Value Of Rotation Angle Research Articles

Study on Grain Boundary Mechanical Behaviors of Polycrystalline γ-TiAl Using Molecular Dynamics Simulations

In this study, the molecular dynamics (MD) method was used to study the tensile deformation of polycrystalline γ-TiAl with complex and random grain orientations. Firstly, the tensile deformation was simulated with different average grain sizes (8.60 nm, 6.18 nm, and 4.50 nm) and strain rates (1 × 108 s−1, 5 × 108 s−1, and 1 × 109 s−1). The results show that the peak stress increases with an increase in tensile strain rate, and the peak stress decreases as the grain size decreases, showing an inverse Hall–Petch effect. Upon observing atomic configuration evolution during tensile deformation, it is found that the grain boundary is seriously distorted, which indicates obvious grain boundary sliding occurring. With a further increase in the loading, some dislocations nucleate at the grain boundaries and propagate towards the interior of the grains along the grain boundaries, which demonstrates that dislocation motion is the primary coordination of the mechanical process of the grain boundaries. The dislocation density near the grain boundaries continues to increase, leading to the generation of micro-cracks and eventually causing material failure. Another interesting phenomenon is that the grains rotate, and the specific rotation angle values of each grain are quantitatively calculated. Grain rotation relaxes the stress concentration near the grain boundaries and plays a toughening role. Consequently, the plastic deformation behaviors of polycrystalline γ-TiAl are achieved through the grain boundary mechanical process, that is, grain boundary sliding and grain rotation.

Design and development of a wrist rehabilitation device with an interactive game

In this paper, a wrist rehabilitation device integrated with an interactive game is developed. The device is designed for flexion/extension and ulnar/radial motions. The motion of the wrist joint is measured by an optical encoder. A hall sensor is also used to measure the force emitted from the DC motor. These data are fed back to the interactive gaming environment to create the movement of goals in the video game. There are two types of interactive games designed. The first requires the practitioner to move their wrist to achieve a specific goal. The second exercise requires the practitioner to move their wrist joint continuously to reach moving targets. In the game interface, therapists can easily adjust training intensity, training time, and change training limits depending on the recovery status of the patients. At the same time, it also records the patient's training efforts and monitors visual graphs of performance during exercise. The experiments were conducted to tune the games and to get a preliminary evaluation of the device. The feedback from the patients and therapists are recorded to improve the device and game interfaces. Game parameters are adjusted during the patient's exercise process under the supervision of a physiotherapist. The values of rotation angle and torque are collected and then presented in graphs so that physiotherapists can assess the patient's recovery status. The results show that the patients enjoy the games. The therapist is satisfied with the game interface and says that the games are intuitive and easy to play.

Mechanical characterization and torsional buckling of pediatric cardiovascular materials

In complex cardiovascular surgical reconstructions, conduit materials that avoid possible large-scale structural deformations should be considered. A fundamental mode of mechanical complication is torsional buckling which occurs at the anastomosis site due to the mechanical instability, leading surgical conduit/patch surface deformation. The objective of this study is to investigate the torsional buckling behavior of commonly used materials and to develop a practical method for estimating the critical buckling rotation angle under physiological intramural vessel pressures. For this task, mechanical tests of four clinically approved materials, expanded polytetrafluoroethylene (ePTFE), Dacron, porcine and bovine pericardia, commonly used in pediatric cardiovascular surgeries, are conducted (n = 6). Torsional buckling initiation tests with n = 4 for the baseline case (L = 7.5 cm) and n = 3 for the validation of ePTFE (L = 15 cm) and Dacron (L = 15 cm and L = 25 cm) for each are also conducted at low venous pressures. A practical predictive formulation for the buckling potential is proposed using experimental observations and available theory. The relationship between the critical buckling rotation angle and the lumen pressure is determined by balancing the circumferential component of the compressive principal stress with the shear stress generated by the modified critical buckling torque, where the modified critical buckling torque depends linearly on the lumen pressure. While the proposed technique successfully predicted the critical rotation angle values lying within two standard deviations of the mean in the baseline case for all four materials at all lumen pressures, it could reliably predict the critical buckling rotation angles for ePTFE and Dacron samples of length 15 cm with maximum relative errors of 31% and 38%, respectively, in the validation phase. However, the validation of the performance of the technique demonstrated lower accuracy for Dacron samples of length 25 cm at higher pressure levels of 12 mmHg and 15 mmHg. Applicable to all surgical materials, this formulation enables surgeons to assess the torsional buckling potential of vascular conduits noninvasively. Bovine pericardium has been found to exhibit the highest stability, while Dacron (the lowest) and porcine pericardium have been identified as the least stable with the (unitless) torsional buckling resistance constants, 43,800, 12,300 and 14,000, respectively. There was no significant difference between ePTFE and Dacron, and between porcine and bovine pericardia. However, both porcine and bovine pericardia were found to be statistically different from ePTFE and Dacron individually (p < 0.0001). ePTFE exhibited highly nonlinear behavior across the entire strain range [0, 0.1] (or 10% elongation). The significant differences among the surgical materials reported here require special care in conduit construction and anastomosis design.

