Normal Deflection Research Articles

A REVIEW AND BUCKLING ANALYSIS OF STIFFENED PLATE

It happens many times that the structure is safe in normal stress and deflection but fails in buckling. Buckling analysis is one of the method to go for such type of analysis.It predicts various modes of buckling. Plates are used in many applications such as structures, aerospace, automobile etc. Such structures are subjected to heavy uniformly distributed load and concentrated load many times over it’s life span. Strength of these structures are increased by adding stiffeners to its plate. This paper deals with the analysis of rectangular stiffened plates which forms the basis of structures. A comparison of stiffened plate and unstiffened plate is done for the same dimensions. In order to continue this analysis various research papers were studied to understand the previous tasks done for stiffened plate. Hyper mesh and Nastran is used in this research work.Buckling analysis is performed for the component with aspect ratio of 2.Rectangular flat bar is used as stiffener

Modeling Methodology of Flexible Milling Force for Thin-Walled Component on High Speed Peripheral Milling Processing System

This study has developed a model in order to show the relationship between deflection of the low-rigidity processing system such like thin-walled component and the flexible milling force. The new model takes the deflection of cutter-workpiece system into account. The cutting force is analyzed simulatively by utilizing modified Newton–Raphson iterative algorithm. The simulative results show that the total normal deflection of workpiece–cutter system is the main factor affecting the change of cutting force.

Investigation into use of piezoelectric sensors in a wheeled robot tire for surface characterization

A differential steered, 13.6kg robot was developed as an intelligent tire testing system and was used to investigate the potential of using piezoelectric film sensors in small tube-type pneumatic tires to characterize tire–ground interaction.The robot was instrumented with low-cost piezoelectric film sensors between the inner tube and the tire. An unlaminated and a laminated sensor were placed circumferentially along the tread and an unlaminated sensor was placed along the sidewall. The analog signal passed to the robot via a slip ring. The robot was tested with a controlled power sequence carried out on polished cement, ice, and sand at three power levels, two payload levels, and with two tire sizes.The results suggest that the sensors were capable of detecting normal pressure, deflection, and/or longitudinal strain. Added payload increased signal amplitude for all sensors. On the smaller tires, sensors generally recorded a smaller, wider signal on sand compared to cement, indicating potential to detect contact patch pressure and length. The signals recorded by the unlaminated sensor along the tread of the smaller tire were smaller on ice than cement, indicating possible sensitivity to tractive force. Results were less consistent for the larger tires, possibly due to the large tread pattern.

Buckling of Elastic Thin Films on Compliant Substrates for Determination of Surface Parameters

The buckling of an elastic thin film on a compliant substrate under small perturbation in normal deflection and tangential displacement is studied with the effect of surface energy and interfacial slip. It is revealed that Poisson's ratio of the soft substrate and the interfacial slip can be neglected for film's thickness smaller than tens of nanometers. The effect of surface energy nevertheless renders the critical strain for the onset of wrinkling and the wave length dependent on the thickness highly nonlinearly. The potential of using buckling of thin films on compliant substrates for determination of surface parameters has been discussed.

A Novel Evolutionary-Based Cooperative Spectrum Sensing Mechanism for Cognitive Radio Networks

Cognitive radio (CR) is considered as a feasible intelligent technology for 4G wireless networks or self-organization networks and envisioned as a promising paradigm of exploiting intelligence for enhancing efficiency of underutilized spectrum bands. In CR, one of the main concerns is to reliably sense the presence of primary users, to attain protection against harmful interference caused by the potential spectrum access of secondary users (SUs). In this paper, evolutionary algorithms, namely, genetic algorithm (GA) and particle swarm optimization (PSO) are investigated. An imperialistic competitive algorithm (ICA) is proposed to minimize error detection at the common soft data fusion (SDF) center for structurally centralized cognitive radio network (CRN). By using these techniques, evolutionary operations are invoked to optimize the weighting coefficients applied on the sensing measurement components received from multiple cooperative SUs. The proposed method is compared with other evolutionary algorithms, as well as other conventional deterministic, such as maximal ratio combining- (MRC-), modified deflection coefficient- (MDC-), normal deflection coefficient- (NDC-) based SDF schemes and OR-rule HDF based. MATLAB simulations confirm the superiority of the ICA-based scheme over the PSO-, GA-based and other conventional schemes in terms of detection performance. In addition, the ICA-based scheme also shows promising convergence and time running performance as compared to other iterative-based schemes. This makes ICA an adequate solution to meet real-time requirements.

