Base Plate Research Articles

Dynamic responses of a train-track-bridge coupled system under earthquakes

The probability of a train running over a bridge when an earthquake occurs is increasing with the total mileage of China’s high-speed railway network expanding. To study this issue, a three-dimensional train-track-bridge dynamic interaction system subjected to seismic excitations is established based on commercial mathematical software. Besides, a set of motion equations of the system are derived according to the multibody dynamics, the finite element method theory and the bridge seismic theory. Moreover, in order to study the dynamic response of high-speed railway bridges under earthquake, a series of experiments are conducted on a scaled high-speed railway simple supported bridge model with a ballastless track slab excited by shaking table tests. Meanwhile, the strain of rails, track slabs, base plates and girder in various working conditions are measured by quasi-distributed optical fiber sensing stuck in bridge members. At last, the dynamic response of each structure member is demonstrated in the time and frequency domains. Furthermore, the seismic isolation performance of bridge members, such as fasteners, cement asphalt (CA) mortar layer and so on, is explained in details.

Vibration Fatigue Testing Procedure of High Strength MARS 600 Steel Fillet Welds Using Stainless Steel Consumable Electrode

Implementation of high strength steels in welded structural designs in the automotive, defence and construction industries is constantly increasing. Prolonged usage of such structures requires deep understanding of welded joint fatigue as well as a reliable and feasible life estimation methods development. Conventional fatigue testing methods often require costly, expensive in maintenance, high loading capacity equipment. They are also commonly restricted to specific specimen geometry and are time consuming due to the limit of a single specimen per test setup. This work presents high cycle fatigue (HCF) testing of high strength MARS 600 welded steel using a quick, simple and efficient resonance fatigue testing (RFT) method. The specimen is a simple cantilever fillet welded to a base plate using austenitic stainless steel 307L consumable electrode. Electrodynamic shaker is used for harmonic base excitation at a constant operating frequency. Several specimens welded to the common base are tested simultaneously, allowing completion of a high number of cycles and statistics in a relatively short time period. A hybrid, practical research approach combining experimental, finite element analysis (FEA), numerical and analytical calculations is presented. Fracture mechanics approach for fatigue life assessment is implemented. Crack growth calculation is based on the Paris - Erdogan law. Reduction in structural integrity due to crack propagation causes a reduction in natural frequency and transmissibility. The change in gain is evaluated via the open crack FEA model and integrated into the crack propagation algorithm. Resonance search, track and dwell module (RSTD) for maintaining constant gain throughout the test is not required. Fatigue life Wohler (SN) curve is constructed. Standard weld fatigue data is often provided for direct loading (tensile stress) and for different stress ratio (R) values. Corrections for mean stress and loading application are required. Current fully reversed (R = -1), indirect loading (bending stress) test results may be readily applied for random vibration fatigue analyses post processing. As expected, actual fatigue life results are higher compared to standard design curves, implying correctness of the manufacturing welding process of examined specimens. The presented procedure is of interest for research as well as for industrial welding processes testing, optimization and qualification.

Dosimetric effect of six degrees of freedom couch top with rotational setup error corrections in proton therapy.

To investigate the dosimetric effect of six degrees of freedom (6DoF) couch top with rotational corrections in proton therapy (PT). The water equivalent thickness (WET) was measured using a proton beam with a 6DoF couch top and patient immobilization base plate (PIBP) placed in front of a motorized water phantom. The accuracy verification was performed with the beam axis set perpendicular to the 6DoF couch top and tilted in 10° steps from 10° to 30°. Up to 3° rotational correction may be added during the actual treatment to correct the rotational setup error on our system. The measured and calculated values using the treatment planning system were compared. Additionally, the effect of the 3° difference was evaluated using actual measurements concerning each angle on the proton beam range. The WET of the 6DoF couch top and PIBP were 8.5±0.1mm and 6.8±0.1mm, respectively. The calculation and the actual measurement at each angle agreed within 0.2mm at the maximum. A maximum difference of approximately 0.6mm was confirmed when tilted at 3° following 30° with the 6DoF couch top plus PIBP. The dosimetric effect of the 6DoF couch top with rotational corrections in PT differs depending on the incidence angle on the couch top, and it increased with the increased oblique angle of incidence. However, the effect on the range was as small as 0.6mm at the maximum. The amount of rotational correction, the angle of incidence of the beam, and the effect of rotational corrections on the proton beam range may differ depending on the structure of the couch top. Therefore, sufficient prior confirmation, and subsequent periodical quality assurance management are important.