Effects of Wearable Lumbar Support Exoskeleton on Motion of Torso and Dynamic Plantar Pressure in Single-Shoulder Load.

Work-related musculoskeletal disorders are a major health issue, but there is little research to show whether active lumbar exoskeletons are suitable for single-shoulder load. The purpose of this study was to identify the effect of wearable lumbar support exoskeleton with single-shoulder load on movement of the lumbar and thoracic spine and plantar pressure. The experiment was conducted considering ten healthy male young adults. Data about three-dimensional motion angles of the lumbar and thoracic spine, as well as plantar pressure, were collected in the control condition (0% of body weight: 0% BW), experimental condition A (single-shoulder load: 5% BW and 10% BW), and experimental condition B (single-shoulder load and left lateral traction: 5% BW-T and 10% BW-T). The two-way repeated measures analysis of variance (ANOVA) was conducted with device and weight as within subject factors. The level of statistical significance was set at p<0.05. In experimental condition A, significant difference observed in the lumbar and thoracic flexion angle compared to 0% BW (all p<0.05). the plantar pressure information was affected by the single-shoulder load especially about plantar pressure. In experimental condition B, there were no significant differences on the all values of lumbar and thoracic angles other than the ROM value of thoracic rotation angle in 5% BW-T and 10% BW-T (p = 0.0082 and p = 0.0056). Furthermore, the COP of the subject was symmetrical in experimental condition B, the peak force increased compared to 0% BW but less than the single-shoulder load. The WLSE provided a possibility for protecting and preventing the human lumbar and thorax in single-shoulder load.

A Stress Measurement Method for Steel Strands Based on Spatially Self-Magnetic Flux Leakage Field

Metal Magnetic Memory (MMM) exhibits the advantage of not requiring embedded sensors or external excitation, making it suitable for inspecting ferromagnetic components in engineering structures. This study introduced MMM into stress detection of steel strands. Graded tensile tests were conducted on the steel strands to investigate the correlation between Self-Magnetic Flux Leakage (SMFL) signals and stress levels. Different spatial detection positions with varying Lift-Off Values (LOV) and Rotation Angle Values (RAV) were set to examine the distribution of spatial SMFL field under load. Furthermore, a magnetic characteristic parameter AN was proposed to assess the stress level of the steel strands. The results indicate that the rate of change in the middle region of the SMFL curve was lower than that at the beginning and the end. Additionally, with increased applied load, the SMFL curve exhibited systematic variations, and the dispersion of the normal component curve gradually decreased. By utilizing the magnetic characteristic parameter AN, the stress in the steel strands can be calculated, with the parameters determined based on LOV and RAV. This achievement expanded the nondestructive testing methods for steel strands and holds significant research value.

Range of Motion Measurements of the Hip Joint Are Useful in Screening for Acetabular Dysplasia in Healthy Young Japanese Women.

The purpose of this study is to clarify whether a hip range of motion (ROM) measurement is useful in screening for early hip osteoarthritis with acetabular dysplasia (AD). Subjects were 58 healthy Japanese women volunteers (21.1 ± 0.7 (20 - 22)). We evaluated a total of 116 hip joints in these 58 cases. Sharp angle and centeredge angle were 44.1° ± 3.1° (37.0° - 51.5°) and 30.7°± 6.2° (19.5° - 47.0°), respectively. AD was present in 47.4%, but there were no severe cases. First, we compared the ROM of the hip joints with AD (AD group) and without AD (control group) according to the Mann-Whitney U test. Extension angles and external rotation angles in the AD group were significantly smaller than in the control group (18.9°± 6.1° VS. 22.1°± 4.2°, p= 0.01636, 26.3°± 8.9° VS. 34.1°± 8.8°, p= 0.001362, respectively). Next, we evaluated the following factors associated with AD by logistic regression analysis after adjustment for age: flexion, extension and internal and external rotation angles of the hip joint. As a result, internal rotation and external rotation were extracted as related factors. The area under the ROC curve was determined to have a moderate accuracy (0.72996). Cut off values of internal rotation and external rotation angles were 50 degrees and 35 degrees, respectively. Our findings suggest that ROM measurement of the internal and external rotation angles would be useful as a screening for AD in healthy young Japanese women without symptoms.