Application of Optoelectronic Liquid Lever Sensor in Urban Bridges Deflection Monitoring

The deflection which reflects the bridge linear variety is an important parameter for the evaluation of bridge safety. According to the structural characteristics of urban bridges, the connected pipe optoelectronic liquid level sensor system is a novel kind of sensor for detecting the connected pipe liquid level, which can be applied for multipoint, long-period, online, remote, automatic measurement of bridge deflection, it is not affected by the dust, humidity and fog in the urban bridge health monitoring and maintenance. At present, the system has been integrated and applied in the project of main roads bridge Online Safety Monitoring Management System in Hangzhou (Phase II), a web-based urban bridge cluster monitoring system have been established since 2007. According to a tied arch bridge case studies, the measuring data show that the system not only can accurately collect the bridge normal deflection information and variety, but also successfully monitored the structural responses due to the Wenchuan earthquake on May 12, 2008. About two-minute abrupt changes in displacement amplitude were observed in the measured signals starting at 14:37, about 9 minutes later than the earthquake’s occurring. The results shows, it is an effective method for the real-time monitoring of urban bridge deflection.

A simple and inexpensive optical technique to help students visualize mode shapes

An imaging technique is introduced that is suitable for visualizing the mode shapes of vibrating structures in an educational setting. The method produces images similar to those obtained using electronic speckle pattern interferometry (ESPI), but it can be implemented for less than 1/10 the cost of a commercial ESPI system, and the apparatus is simple enough that it can be constructed by undergraduate students. This technique allows for real-time visualization of the normal modes and deflection shapes of harmonically vibrating structures, including those with shapes that make generating Chladni patterns with sand or powder impossible. The theory of operation and construction details are discussed.

Analytical Modeling of CMUTs in Coupled Electro-Mechano-Acoustic Domains Using Plate Vibration Theory

This paper proposes an analytical capacitive micromachined ultrasonic transducer (CMUT) model that couples three physical domains using plate vibration and radiation theories. The model accounts for the spatial distribution of the normal deflection over the CMUT cell membrane. A mode superposition expression is used to capture the complicated flexural-plate-like movement. We compare the results of analytical calculations using the proposed plate model with those of finite-element modeling, together with the analytical results of the piston-like models. This approach shows promise for more detailed and convenient physical modeling of CMUTs, which could lead to new ways of designing and controlling them.

Experimental Study on the Flexural Behavior of Concrete Beam Reinforced With HRBF500 Steel Bars

In order to investigate the flexural behavior of concrete beam reinforced with 500MPa fine grain high steel bars, four rectangle cross-section concrete beam subjected to static bending test were made. Mechanics characteristic, flexural capacity of normal section, crack and deflection were analyzed according to current related China code. The results show that the flexural behavior of concrete beam reinforced with 500MPa fine grain high steel bars is similar to normal concrete beam, the average strain of concrete section keep plane; flexural capacity and average crack spacing could still calculated by current code for their values coincide well with tested value; however, deflection values of the specimens calculated by current related China code are smaller than corresponding tested value; under the state of serviceability, crack width and deflection of the specimens were found not to meet the requirement of current China code while the design value of yield strength of 500MPa fine grain steel bar was taken more than 360MPa.

Mechanical properties of automotive tyres

The paper considers mechanical characteristics of automotive tyres. The authors show that influence of lateral force on a wheel not only causes lateral deformation of the tyre, but also increases her normal deflection.

