Torsional Analysis Research Articles

3D torsional experimental strain modal analysis for structural health monitoring using piezoelectric sensors

Modal analysis is a dynamic response-based experimental structural identification procedure widely used for condition assessment and structural health monitoring (SHM). Piezoelectric sensors are smart material-based dynamic strain sensors being progressively implemented in vibration-based monitoring techniques. However, these have been so far limited to preliminary investigations on 1D and 2D structures with regard to modal analysis. Strain modal analysis using piezoelectric sensors has so far utilized only lower bending modes for frequency and mode shape-based SHM. This paper aims to evaluate the piezoelectric sensors for modal response measurement, modal parameter identification, and structural health monitoring of 3D structures, especially using torsional modes. It reports a comparative experimental study between the piezoelectric sensors and the accelerometers for dynamic response measurement, modal parameter extraction and damage identification and localization. Experimental modal analysis using impact hammer-based excitation is performed on two lab-sized specimens under different boundary conditions. Displacement mode shapes from both the sensors are used to determine the location and the severity of the damage. Torsional and bending modes are studied distinctly for sensitivity towards damage monitoring. Modal assurance criteria (MAC), coordinated MAC (CoMAC), and modal strain energy (MSE) are adopted as damage indicators. Results of the study show that the piezoelectric sensors are equivalent to accelerometers for response measurements and modal parameter extraction. They possess enhanced sensitivity towards damage monitoring as compared to accelerometers. Torsional modes perform better than bending modes for damage localization and severity quantification. Bending modes from both sensors are ineffective in locating the damage precisely. Modal strain energy (MSE) based damage index from torsional modes acquired from piezoelectric sensor performs best in terms of sensitivity towards damage location and exhibits peak severity, especially for incipient damage. The study establishes piezoelectric sensors as reliable and cost-effective modal response sensors.

Evaluation of natural frequency, Campbell diagram and forced torsional vibration of deepwell pumps for the marine, oil and gas industry

Deepwell marine and offshore pumps need to design in a way to present high performance and reliable lifetime. Deepwell pumps should be designed in a way to operate under offshore conditions. In order to investigate the resonance and find critical rotational speeds of the pump, it is needed to find the rotational natural frequency for undamped model. In order to avoid any resonance, the intersection points between natural frequency and excitation (1X and 2X) should not be in the interval of 90%-110% of operating speed, based on API standard (API 610). Deepwell pump structure is combination of motor, motor-shaft coupling and pumping configuration. Based on the size of tank and type of ship the length of whole deepwell pump can be more than 40 meters. Elastic rotating shafts connect with appropriate shaft-couplings with needed numbers of impellers and inducer. Small and linear angle of rotation theory are used to extract natural frequencies of deepwell pumps. Different damping scenarios are illustrated in detail. Holzer method is implemented to analyse torsional forced vibration. Free-free boundary conditions considered. Combination of discrete model, lumped mass model and finite element method are employed to present the Campbell diagram. Parametric strategy is used for forced torsional vibration analysis. It is found that how to model and consider the effective length of intermediate shaft in pumping configuration has effect on second natural frequency. It is seen that the first natural frequency of the whole system is highly depended on modelling of motor-shaft coupling. The results are compared when the whole pump is model by lamped mass model and finite element model. Results of this paper suggest that combination of three mentioned methods is acceptable and accurate. It is shown that Holzer method is suitable for torsional forced vibration analysis. The developed codes are verified with findings in the literature.

Torsional static and vibration analysis of functionally graded nanotube with bi-Helmholtz kernel based stress-driven nonlocal integral model

A torsional static and free vibration analysis of the functionally graded nanotube (FGNT) composed of two materials varying continuously according to the power-law along the radial direction is performed using the bi-Helmholtz kernel based stress-driven nonlocal integral model. The differential governing equation and boundary conditions are deduced on the basis of Hamilton’s principle, and the constitutive relationship is expressed as an integral equation with the bi-Helmholtz kernel. Several nominal variables are introduced to simplify the differential governing equation, integral constitutive equation, and boundary conditions. Rather than transforming the constitutive equation from integral to differential forms, the Laplace transformation is used directly to solve the integro-differential equations. The explicit expression for nominal torsional rotation and torque contains four unknown constants, which can be determined with the help of two boundary conditions and two extra constraints from the integral constitutive relation. A few benchmarked examples are solved to illustrate the nonlocal influence on the static torsion of a clamped-clamped (CC) FGNT under torsional constraints and a clamped-free (CF) FGNT under concentrated and uniformly distributed torques as well as the torsional free vibration of an FGNT under different boundary conditions.