A numerical study integrated with RSM for hydrothermal and entropy performance of porous jet impingement

AbstractThe thermohydraulic and thermodynamic performance of porous jet impingement under pressure drop effect has not yet been jointly published. Thus, the novelty of this work computationally along with the response surface methodology (RSM) optimization approach considers the porous jet impingement performance linked with a pressure drop simultaneously. Also, the current study used a novel multiobjective optimum design study for various design parameters, such as porosity (ε), Darcy number (Da), and pore per inch (PPI), under numerical simulation assessment of forced laminar convection of jet impingement with full and partial metal foam. The influence of various base plate thicknesses (t = 0, 1, 2, and 3 mm), various nanofluids (Al2O3, CuO, SiO2, and ZnO), and the metal foam size percentage (W/L = 0, 0.25, 0.5, 0.75, and 1) on the improvement of the thermohydraulic and thermodynamic performance is also simulated. Results indicated that utilizing pure water and a metal foam size (W/L) of 1 along with a base plate thickness of 0 mm produced the preferable thermohydraulic and thermodynamic performance. Furthermore, according to an optimization analysis, the current study's objective for the thermohydraulic and thermodynamic performance of jet impingement can be achieved using the parameters porosity ε = 0.1, Darcy number, Da = 1, and the PPI = 15. Therefore, this investigation integrating computational fluid dynamics and RSM offers considerable innovation and useful reference for the optimum design of a porous jet impingement cooling.

Analysis of the Influence of the Motion State of Ultra-Thin Sapphire Based on Layer-Stacked Clamping (LSC).

Ultra-thin sapphire wafer processing is receiving increasing attention in the LED substrate industry. In the cascade clamping method, the motion state of the wafer determines the uniformity of material removal, while the motion state of the wafer is related to its friction coefficient in the biplane processing system, but there is little relevant literature discussing the relationship between the motion state of wafer and friction coefficient. In this study, an analytical model of the motion state of sapphire wafers in the layer-stacked clamping process based on the frictional moment is established, the effect of each friction coefficient on its motion is discussed, the base plate of different materials and different roughness are experimentally studied, the layer-stacked clamping fixture is prepared in this way, and finally the failure form of the limiting tab is analyzed experimentally. The theoretical analysis shows that the sapphire wafer is mainly driven by the polishing plate, while the base plate is mainly driven by the holder, and the rotation speed of the two is not the same; the material of the base plate of the layer-stacked clamping fixture is stainless steel, the material of the limiter is glass fiber plate, and the main form of failure of the limiter is to be cut by the edge of the sapphire wafer and damage the material structure.

Effect of eggshell powder on the microstructural and thermal behavior of Al7075/waste eggshell surface composites produced by solid-state friction stir processing developed for potential thermal applications

Lightweight composite materials for potential thermal applications are the contemporary demand for manufacturing and aircraft industries where the possibility to improve and tailor the desired properties is based on the application. Carbonized eggshell powder is a solid lubricant with absorbent capability and has proven as a reinforcement for metallic base composites. In the present work, an attempt is made to investigate the effect of carbonized chicken eggshell powder (3 to 9% by weight) on the microstructural and thermal properties of Al7075 alloy processed by solid-state friction stir processing. An infrared thermography and three K-type thermocouples equipped with the base plate at three equal distances are used to measure the temperature with respect to time. The comparative study of microstructure and grain structure analysis has been done by light microscopy, scanning electron microscopy, and electron backscattered diffraction methods. The findings explored the dynamic recrystallization and grain recovery with a reduced grain size of 6.2 to 10.3 µm at a varying percentage of eggshell powder (3 to 9%) in the stir zone. The thermal conductivity and coefficient of thermal expansion (CTE) were measured for the temperature range of 50 to 400 °C. In addition to it, differential thermal analysis (DTA), thermo-gravimetric analysis (TGA), and derivative thermo-gravimetric analysis (DTG) are conducted for the temperature range of 25 to 900 °C to discuss the endothermic, exothermic nature, and degradation characteristics. The result revealed the decreasing trend of thermal conductivity, and CTE values were found in the range of 97 to 53 W/mK and 26.6 to 24 × 10−6 K−1 (heating cycle), 27.2 to 23.8 × 10−6 K−1(cooling cycle), respectively. Furthermore, the higher and lower thermal conductivity of 108 W/mK and 62 W/mK is observed at higher and lower terminal voltages, 250 V and 100 V, respectively. The DTA, TGA, and DTG curves explored the maximum weight loss, which varies up to 5.25% with exothermic peaks and decomposition steps for each surface composite.