Curve-on-curve technique does not improve tibial coverage in total knee arthroplasty in comparison to tibial tuberosity technique with use of anatomical implants: randomized controlled trial

IntroductionDuring the last years, main attention while performing total knee replacement was paid to femoral component alignment; however, there is still lack of studies concerning tibial baseplate rotational alignment, especially in terms of anatomical designs of knee prosthesis. Some recent studies proved that tibial baseplate malrotation might be a cause of knee pain and patients’ dissatisfaction. The aim of this study was to compare tibial component rotation and its coverage on the tibial plateau achieved with curve-on-curve and tibial tuberosity techniques (t-t technique) with use of anatomic knee designs with asymmetric tibial baseplate.Materials and methodsA total of 88 patients were randomly assigned in a 1:1 ratio to undergo total knee arthroplasty with use of the PERSONA PS (Zimmer Biomet) knee design with an asymmetric baseplate. The rotation of the tibial component was assessed and performed with two different techniques: curve-on-curve technique and tibial tuberosity technique. Tibial component rotation was measured on computed tomography (CT) scans using the method suggested by Benazzo et al. and designed for asymmetrical implants. For the measurement of the tibial bone coverage, the component surface area was outlined and measured on a proper CT section, then the tibial cut surface area was outlined and measured on a section just below the cement level. Pre- and post-operative range of motion was measured by another independent researcher 12 months post-operatively during follow-up visit.ResultsThere was a statistically significant difference between both groups in median value of tibial rotation angle: 7° (interquartile range (IQR) = 0–12) in curve-on-curve technique group vs 2° (IQR-1–7) in tibial tuberosity technique group, probability value (p) = 0.0041, with values above 0 meaning external rotation of the component. There was no statistically significant difference between both groups in terms of range of motion (ROM) with average values of 124.3° ± 13.0° for curve-on-curve technique and 125.6° ± 12.8° for t-t technique with p = 0.45. There was a statistically insignificant difference between both groups in terms of coverage percentage in slight favor for curve-on-curve technique (85.9 ± 4.2 vs 84.5 ± 4.8, p = 0.17).ConclusionIn this study, no difference between the groups in terms of tibial bone coverage and range of motion was proved, even though both techniques differed significantly with values of tibial rotation. Future studies should be focused on influence of specific values of tibial rotation on patient-reported outcomes and survivorship of anatomic knee implants.

Анализ технологической и кинематической возможностей формообразования упорной резьбы фрезой общего положения

The paper proposes new kinematic methods in shaping external and internal buttress thread by milling with a single-disk tool according to the scheme with crossing axes of the thread and the general position tool using two angles of its rotation. The range of the thrust threads standard sizes was established, which implied technological possibility of milling using the proposed kinematic methods with one tool standard size. Accuracy of the buttress thread according to GOST 10177-82 was studied on the basis of geometric simulation of shaping kinematics, and values of the maximum geometric error and the error in the average diameter were determined depending on the tool rotation angles and geometric parameters. For the accepted standard sizes of the buttress threads, values of rotation angles of the thread cutter rotation axis and parameters of its working part were found, which makes it possible to shape the thread with a degree of accuracy corresponding to GOST 25096–82.

Indirect measurement of solar array rotation angle for satellite emergency rescue

In the emergency rescue mission, the primary task is to achieve the satellite’s orientation to the sun and ensure the energy supply. For this purpose, it is necessary to determine the rotation angle of solar array relative to satellite body. However, the rotation angle cannot be measured directly by the angle sensor in case of satellite emergency. To handle this issue, an indirect measurement method of solar array rotation angle is proposed in this paper. First, the indirect point measurement value of solar array rotation angle is given via the relationship between satellite body coordinate frame and solar array coordinate frame and the Rodrigues’ rotation formula. Then, the interval analysis technique is used to determine the upper and lower bounds of rotation angle and evaluate the influence of measurement noises. Based on the determined point measurement value and the interval analysis results, a zonotopic Kalman filter-based strategy is further proposed to improve the measurement accuracy. Finally, the effectiveness and validity of the proposed approach are demonstrated by numerical simulations, which illustrate its engineering application value.