Torsional vibration analysis of the surface‐mounted permanent magnet synchronous machine using analytical model considering flux harmonics

Torsional vibration analysis of the surface‐mounted permanent magnet synchronous machine using analytical model considering flux harmonics

Tibial torsion analysis in computed tomography: development and validation of a real 3D measurement technique

PurposePathological tibial torsion is known to negatively influence the functionality of the lower extremity, and therefore, its assessment might play an important role. While 3D imaging is used for many examinations of the musculoskeletal system, for the determination of tibial torsion no 3D measurement technique has been available so far. We developed a 3D measurement method and assess its interobserver reliability as well as its correlation with standard 2D measurement methods.MethodsCT scans of 82 tibiae in 79 patients with a mean age of 41 years were included. A novel 3D measurement technique was developed and applied. Measurements were compared with two frequently used 2D measurement methods. ICC (intraclass correlation coefficient) for the new technique was determined and compared to the 2D measurement method. Furthermore, differences between left and right legs as well as between males and females were assessed.ResultsThe ICC for the 2D methods was 0.917 and 0.938, respectively. For the 3D measurements, ICCs were calculated to be 0.954 and 0.950. Agreement between 2 and 3D methods was moderate to good with ICCs between 0.715 and 0.795. Torsion values for left and right legs did not differ significantly in 2D and in 3D (26.2 vs 28.5° and 27.2 vs. 25.9°). The same is true for the differences between male and female in 2D and 3D (26.2 vs. 29.6° and 25.0 vs. 31.2°).ConclusionThe newly developed 3D measurement technique shows a high intraclass agreement and offers an applicable opportunity to assess the tibial torsion three-dimensionally.

Analysis on dynamic eccentricity effect and torsional performance of steel reinforced concrete frame with special-shaped column

Based on the seismic simulation shaking table test of steel reinforced concrete frame model with special-shaped column, the lateral-torsional vibration response, dynamic eccentricity effect and nonlinear torsion response law of the model structure are studied. The results show that, under the action of three-way earthquake, the Y-direction and X-direction horizontal torsion coupling phenomena occur in the high-order vibration mode of the model structure, and the accidental eccentric torsion has a light influence on the seismic performance of the special-shaped column structure which does not exceed the height limit. The nonlinear torsion analysis shows that the inter-storey displacement angle of the model structure is affected by floor position, eccentricity and ground motion intensity. As the eccentricity and seismic intensity increases, the inter-storey torsion Angle of the model structure increases constantly. In case the relative eccentricity is less than or equal to 0.5 and the peak acceleration is less than or equal to 0.62g, then the amplitude of the inter-storey torsion Angle of the model increases slightly; In case the relative eccentricity is more than 0.5, then the lateral-torsional coupled effect of earthquake response of the structure is obvious, and the influence of eccentricity on torsion effect of the model structure is more obvious. The results show that steel reinforced concrete frame with special-shaped column has good ductility and torsion resistance.

Coupled flexural torsional analysis and buckling optimization of variable stiffness thin-walled composite beams

Present work examines flexural–torsional coupling for static and stability analysis of thin-walled composite beams having variable stiffness. Variable stiffness composites (VSCs), manufactured with curvilinear fibers, are considered in this work. Compared to straight fiber laminates, variable angle tow (VAT) sections may significantly improve structural response as they redistribute the in-plane stresses. A generalized beam kinematic model which considers the effect of flexural, torsional and, warping deformation is adopted and using the principle of minimum potential energy, governing equations are derived. The variable fiber angles can be defined using a general Lagrangian polynomial and as a particular case, the solution is presented for linearly varying fiber angles. Stability analysis considers geometric nonlinearity. The present model neglects transverse shear deformations, and governing equations are numerically solved using a set of C 1 continuous finite elements. Important observations are made on the coupled response of thin-walled VSCs for static and stability analysis, which indicates the necessity of optimization study. An efficient ‘Teaching Learning Based Optimization’ (TLBO) algorithm is applied to obtain the most efficient curvilinear fiber path. The results show that lateral torsional buckling load capacity can be increased by approximately 15% in optimized VSCs compared to unidirectional fiber composites. The present kinematic model and numerical scheme can be easily extended to the optimization studies considering manufacturing constraints, which may be further implemented in commercial designs.

