planning.

Location on the Body of a Wearable Accelerometer Affects Accuracy of Data for Identifying Equine Gaits

Monitoring horse activity is a valuable aid for horse caretakers to provide recommendations to improve equine health. One method for monitoring equine activity is through the use of an accelerometer to determine exercise intensity. A three-axis accelerometer was installed at three locations on the equine to determine activity measurement accuracy for the walk, trot, and canter. The objectives were to determine which location results in the most accurate step count, threshold acceleration values for each gait, and correlations between the thresholds and horse characteristics. The accelerometer output was compared to step count as determined from video recordings. Threshold values to delineate between gaits were determined by the maximum and minimum acceleration values observed during each gait for all equines. The average frequency was identified for each gait, and distinct ranges were determined. The results revealed a significant difference (P = .02, α ≤ 0.05) between all three sensor locations and the video analysis. There was a strong, positive linear correlation between the number of steps from the accelerometer and video analysis (r = 0.926, P < .001). The front leg location had the highest correlation r = 0.963 (P < .001). While all sensors underestimated the step count, there was not a significant difference between the accelerometer on the front leg and the video analysis at the walk. The height of the equine significantly interacted with step frequency for the canter. An equine activity monitor using an accelerometer yields more accurate step counts when placed on the front leg of the horse, though horse height needs to be considered for the canter.

Evidences of a tectonic uplift and seismic hazard in south of the Pie de Palo Range, San Juan-Argentina

ABSTRACTIn the Central Andean region of Argentina, we found gravimetric and geomorphological evidence of an uplifting of the crystalline basement of Pie de Palo range. Within this zone, we observed a positive gravimetric anomaly in the extreme South of Pie de Palo, extending towards the South of Pampean ranges. By means of the geophysical technics, it was possible to determine the magnitude and geometrical form of the anomalous body. The evidence of a tectonic uplifting is also clearly manifested in the LandSat images, by observing the displacement of the course of the San Juan River towards the South. The study region is one of the major cortical and lithospheric regions with seismic activity in the country, where three of the most devastating earthquakes occurred over the last 73 years. The results would indicate that this region will continue to be one of the major seismically generating potential, significantly implying seismic dangers. The seismic risk studies indicate that the greatest hazard zone is found between the Pre-Cordillera and the Pie de Palo Range. The highest maximum acceleration values (PGA) are 242, 393, and 543 gal for return periods of 72, 475, and 2475 years, respectively.

Seismic Hazard Assessment for the protection of Cultural Heritage in Greece: Methodological approaches for National and Local Scale assessment (pilot areas of Aighio, Kalamata and Heraklion)

The rich Greek cultural heritage has been always threatened by the intense seismic activity in the broader Aegean region. Τhe objective of the presented project is to develop an integrated tool for the engineers in order to protect the Greek monuments, museums and archaeological sites against strong earthquakes. In order to achieve this goal a GIS-based database was developed with a bidirectional purpose: to collect and combine all necessary data about the monuments and their regional geological and seismotectonic conditions and to assess seismic hazard for each and every monument using the most modern techniques. In this paper we present the structure and development of our database, we propose a methodological procedure for estimating seismic hazard in Greece which will be the basis for the structural assessment of historical structures. The preliminary results show that the estimated values of maximum ground acceleration, in several areas nearby large faults exceed those proposed by the earthquake protection code of Greece by a significant amount. Therefore an update of the protection code would be necessary. Subsequently the estimated values of maximum ground acceleration have been applied to three cases of monuments for the determination of the most vulnerable parts of the structure and the verification of the observed pathology.