Ph.An.Ty.M.H.A.: a physical analytical tyre model for handling analysis – the normal interaction

A new analytical–physical tyre model for which the paternity has to be ascribed to Professor Giuseppe Capone was developed at the Department of Mechanical Engineering for Energetics at Naples University ‘Federico II’ with the support of the Bridgestone Technical Centre Europe. The whole model allows to obtain the road–tyre interactions so it can be used in vehicle dynamic simulations. The model has been named Ph.An.Ty.M.H.A., acronym of ‘PHysical ANalytical TYre Model for Handling Analysis’ and it includes the normal, longitudinal and lateral tyre–road interaction. Considering that Ph.An.Ty.M.H.A. is an analytical ‘deductive’ model, it is necessary to develop it starting just from the normal interaction, described in this paper, and then the other ones will be described in future papers. In fact, the normal interaction, i.e. the relationship between the normal load and the normal deflection, influences the tangential (longitudinal plus lateral) one, which determines the vehicle handling behaviour. The parameters used in this model are physical and geometrical so they can be measured on the real tyre. This property allows to better understand the tyre–road interaction mechanism. The tyre behaviour is modelled by analytical expressions based on equilibrium conditions and geometrical relations. To reproduce the experimental normal interaction and the pressure distribution, once the tyre geometrical quantities are known, it is necessary to identify some parameters, related to the tyre structure, by a comparison with the experimental data. Moreover, the predictive ability of the whole model, combined with a vehicle model, is very careful in analysing the vehicle handling [J.C. Dixon, Tyres, Suspensions and Handling, Cambridge University Press, Cambridge, 1991].

Detector effects in photothermal deflection experiments

We report on the theoretical analysis of a detector type influence on the normal deflection signal in photothermal experiments. Two cases are examined. In the first, the quadrant photodiode was considered as the detector; in the second the signal from the position detector, which measures the central moment displacement of the probe beam, was analyzed. Both analyses were carried out within the framework of the complex ray theory. The normal photodeflection signal was found to depend on the type of detector used in the photothermal deflection experiments for some parameters of its setup.

Sonoclot Analysis for the Point of Care Diagnosis of Hyperfibrinolysis During Orthotopic Liver Transplantation

Abstract To properly and effectively manage coagulation disorders during orthotopic liver transplantation, clinicians need reliable and rapid data. From this point of view, the diagnosis of hyperfibrinolysis can be particularly challenging. Among 40 cirrhotic patients consecutively undergoing orthotopic liver transplantation at our center, 11 (27.5%) showed coagulopathy during the surgical procedure. In 5 (45.4%) of them, the Sonoclot analysis diagnosed hyperfibrinolysis (normal onset, rate, and peak but abrupt deflection toward the baseline), whereas traditional laboratory tests on simultaneously drawn blood samples showed no significant changes from their baseline values. The administration of intravenous tranexamic acid stopped the bleeding and normalized the Sonoclot trace in all of them. In the remaining 6 (54.6%) patients, both the Sonoclot analysis and the laboratory tests highlighted blood coagulation factor deficiencies, which were treated with fresh frozen plasma or platelets. The turnaround time was 23.8 ± 3.5 minutes for the Sonoclot analysis and 54.2 ± 7.2 minutes for the traditional laboratory tests. Although not widely used, in our experience the Sonoclot analysis provides rapid and useful data for the recognition and the management of hyperfibrinolysis, a coagulation disorder where simple and reliable laboratory tests are not available within sufficiently short times to satisfy intraoperative clinical needs.