Analysis of Subsynchronous Torsional of Wind–Thermal Bundled System Transmitted via HVDC Based on Signal Injection Method

With the development of large-scale new energy, the wind–thermal bundled system transmitted via high-voltage direct current (HVDC) has become the main method to solve the problem of wind power consumption. At the same time, the problem of subsynchronous oscillation among wind power generators, high-voltage direct current (HVDC), and synchronous generators (SGs) has become increasingly prominent. According to the dynamic interaction among doubly fed induction generators (DFIGs), HVDC, and SGs, a linearization model of DFIGs and SGs transmitted via HVDC is established, and the influence of the electromagnetic transient of wind turbines and HVDC on the electromechanical transient processes of SGs is studied. Using the method of additional excitation signal injection, the influence of the main factors of DFIG on the damping characteristics of each torsional mode of SG is analyzed, including control parameters and operation conditions when the capacity of HVDC is fixed. The mechanism of the negative damping torsional of SGs is identified. A time-domain simulation model is built in Electromagnetic Transients including DC/Power Systems Computer Aided Design (EMTDC/PSCAD) to verify the correctness and effectiveness of the theoretical analysis.

Torsional buckling analysis of MWCNTs considering quantum effects of fine scaling based on DFT and molecular mechanics method

In this paper, quantum and molecular mechanics are used to study the quantum effects of fine scaling on the buckling strength of multi-walled carbon nanotubes (MWCNTs), as well as the effects of changes in length, diameter, chirality, wall number and length-to-diameter ratio of the structure under torsional loading. To this end, the total potential energy of the system is calculated with the consideration of both bond stretching and bond angular variations. The density functional theory (DFT) along with the generalized gradient approximation (GGA) function is used to obtain the relevant elastic constants of the nanotubes. The study shows that the quantum effects of fine scaling cause more buckling strength of the structure against external torsional loadings. Also, with any longitudinal change as well as the changes in the structural arrangement that reduce the quantum effects of fine scaling, the strength of the structure decreases sharply.

Effect of the torsional vibration depending on the number of cylinders in reciprocating engines

This paper is aimed to explore the effect of increasing the number of pistons on the torsional vibration analysis of inline reciprocating machines with simplifications of equivalent masses to the connecting rod and crankshaft. A mathematical model of a mechanism of two degrees of dynamic freedom has been used to develop the equations of motion of the rotating and reciprocating parts of the single and multi-cylinder engine. Different configurations of single-cylinder and multi-cylinder engines are considered with the number of cylinders ranging from 1 to 6. The model of the crankshaft is established with the use of Lagrange's equations valid for a single and multi-pistons engine. This work shows the relation between the angular displacement of the crank angle and the twist angle of the crankshaft concerning three different damping coefficients. The maximum amplitude occurred with an engine of 2-cylinders while the minimum amplitude occurred with the single-cylinder engine. The twist angle does not depend upon the increasing number of the pistons. The torsional vibrations of the crankshaft by using 3 or more cylinders are significant in magnitude with values near to unity. Besides, the greatest amplitude of twist angle with odd cylinders and the reduction in the torsional vibration may be obtained for engine designs with even cylinders.

Design & analysis of multiple operational tool holder with considering the plain drilling & boring operation under maximum torque conditions

Abstract The quality with computer features is greatly influenced by the movement of machine resulting from process of cutting. Most publications ignore the influence of the person in charge of the tools; this paper considers the dynamic performance of the entire cutting system consisting of a spindle, tool holder, tool and tools. Therefore the vibration performance research is performed to describe the hot and efficient state of the competitive equipment storage technology, namely heatshrink (HS) and hydraulic (HE) expansion. It is shown that HE has higher levels of HS. Therefore, HE has shown good features, 10% higher productivity and up to 300% accessibility of tools. High quality during high performance cutting, good gravity quality of the whole system, built with functionality, tool, tool holder, cracks and machine structure are essential. Available ways to improve the performance of machine tools focus solely on the reduction of directing spindles and machine tool properties, ignoring the influence of the person in charge of the tools, considers different technologies for handling tools, focusing on their influence on the production and life of the tool. Due to the simple limitations of the parameters for making the machine structure model, most of the simulation models available ignore the technical impact of the tool contrast. However, due to the technical differences between the many techniques of assembling the tool, a major impact on the operation of the process machine should be considered. This will lead to different vibration symptoms, which directly affect the quality of operation, as well as the production of digestive processes and the health of the tool. In this the analysis of Tool head for torsional load & Analysis of Tool Holder under the action of axial load is carried out.