A multi-objective optimization design of industrial robot arms

This paper introduces a multi-objective design mechanism to minimize both the initial and running costs of industrial robot arms. The goal of the design problem is to decide the type of material and physical dimensions of the robot arm to withstand high loads at vulnerable locations using stress analysis. Additionally, it selects the material architecture for the robot links based on a vibration analysis to avoid robot failure at or close to the resonance frequency. Hence, a set of design equations based on stress analysis are developed using analytical approaches while the findings are supported by finite element simulations in ANSYS. These decide the type of material, cross-section area, factor of safety (FoS), and maximum deflection of the robot links in terms of the mass-loads. Moreover, the vibration analysis is conducted to enhance the dynamic characteristics of the robot arm. Therefore, the excitation frequency is modified by changing the mass and the robot segment-material to evade working at the natural frequency. Modal analysis is conducted using ANSYS to identify the fundamental frequencies and their modal shapes. Then, a material selection mechanism based on finite element analysis is considered to allow a safe frequency operation range for the robot arm. A customized robot arm structure that combines Magnesium and Aluminum alloy with highly improved FoS and minimizes the initial and operating costs is proposed. In addition to the body structure of the robot arm, the influence of the reducers and motors on the stiffness and vibration of the robot arm is presented. Finally, the motion of the robot arm is optimized using a Genetic Algorithm subject to a set of boundary conditions imposed by the desired mission. The effect of rotation angle value in the power consumption is presented. The coefficients of a developed angular displacement function are optimized to ensure minimum power consumption during the robot missions.

Melting enhancement of PCM in a finned tube latent heat thermal energy storage

The current paper discusses the numerical simulation results of the NePCM melting process inside an annulus thermal storage system. The TES system consists of a wavy shell wall and a cylindrical tube equipped with three fins. The enthalpy-porosity method was utilized to address the transient behavior of the melting process, while the Galerkin FE technique was used to solve the system governing equations. The results were displayed for different inner tube positions (right-left–up and down), inner cylinder rotation angle (0 ≤ α ≤ 3π/2), and the nano-additives concentration (0 ≤ ϕ ≤ 0.04). The findings indicated that high values of nano-additives concentration (0.4), bigger values of tube rotation angle (3π/2), and location of the tube at the lower position accelerated the NePCM melting process.

Analysis of Posture Parameters in Patients with Idiopathic Scoliosis with the Use of 3D Ultrasound Diagnostics-Preliminary Results.

(1) Background: Idiopathic scoliosis occurs in 2 to 4% of children between 10 and 16 years of age. Due to the harmfulness of radiological examination, non-invasive devices, including the 3D ultrasound technology and Scolioscan apparatus, are more and more frequently used for postural diagnostics. The aim of the study was to analyze the parameters of posture in patients with idiopathic scoliosis with the use of 3D ultrasound diagnostics. (2) Methods: The study included 20 girls, aged 10 to 16 years, with double-curve idiopathic scoliosis (the value of primary curve ranged from 25–50°), types I and II according to King–Moe classification. On the basis of X-ray scan, the Cobb angle of primary and secondary curves was assessed, the skeletal maturity was evaluated with the Risser test, and the type of scoliosis was determined. The girls participated in a 3-week rehabilitation program. The examinations were performed before and after therapy. A scoliometer was used for measurements. Each of the participants underwent individual therapy. The three-plane approach to asymmetric exercises was based largely on positions that included primary curve correction with hypercorrection of the secondary curve. (3) Results: After the therapy, values of trunk rotation angles and the angle of scoliotic curvature of secondary curve were significantly lower than before the therapy, except for the value of the primary curve angle. The parameters measured by X-ray were significantly and positively related to the results obtained with the scoliometer and the scolioscan. (4) Conclusions: The application of therapy that takes into account summing parameters may prevent the deterioration of the secondary curve when treating patients with idiopathic scoliosis. The observed correlations between the parameters of the radiological examination, the scoliometer, and the scolioscan prove the possibility of their interchangeable application in the assessment of effects of the therapy. Three-dimensional ultrasound diagnostics may become an alternative to radiological examination in assessing the treatment effects of patients with idiopathic scoliosis.