Case Study: Effect of mechanical short-circuiting of isolation pads on rooftop equipment noise and vibration transfer to spaces below.

The authors conducted investigations into noise from large rooftop air source heat pump (HP) equipment to student housing units below in a new concrete building. The investigation included both airborne noise and vibration measurements on the roof and in the dwelling units below. A total of five, 18-Ton devices were mounted on a foam-filled concrete housekeeping pad resting on an 8-inch thick PT structural slab and isolated by means of spring mounts fitted with neoprene isolation pads below their baseplate. The dwelling units below had exposed concrete at the ceiling, shear walls, and columns. Noise from the HPs were waking residents in the units directly below the equipment. After a number of adjustments to the spring isolation mounts to eliminate bindings and mechanical short-circuits, the investigation showed that vibration was also being transmitted to the building structure from the isolator base plates through the anchor bolts, bypassing the noise pads below the baseplate. Removal of this secondary short-circuit resulted in noticeable reductions in both noise and vibration at the spaces below, highlighting the need for careful adjustment and the provision of additional isolation elements in the installation.

Investigation of column-to-base connections of pole-mounted solar panel structures

This study investigated the load-carrying capacity of solar panel structures focusing on the column-to-base connection of pole-mounted structural systems using full-scale testing and numerical simulations considering the connection details as a key variable. The aim was to develop a non-welding connection detail for improved durability. For the connection details, a total of 10 plinths with base plates and supporting plate units were developed. The plinths with supporting plate units included two different bolt layouts at the column and base connections. The experimental results indicated that most specimens had sufficient load-carrying capacity to withstand the calculated yielding force even for the non-welding connections with supporting plate units. The failure modes observed in the experiments included cracking in the welded region, local buckling of the column, and bolt tear-out. The numerical simulations demonstrated that the details of the connection, such as the shape of the side plates, use of rib plates, and bolt layout, affected the structural performance. In addition, it was found that some specimens had strong and weak axes, depending on the orientation and shape of the side plates. Therefore, the details of the column–base connections of pole-mounted solar panel structures should be carefully designed based on proper structural evaluation of the connection details.

Non-uniform plastic deformation in additive friction stir deposited Ti-6Al-4V

Ti-6Al-4V (Ti-64) material deposited by additive friction stir deposition (AFSD) on a rolled Ti-64 base plate was evaluated. Extracted tensile coupons containing both base plate and AFSD regions showed different stress–strain responses in uniaxial tensile testing with digital image correlation. These differences were rationalized based on microstructure gradients observed by optical microscopy and spatially resolved laboratory X-ray powder diffraction (PXRD). The AFSD regions show characteristic basket weave α-Ti microstructure within the 25–50 μm prior β grains. The base plate shows a globular α+β microstructure typical of the rolled and annealed state. In one sample, plastic strain concentration occurred in the AFSD region where diffraction analysis indicates the 〈hki0〉α-Ti directions were preferentially loaded. In the second sample, strain concentration occurred in the rolled base plate, but the textured domains were smaller than the area probed by PXRD. The control of prior β microstructure using targeted deposition temperature and shear rate and axial stress will be critical to achieving rapid volumetric control for targeted final properties using AFSD with titanium alloys.