Pattern instability of functionally graded and layered elastic films under van der Waals forces

This paper investigates surface instability of a functionally graded and layered elastic film interacting with another flat rigid body [or interacting with another functionally graded and layered elastic film (or simply-supported elastic plate)] through surface van der Waals forces under plane strain conditions. The shear modulus in each functionally graded layer is assumed to be exponentially varied in the thickness direction. A homogeneous elastic layer, which is the focus of this research, can be considered as a special case of the functionally graded layer by taking the magnitude of the gradient parameter to be very small. The solution for any functionally graded layer is obtained in terms of the pseudo-Stroh formalism; then the solution for the multilayered system is derived based on the transfer-matrix method. As a result the displacement and traction vectors at the top surface of the layered film (or plate) can be expressed in terms of those at the bottom surface of the layered film (or plate). We can thus obtain simple relationships between the surface normal traction and surface deflection. Expressions for the interaction coefficient as a function of the wave number of the instability mode are therefore obtained. The critical value of the interaction coefficient for surface instability and the associated instability mode can be determined easily by identifying the minimum of the interaction coefficient. An advantage of the present method lies in that it is very convenient to address a film (or a plate) with an arbitrary number of layers. The correctness of the present approach is verified by comparison with known results. The results show that it is possible to find N distinct surface instability modes for an N-layered elastic film interacting with another flat rigid body; and that it is also possible to find that there are at most N1+N2 distinct surface instability modes for an N1-layered elastic film interacting with another N2-layered elastic film. When a multilayered elastic film interacts with a simply-supported multilayered elastic plate, the film-plate system will exhibit the instability mode of the film or that of the plate depending on the stability strength of the plate versus that of the film.

Application of the diffraction theory for photothermal deflection to measurements of thermophysical and mass-diffusion properties of gases

The application of recently developed diffraction theory for cw transverse photothermal deflection spectroscopy (normal deflection only) to the measurements of thermophysical and mass-diffusion properties of gases is presented. Compared with the traditional ray-optics theory, the diffraction theory has one more term in the phase signal. This term quantitatively exhibits the probe-beam size effect on the phase signal. Experimental results demonstrated that even if the ratio of the probe-beam radius to the thermal diffusion length of a deflecting medium was as low as about 0.22, the probe-beam size effect could not be ignored when measuring the distance between the probe beam and a solid sample using the phase signal. With the measured distance, the thermal diffusivity α g and the temperature coefficient of the refractive index dn/dT of pure gases (Ο 2 , N 2 , and CO 2 ) and binary gas mixtures (CO 2 -O 2 and CO 2 -O 2 ) were precisely measured, resulting in good agreement with literature values. Furthermore the measured dn/dT values of the pure gases had one more significant figure than the literature ones. The concentration dependences of α g and dn/dT were employed for the determination of mass-diffusion coefficients of CO 2 -Ο 2 and CO 2 -N 2 , and the results were consistent with literature values.

Size-dependent response of ultra-thin films with surface effects

A modified continuum model of elastic films with nano-scale thickness is proposed by incorporating surface elasticity into the conventional nonlinear Von Karman plate theory. By using Hamilton’s principle, the governing equations and boundary conditions of the ultra-thin film including surface effects are derived within the Kirchhoff’s assumption, where the effects of non-zero normal stress and large deflection are taken into account simultaneously. The present model is then applied to studying the bending, buckling and free vibration of simply supported micro/nano-scale thin films in-plane strains and explicit exact solutions can be obtained for these three cases. The size-dependent mechanical behavior of the thin film due to surface effects is well elucidated in the obtained solutions.

Simultaneous in Situ Reflectance and Probe Beam Deflection Measurements at Solid Electrode−Aqueous Electrolyte Interfaces