SmartRock-Based Research on Gyratory Locking Point for Stone Mastic Asphalt Mixture

For gyratory compaction, the concept of the locking point was initially developed to identify the compactability of asphalt mixes and to alleviate potential aggregate crushing in the mold. Most previous studies on the locking point were based on specimens’ height change. Recent studies have indicated that the gyratory locking point of cold mix asphalt mixtures could be determined by the rotation angle range indicator using SmartRock. However, height or rotation angle change ultimately reflects a change in volume. Additionally, there is no clear physical and mechanical connection between the volume change and the gyratory locking point. In this paper, a stone mastic asphalt mixture (SMA 13) was selected for gyratory compaction applying various compaction temperatures. The compaction data were recorded by a SmartRock embedded in different positions. Collected data included stress, rotation angle, and acceleration. The major findings are as follows: (1) the specimen’s locking point could be determined based on a representative stress value when the SmartRock was embedded in the specimen’s center, and the results are close to the traditional evaluation results (LP3 or LP2-2-3); (2) the representative rotation angle value reached a plateau earlier than the representative stress value; (3) the representative acceleration value is not suitable for characterizing the interlocking process during gyratory compaction.

Structure integrity evaluation of gas protective wall for new construction method using strength test and numerical analysis

Gas protective walls are safety elements that can withstand the pressure of fires or explosions caused by gas leaks, thus preventing the spread of explosion damage to other facilities or operators. However, in the new construction or expansion of gas facility rooms in existing buildings, the barrier must often be built even if it does not satisfy the legal standards regarding the accepted construction methods. In these cases, the gas barrier for the existing building should be constructed by the new construction method using chemical anchor bolts. However, no performance evaluation data or reliable engineering verification results are available for the entire gas facility room based on actual experiments. In this study, based on a review of regulations on gas barriers, the protective performances of the new barriers were compared in terms of displacement, rotation angle, rebar strain, and yield value of the concrete surface through actual strength demonstration experiments. Based on these results, the protection performance of an entire gas facility room that could not be constructed and tested in real time was evaluated by a fluid structure interaction (FSI) analysis using the TNT(Trinitrotoluene) equivalency method and three-dimensional AUTODYN.

Applying Simulink to solve the differential equation of rotational angle of a vibrating building resting on a viscous foundation

Dynamic effects on structures are complicated topics, both in theoretical and experimental aspects. This article aims to study more deeply the effects of the waves on the response of a receiver footing in the vicinity. This paper establishes the governing equation for the vibrating structure resting on a viscous soil foundation. By prescribing all the rotating motions happened to the footings, including the sliding moments, and the anti-sliding moments, a differential equation is established. The viscous characteristics that based on a laboratory test-based results is considered, and the dynamic equilibrium equation of all the moments is manipulated to an ordinary diffferential equation. Beside the analytical solution, solved by the conventional approach, a Matlab Simulink diagram is created to solve the equation. The result indicates there is a value of rotational angle at which the rocking structure would attain during the process of vibration in long enough time. This solution could explain the failure mode of buildings which are constructed nearby a road, are stirred and vibrated under the dynamic effects caused by traffic mobility. These dynamic effects are of low-frequency range, or between 0 to 100 Hz. A model of the finite element method, Plaxis 2D is used to validate the vibrational response of the receiver footing, concerning the effects on the far field. The soil foundation is very compressible, subjected to a vibration at different excitation frequencies. The movement of particles on the free domain of the soil surface at a distance of 50 m apart from the source of excitation results in a differential settlement for points within a receiver footing. And the displacement responses of the structure are analysed both in time domain and frequency domain. The beneficial application of Matlab Simulink for solving specific problems in Engineering Mechanics is suggested.

Determination of the Friction Angle between the Wheat Ear and Stripper Fingers

Introduction. Determining the angle of friction between stripper fingers and a wheat ear is an important task aimed at finding the optimal design parameters and operating modes of stripping devices. When stripper fingers and wheat ears interact, the relative position of the ear glumes, flower glumes, and grains is densified. In this case, the spikelet surface roughness changes. Materials and Methods. A series of experiments was carried out to determine the angles of friction between a steel stripper fingers and wheat ears. Wheat varieties “Moskovskaya 40” and “Moskovskaya 56” were selected for the study. The experimental measuring installation is a frame with a rotatable platform mounted on it with the adjustable angle of rotation. The goniometer head provides the ability to fix the platform rotation angle value. The weight suspended from the stem of the plant imitated the forces arising in the process of stripping. The width and thickness of the wheat ear were also measured and recorded. Results. The influence of the size of the wheat ear on the angle of friction is determined. The results of the study are divided into two groups. The following values of the friction angles were obtained: 26.4–31.5° for the wheat with ear width of less than 10.4 mm; 22.0–27.1° for the wheat with ear width of more than 10.4 mm. Discussion and Conclusion. The angles of friction of wheat ears on the stripper fingers for wheat varieties specific to the Central region are obtained. The dependence of the angle of friction on the ratio of the geometric dimensions of the wheat ear and the slit width of the stripper fingers is established. When a wheat ear width is less than 10.4 mm, an effect of pinching the spikelets between the stripper fingers was observed. In this case, the coefficient of friction noticeably increased.