Torsional vibration factor analysis and reduction for refrigerator equipped with top-mounted compressor

Torsional vibration factor analysis and reduction for refrigerator equipped with top-mounted compressor

Design, stimulation and fabrication of chassis of an FSAE female driven vehicle

Abstract Formula student competitions are a type of design and fabrication competition held across the world. Chassis is a very important component of any vehicle which is designed keeping in mind all the other components of vehicle like suspension, brakes, engine requirements, etc. as well as ergonomics and driver comfort as per the rules of the competition This study focuses on design, optimization and ANSYS analysis of a chassis designed around a 95-percentile male dummy as well as female driver comfort. The chassis was tested for front bulkhead impact, rear bulkhead impact, vertical bending and torsion analysis under static conditions and optimized to give a design with least weight, least cost in manufacturing and fabrication, maximum possible torsional rigidity and safety. A spaceframe chassis was designed using cold rolled tubes of AISI 1018 using SolidWorks and tested on ANSYS at all major points of force applications. 1.22 FOS was obtained in front bulkhead impact test, 1.7 FOS was obtained in rear bulkhead impact test, FOS of 1.15 was obtained in torsion test and 1.49 FOS was obtained in vertical bending test of the chassis in FEA analysis. The chassis obtained had the optimum values of safety and comfort and provided cheapest method for manufacturing.

Coupled bending and torsional vibration characteristics analysis of inhomogeneous wind turbine tower with variable cross section under elastic constraint

The separation of cross section’ mass center from its centroid will lead to coupled bending and torsional vibration of the wind turbine tower (Referred to as tower). Three governing differential equations of vibration of the tower with inhomogeneous material and variable cross section are formulated based on D'Alembert's principle and Euler-Bernoulli beam theory. Considering the installation and operation factors of the wind turbine, the dimensionless natural frequencies and mode shapes of the tower under multiple constraint conditions are obtained by the differential quadrature method. Compared with those available in the literature, numerical results demonstrate the accuracy and validity of the proposed method. A series of parametric study is accomplished to reveal the influence of the foundation stiffness, wall thickness, eccentricity, and the ratio of the inner diameter of the top and bottom cross section of tower on the vibration characteristics of tower. The frequencies veering for the mode of tower is discussed. These numerical results have guiding significance for the design of tower.

Design and Torsional Rigidity Analysis on Frame of Formula Garuda 17 Based on Student Formula Japan 2017 Rules

The objective of this study are to: (1) Produce the design of the Formula Garuda 17 car that complies with Student Formula Japan 2017. (2) Produce the frame design of the Formula Garuda 17 car that has a torsional rigidity that can withstand bending and twisting loads. The type of research used is research and development, also known as R & D, and the development model of the Formula Garuda 17 car frame, which is a model for developing Analysis, Design, Development, Implementation, and Evaluation (ADDIE). The results showed that the frame design was in accordance with Student Formula Japan 2017 regulation, and the torsional rigidity value met the target of 1,026.7NM / degree while the Factor of safety value in the bending force was 3.3 so that this frame was categorized as safe for the race.

Non-uniform torsion analysis of functionally graded beams with solid or thin-walled section using hierarchical Legendre expansion functions

In this paper, an accurate yet computationally efficient beam model based on hierarchical Legendre expansion functions is developed for the analysis of non-uniform or restrained torsion problems of Functionally Graded (FG) beams with solid or thin-walled section. The mechanical properties of the FG beams studied in this paper, such as Young’s modulus and shear modulus, are assumed to continuously vary along either the length or thickness direction following a power-law distribution. The proposed beam model is based on the assumption that the beam’s cross-section is infinitely rigid in its own plane. However, the longitudinal displacement field over the beam’s cross-section is enriched in an element-wise manner by the unknown longitudinal displacement parameters multiplying with hierarchical Legendre expansion functions. The proposed modeling methodology has two novel aspects: First, it allows the torsional or twisting angle, which is a priori defined as an unknown kinematic variable, to be directly captured without a post-processing recovery step, even if there exists a strong flexual-torsional coupling within the beam; second, the longitudinal warping response of the beam, triggered by stretching, bending, twisting, or the coupling between them, can be captured without the pre-determination of warping modes and at a lower level of DOFs. The strong-form governing equations of non-uniform or restrained torsion problems of the FG beam are derived based on the principle of minimum potential energy and is directly solved by the high-quality general-purpose ordinary differential equation (ODE) solver, i.e. COLSYS ODE solver. Also, a more efficient Rayleigh-Ritz energy method is applied to provide the weak-form solutions. The resulting beam model is suitable to a more general cross-section, such as solid section, branched open section, or half open-half closed section. The accuracy and efficiency of the proposed beam model are validated extensively by comparing with the previously published results in literature. Effects of the power-law index, taper ratio, and section-type on the torsional response of FG beams with material gradation along length or thickness direction are studied with various numerical examples.