Component method applied to base plate connections of steel racks

This paper deals with the analytical prediction of the rotational strength and stiffness of base plate connections in steel storage racks under bending moment and axial compressive force. Based on the testing prescriptions of the European Code EN15512 and on the findings of an experimental campaign on 21 full scale specimens tested at four different values of constant axial force and under two different types of connection set-up, an analytical procedure relying on the component method is proposed to estimate the rotational strength and stiffness of all load bearing components, and, by suitable assembly of the contributing parts, to obtain a prediction of the overall strength and stiffness of the connection.The aim is to contribute to the definition of improved analytical tools of possible use in the design and product development stage or in the update of existing design codes.Quantitative results are, however, still mixed. Further investigations appear to be required for the stiffness, mainly to describe the nonlinear moment rotation curves observed in the experiments. Strength results are more accurate and as well successful in predicting the failure mode and the loss of strength with increasing compression.

Uncertain optimization for composite base plate of mortar under impact load

Information warfare places higher requirements on the remoteness, precision and mobility of artillery weapon systems. As an indispensable and important category of artillery, mortar plays an important role. As an important component of mortar, the base plate bears tremendous impact load. Its design level has an important influence on the shooting stability, shooting accuracy and maneuverability of the mortar. Composite base plate helps improve the maneuverability of the mortar, but it will also make the force and movement rule of mortar launching more complex and lead to a more acute contradiction between artillery power and maneuverability, which propose a huge challenge to modern artillery optimization design theory. Under this background, this manuscript conducts research on the structural uncertain optimization of composite material base plate for the mortar. In order to obtain the optimal solution and reasonable interval of uncertain parameters with main dimension parameters, this manuscript uses interval model to carry out deterministic transformation for uncertain objective function and uncertain constraints, combines multi-objective genetic algorithm to solve the problem, and carries out numerical simulation to verify the optimal value. The result shows that the design idea and method are feasible for uncertain optimization of composite base sheet of mortar under impact load, and the optimization objectives and strategies are effective, which can provide reference for the uncertain optimization research of composite base plate.

Design and Realization of Polymeric Waveguide/Microring Structures for Telecommunication Domain.

Polymer-based micro-optical components are very important for applications in optical communication. In this study, we theoretically investigated the coupling of polymeric waveguide and microring structures and experimentally demonstrated an efficient fabrication method to realize these structures on demand. First, the structures were designed and simulated using the FDTD method. The optical mode and loss in the coupling structures were calculated, thereby giving the optimal distance for optical mode coupling between two rib waveguide structures or for optical mode coupling in a microring resonance structure. Simulations results then guided us in the fabrication of the desired ring resonance microstructures using a robust and flexible direct laser writing technique. The entire optical system was thus designed and manufactured on a flat base plate so that it could be easily integrated in optical circuits.

An Investigation into Heat Transfer Enhancement by Using Oscillating Fins

The present work describes numerical and experimental investigation of the heat transfer characteristics in a plate-fin, having built-in piezoelectric actuator mounted on the base plate (substrate). The geometrical configuration considered in the present work is representative of a single element of the plate-fin and triple fins. Air is taken as the working fluid. A performance data for a single rectangular fin and triple fins are provided for different frequency levels (5, 30 and50HZ) , different input power (5,10,20,30,40 and 50W) and different inlet velocity (0.5, 1, 2, 3, 4, 5 and 6m/s) for the single rectangular fin and triple fins with and without oscillation. The investigation was also performed with different geometrical fin heights ( 50mm and 35mm) and distance between the fins (3mm and 6mm). It is observed that the heat transfer increases with the increase in the frequency and Reynolds number. It is further observed that triple fins with (height=50mm and distance between the fins=3mm) gives better enhancement as compared to othercases, The study shows that the piezoelectric actuator when mounted on the rectangular fins gives great promise for enhancing the heat transfer rate

Application of Lightweight Deflectometer to Assess Structural Competency of Nontraditional Airfield Pavements During Contingency Aircraft Operations

This paper discusses the use of the heavy and light weight deflectometer devices, hereafter referred to as HWD and LWD, respectively, to monitor the structural condition of airfield pavements during aircraft operations at contingency environments. Four airfield pavements like those encountered at contingency environments, referred to as nontraditional airfield pavements, were selected to conduct accelerated pavement traffic testing with simulated C-17 and C-130 aircraft. Pavement rut development was monitored, and both HWD and LWD tests were also conducted at selected traffic intervals. Both HWD and LWD were capable of tracking the pavement deterioration under accelerated traffic testing, which indicates that the LWD could be considered a potential rapid and practical pavement evaluation tool for nontraditional pavements during contingency aircraft operations. Based on current rutting failure threshold, a termination criterion in relation to a reduction in the stiffness parameter from the LWD test could be preliminarily used to aid in expediently determining acceptable aircraft operations on nontraditional airfield pavements. The influence of key operational parameters such as base plate dimension, the depth of influence from the impact force, and pavement rut formation must be further investigated to improve the effectiveness and applicability of the LWD test for nontraditional airfield pavements. The results from this study could be of interest to other low-volume road applications such as in agriculture, oilfield, large construction sites, and mining where pavement evaluation and management practices could be improved with the use of practical tools such as the LWD during the operations of heavy equipment or machinery.