Software for motion analysis of devices installed on polymer shock absorbers

A description of the method and program for solving the problem of analyzing the motion of the device installed on the polymer shock absorber is given. The equation of dynamics using a small parameter is used to describe the motion of the device. The values of displacement and rotation angle of the device is obtained by modeling the motion by solving integro-differential equations. The procedures of the Green’s functions building as well as grid methods are used. The influence of temperature on the properties of shock absorbers is taken into account by way of solving the three-dimensional problem of non-stationary thermal conductivity for a shock absorber in the form of a parallelepiped. The Fourier method of dividing variables is used as a method of solving this problem. Temperature distributions by shock absorber volume are set and analyzed. Than temperature values in nonlinear expression are used in the kernel structure in Boltzmann - Volterra equations. The critical mode of motion of the device, when external excitation has a fast growth mode, and temperature range exceeds one hundred Celsius degrees, is analyzed and the dependence of the motion of the center of mass of the device on time and temperature is obtained. The description of the software in which the presented methods of calculation for problems of nonstationary thermal conductivity and device dynamics are realized, is given. The program works in console mode, a window interface is developed for displaying graphs of functions. The examples of the program’s operation both the nonstationary heat conduction problem and for shock absorber’s dynamics are presented.

Impact of layer rotation on micro-structure, grain size, surface integrity and mechanical behaviour of SLM Al-Si-10Mg alloy

Selective laser melting (SLM) is one of the appreciable technologies that is directly used to manufacture the intricate and highly accurate parts within short period of time. However, the involvement of various parameters in SLM process is gaining more and more attention of the scientific community. In this work, the research efforts have been made to emphasize on the effects of one of the prominent parameters of SLM process i.e., layer rotation on the microstructure, grain size, surface topography, residual stresses and mechanical behaviour of selective laser melted Al-Si-10Mg alloy. The standard benchmark components were fabricated by varying the layer rotation values at three different angles i.e., 0°, 45° and 90°. The result of microstructural analysis (using EBSD, SEM and XRD) revealed that the Al-Si-10Mg produced the cellular structure having less pores and defects at 90-degree layer rotation angle. The grain size, residual stresses and surface roughness (77.02%) values were also reduced with increase in layer rotation angle values. Furthermore, the micro-hardness (upto 19.6 %), tensile strength, %elongation (87.29 %) and relative density values were significantly enhanced at higher angle of layer rotations mainly due to the reduction in porosity and better interlayer metallurgical bonding.

Methods of Predicting the Heading, Pitch and Roll Angles for an Unmanned Aerial Vehicle

The article discusses handicaps in predicting values of rotation angles with regard to Heading, Pitch and Roll for an Unmanned Aerial Vehicle. Within the simulation of the rotation angle values, the linear, polynomial and logarithmic methods were used. The programme source code was written in the numerical editor Scilab 5.4.1. The source data for investigation were recorded by a measuring device Trimble UX-5. The article provides results of comparing the real values of Heading, Pitch and Roll rotation angles to findings obtained from the prediction methods. Based on the conducted research, it was found that the largest value of standard deviation parameter in prediction of the rotation angles is for the angle of Heading, as it equals approximately 5o, whereas the smallest ones are for the Roll and Pitch angles, equalling less than 1.4o.

Shaking table tests of the seismic response of a utility tunnel with a joint connection

A utility tunnel is characterized by a large span and segmental underground structure, which will produce many joint connections in the practical engineering. The existence of joints will reduce the stiffness and integrity of the structure, and eventually influence the safety of the structure. In this paper, a series of shaking table tests of utility tunnels with and without a joint connection were conducted to assess the effects of a joint on the seismic behavior. Three types of earthquake waves under uniform excitation (the same excitation at different points of the ground) in the transverse direction were input. The results show that the structure without a joint connection presented a more significant acceleration response and horizontal soil pressure response than that with a joint connection. The peak strain and bending moment would be reduced with a joint connection. The relative displacement at two sides of the joints was very small under various types of earthquake waves, and only a small value of rotation angle was produced, indicating the insignificant response of joint deformation.