Identification of BRaf-Sparing Amino-Thienopyrimidines with Potent IRE1α Inhibitory Activity.

Amino-quinazoline BRaf kinase inhibitor 2 was identified from a library screen as a modest inhibitor of the unfolded protein response (UPR) regulating potential anticancer target IRE1α. A combination of crystallographic and conformational considerations were used to guide structure-based attenuation of BRaf activity and optimization of IRE1α potency. Quinazoline 6-position modifications were found to provide up to 100-fold improvement in IRE1α cellular potency but were ineffective at reducing BRaf activity. A salt bridge contact with Glu651 in IRE1α was then targeted to build in selectivity over BRaf which instead possesses a histidine in this position (His539). Torsional angle analysis revealed that the quinazoline hinge binder core was ill-suited to accommodate the required conformation to effectively reach Glu651, prompting a change to the thienopyrimidine hinge binder. Resulting analogues such as 25 demonstrated good IRE1α cellular potency and imparted more than 1000-fold decrease in BRaf activity.

On modelling of simulation model for racing car frame torsional stiffness analysis

This paper concerns the modelling of the simulation structure for the torsional stiffness evaluation of a Formula SAE vehicle frame and presents some insights into the modelling of the problem using a beam-like model together with geometrical simplifications. The insights consist of presenting utilized simplifications and assessing their influence on torsional stiffness. The simulation model, consisting of the vehicle frame, suspension and testing fixture of complex shapes, requires certain simplifications to achieve a sustainable modelling and computational time while getting reasonable results. The influence of simplifications such as a linear isotropic material model for carbon-fibre and geometrical simplifications of the suspension, frame and testing fixture are discussed. The simulation model was developed in such a way to allow the easy change of cross-sections and geometry during the vehicle design process. The simulation model was also experimentally validated. A comparison of the results from the simulation and testing showed an acceptable difference (up to 10%), thus a small influence of the material and geometrical simplifications on the results of torsional stiffness is considered.

Torsional beam analysis subjected to static load on offshore structure deck

The jack-up is one of the fixed typical offshore structures consists of many elements such as beams, plates, braces and so on. Those elements play an important role to strengthen the structure locally and globally from internal and external loads. Such kind of loads eventual act on element like beam and make torsionally. This phenomenon must be analyzed because the beam is connected to other element. The objective of the present study is to analyze the torsional beam subjected to static load on offshore structure deck. The jack-up structure particularly beam element located on the deck is selected to be analyzed. Two cases of beam model are taken. The numerical method is performed to analyze the beam. The result obtained by numerical method for two beam model si compared with one another.

Influence of spatially varying material properties on the bimoment normal and shear stresses by warping torsion of FGM beams

In this contribution, which is an extension of author’s research [1,2], an influence of the in two and three directions varying material properties on non-uniform torsion of the Functionally Graded Material (FGM) thin-walled beams is originally investigated. Based on the semi-analytical solution of the fourth order differential equation for non-uniform torsion, the local finite element equations of the twisted FGM beam are presented, considering the non-uniform torsion with effect of warping and secondary deformations due to the angle of twist. The warping part of the first derivative of the twist angle caused by the bimoment is considered as an additional degree of freedom at the beam nodes. The Multi-Layers Method (MLM) [3], and the Reference Beam Method (RBM) [4] are extended for homogenization of the spatially varying material properties and relevant stiffnesses in the real beam onto effective longitudinally varying ones in the homogenized beam for the load case of non-uniform torsion.The focus of the numerical investigation, with consideration of the warping and Deformation Effect due to the Secondary Torsional Moment (STMDE), is on elastostatic analysis of straight FGM beams with rectangular hollow cross-sections. The influence of the variation of the material properties with respect to two or three directions on the angle of twist and the bimoment normal and torsional shear stresses is investigated. The obtained results are compared with the ones calculated by a very fine mesh of standard solid finite elements. This FGM warping non-uniform torsion beam finite element can be used not only in torsional analysis of general thin-walled beams but also in the design of FGM sensors and actuators in mechatronics.