Influence of oxygen content on melt pool dynamics in metal additive manufacturing: High-fidelity modeling with experimental validation

In the metal additive manufacturing process, the exposure to oxygen and its incorporation into the melt pool are usually deemed unfavorable, but cannot be completely eliminated. Yet, the understanding of this inevitable process remains limited. This work aims to shed light on the effect of oxygen content on melt pool dynamics through multiphysics thermal-fluid flow simulations of the laser powder bed fusion process. Our simulations reveal that oxygen sources from the powder, base plate and oxygen absorption from the atmosphere influences the melt pool dynamics. Although changes in oxygen content barely affect melt pool dimensions, they induce huge differences in the melt pool dynamics and the corresponding material composition distribution within the melt pool. Moreover, our model further clarifies and explains observed experimental phenomena. We demonstrate that the melt pool flow characteristics are responsible for the formation of oxygen-rich streaks observed in experiments regardless of inward or outward Marangoni circulation, while previous experimental studies attributed that to the outward circulation. Additionally, we show that sulfur content minimizes the effect of oxygen on Marangoni flow in iron alloys, and thus leads to the apparent consistency of surface roughness for additively manufactured iron alloys. This work is a fundamental development towards modeling for additive manufacturing under reactive atmospheres and provides unprecedented details on the effects of oxygen on melt pool dynamics. Consequently, this work can further offer practical guidance on powder reuse and adjusting manufacturing parameters for reused powders, thereby improving the sustainability of additive manufacturing.

A shake table investigation on low-cost seismic isolation using unbonded scrap tyre pad isolators

Seismic isolation is an effective strategy to mitigate the effect of earthquake on structures. Conventional seismic isolation is still inaccessible to developing countries as it is expensive. Scrap tyres have been identified to be suitable for use as base isolators. It is also a challenge to recycle, reuse and effectively dispose this rapidly accumulating waste material without harming the environment as it is heavy, thick and made up of multiple materials. In this paper, the effectiveness of using scrap tyre pads for base isolation is investigated. Scrap tyres of size 175/65/R14 are considered in the study. The tread portion of the scrap tyre is cut into pads of definite size and shape and arranged one above the other to form the isolator. The scrap tyre pads which contain both rubber and intervening steel cords make it vertically stiff and laterally flexible which will in turn reduce the cost of the system as they do not require additional materials for enhancing the stiffness properties. The application without steel end plates further reduces the cost and hence suitable as a low-cost seismic protection system for developing countries. In the present study square shaped unbonded scrap tyre pad isolators of three configurations using 4, 6 and 8 layers of scrap tyre pads are considered. Initially, the dynamic horizontal stiffness of different configurations of scrap tyre pad isolators is estimated using a shake table test on a system consisting of a set of rectangular plates supported by 4 isolators at the corners of the base plate. A shake table test is also conducted on a three storied scaled building frame model supported on four isolators at the four corners of the base of the model. All the isolators are found to be effective in shifting the fundamental time period of the frame. Finite element analysis on isolators with 4, 6, 8 and 10 layers are also carried out to determine the effect of vertical pressure on the fundamental frequency and dynamic stiffness of isolator systems.

Review on Design Fixtures for Wheel House of Car

Abstract: A fixture is a work-holding device used in the manufacturing industry. Fixture’s primary purpose is to create a secure mounting point for a work piece, allowing for support during operation and increased accuracy, precision, reliability, and interchange ability in the finished parts. This paper present Review on Design of fixture for wheel house of car. This component is a part of Four wheeler Car. The operation to be performed is Spot welding. The evaluated fixture uses Mylar, Riser, Clamp arm ,Plate, Base plate, welding part used for work support for holding the work piece driven by Pneumatic Air. This is Multipale used new fixture achieves automatic clamping of parts in same fixture.