A method is herein described for performing simultaneous in situ normal incidence reflectance spectroscopy (DeltaR/R, lambda = 633 nm) and probe beam deflection (PBD) measurements at solid electrodes in aqueous electrolytes, while scanning the potential linearly between two prescribed limits. Results obtained for Au in 0.1 M HClO4 and for Pt in both 0.1 M HClO4 and 0.1 M NaOH were found to be in excellent agreement with those reported in the literature for each individual spectroelectrochemical technique under otherwise similar conditions. Data collected for Pt electrodes in CO-saturated 0.1 M HClO4 revealed rather sudden changes in both DeltaR/R and PBD signals in the voltammetric region where the characteristic sharp peak associated with the oxidation of adsorbed CO occurs. This behavior was ascribed, respectively, to oxide formation (DeltaR/R) and to changes in the electrolyte composition in region neighboring the electrode, involving predominantly the acid concentration (PBD). In contrast, CO oxidation on Pt in 0.1 M NaOH yielded a PBD response consistent with formation of solution-phase carbonate via the reaction of the product, CO2, with hydroxyl ion. The exquisite sensitivity of DeltaR/R and PBD to interfacial phenomena was further illustrated using a monolayer of hemin irreversibly adsorbed on glassy carbon surfaces in 0.1 M Na2B4O7 (pH approximately 9.2). For this system, DeltaR/R was found to be proportional to the relative fractions of hemin and its reduced counterpart, while the PBD signal could be correlated with corresponding variations in the electrolyte concentration induced by the surface-bound redox process.

Configuration Selection, Modeling, and Preliminary Testing in Support of Constant Force Electrical Connectors

The recent introduction and advancements in design of simple, constant-force mechanisms have created the potential for small-scale, low-cost, constant-force electronic connectors (CFECs). CFECs differ from traditional connectors by the separation or disassociation of contact normal force and contact deflection. By removing the traditional constraints imposed by forces and deflections that are dependent on each other, new types of electronic connectors can be explored. These new designs may lead to smaller and more reliable electronic connectors. In this paper, constant-force mechanisms are adapted to satisfy current industry practices for the design of electronic connectors. Different CFEC configurations are explored and one is selected, prototyped, and used as a proof-of-concept connector for a personal digital assistant (PDA) docking station. The modeling, optimization, and verification of the prototype CFEC is presented. Adaptation of constant-force technology to electronic connectors creates new possibilities in electronic connector designs, including allowing an optimal contact force to be utilized to decrease the effects of fretting and wear, lowering required manufacturing tolerances, reducing the system’s sensitivity to variations introduced by the user, and increasing the system’s robustness in applications where movement or vibrations exist.

Tyre modelling for motorcycle dynamics

A tyre model based on simplifying mechanical assumptions is derived, which is, however, qualitatively valid over the whole region of possible operating conditions up to saturation. A one-dimensional brush model on the two-parameter Pasternak foundation is used, which is sometimes called the enhanced string model. The analysis is limited to the behaviour under steady-state conditions and under slow variations in these conditions; for this case the model can be reduced to a point contact model. The inputs to the tyre model are the normal tyre deflection, the camber angle, the longitudinal and lateral slips and the normal spin. The resultant normal, lateral and longitudinal forces and the aligning moment are the outputs. A difference from previous studies is the way in which the first-order relaxation is modelled; the relaxation lengths depend on the state of motion.

Hip mechanics after posterior structure repair in total hip arthroplasty.

This study investigated the rotational response of the hip with different repairs of posterior structures after using the posterior approach in total hip replacement. Five groups were tested: (1) the normal hip without a replacement, (2) the normal hip with a vented capsule, (3) no repair of the capsule and external rotators after total hip replacement, (4) repair of only the piriformis tendon, and (5) repair of the capsule and external rotators as a flap of tissue (capsule, piriformis, obturator internus, gemellae, and quadratus) to the posterior aspect of the greater trochanter. Hemipelvis cadaveric specimens were attached to a joint testing device for testing at full extension, 30 degree, 60 degree and 90 degree hip flexion as internal and external rotation was applied to the femur and the load deflection curves were recorded. Specimens after total hip replacement were externally rotated in full extension until dislocation occurred and the maximum torque was recorded. Each specimen then was rotated internally at 90 degree flexion to the point of dislocation and the maximum torque was recorded for comparison as well. The posterior approach had significantly decreased internal rotational support with no repair or only piriformis repair. When the capsule and external rotators were repaired, a more normal load deflection curve resulted when comparing the full repair group with the normal hip. Significantly higher torque was needed to dislocate the hip in flexion when a full posterior repair was done, and most specimens dislocated in flexion without complete failure of the repair.