Magnetic fabric analyses of basin inversion: a sandbox modelling approach

Abstract. A magnetic fabric analysis is a useful tool to display deformation in nature and in models. In this study, three sandbox models represent basin inversion above a velocity discontinuity (base plate). After complete deformation of each model, samples were taken in different parts of the models (along faults and areas away from faults) for magnetic fabric analysis. Model I, which simulates basin formation during extension, shows two kinds of magnetic fabric: an “undeformed”/initial fabric in areas away from faults and a normal fault-induced fabric with a magnetic foliation that tends to align with the fault surface. Models II and III were extended to the same stage as Model I but were subsequently shortened/inverted by 1.5 cm (Model II) and 4 cm (Model III). Both inverted models developed “thrusts” during inversion. The thrusts show an alignment of magnetic foliation parallel to the fault surfaces that depends on the maturity of the thrust. Our results highlight that thrusting is more efficient in aligning the magnetic fabric along them compared to normal faults. Moreover, models II and III reveal a magnetic fabric overprint towards a penetrative strain-induced fabric (magnetic lineation perpendicular to shortening direction) with increasing strain in areas away from thrusts. Such overprint shows a gradual transition of a magnetic fabric to a penetrative strain-induced fabric and further into a thrust-induced fabric during shortening/inversion. In contrast, extension (Model I) developed distinct magnetic fabrics without gradual overprint. In addition, pre-existing normal faults are also overprinted to a penetrative strain-induced fabric during model inversion. They define weak zones within the main pop-up imbricate and steepen during model inversion. Steepening influences the magnetic fabric at the faults and, in general, the strain propagation through the model during inversion. The magnetic fabric extracted from the models presented here reflect the different stages of basin development and inversion. This study is a first attempt of applying magnetic fabric analyses on models simulating inverted basins. This study illustrates the possibility of applying a robust tool, i.e. magnetic fabric analyses, to sandbox models, whose initial, intermediate, and final stages are well documented, to understand fabric development in inverted tectonic regimes.

Test program on stiffened column bases subjected to cyclic loading

This article presents the recorded data from an experimental campaign on stiffened steel column bases. The connection configuration comprises an exposed base plate on which vertical stiffeners are welded to strengthen the assembly. Using stiffened column bases is common in several countries where providing thick steel plates is not practical. However, despite their broad application in existing steel structures, there was rare experimental data collected exclusively on their hysteresis response to seismic excitations. The designed testing program intends to document the connection behavior under cyclic loading. This article describes the data collection process, including specimen geometry, material properties, construction details, test setup, instrumentation, and loading history. The qualitative observations are reported to support the data application, and the recorded data set is deposited publicly for future use (DOI: 10.5281/zenodo.7058873).

3D response simulation of a bridge with a posttensioned base rocking steel pier under sequential loading of traffic loads, braking force, and earthquake excitations

AbstractThis paper presents finite element (FE) investigations of the seismic response of a bridge incorporating a base rocking steel pier. The pier consists of a circular steel tube, circular end plates, posttensioned (PT) tendon(s), and supplemental energy dissipation devices, and is configured to rock at its interface with the foundation. The main characteristic of such a pier is its ability to ensure small residual drifts after undergoing inelastic deformations during cyclic loading. The system has a tendency to close the gap due to the presence of superstructure dead load (DL) and tendon posttensioning force. Using experimental data, the calibration of the FE procedure is done at the material, component, and global system levels. The FE model of a prototype bridge is developed with the rocking pier modelled by continuum elements while superstructure, bearing units, abutment walls and backfill material modelled by discrete elements. The analysis procedure includes the application of one or two earthquake excitations, traffic loads, and braking force. The varied parameters are the diameter‐to‐thickness ratio of the column, presence of a PT tendon, addition of supplemental energy dissipaters (EDs), base plate dimensions, height of ED chairs, and ED strength. The results of dynamic FE studies demonstrate that a bridge utilizing such a pier has the potential to undergo consecutive earthquakes without sustaining significant damage and return to its original position without requiring abutment component stiffness and strength.