Load-deflection Characteristics Research Articles

Development of a rolling truck tyre model using an automatic model regeneration algorithm

A three-dimensional finite element model of a rolling radial-ply truck tyre is developed to predict its vertical and cornering properties at relatively high speeds. The model includes a detailed representation of the tyre complex geometry and multi-layered composite structure including the carcass and belt plies, bead fillers and tread. LS-DYNA, a nonlinear finite element code, is used as the simulation tool. An algorithm is developed for efficient formulation of the model for parametric analyses. The validity of the proposed tyre model is demonstrated by comparing the predicted load-deflection, cornering and free vertical vibration characteristics with the reported experimental data. The simulation results revealed robust behaviour of the tyre model up to rolling speeds of 100 km/h. The verified tyre model is subsequently employed to study the influences of various operating parameters, namely, the inflation pressure, vertical load, rolling speed and road friction on the tyre vertical and cornering properties.

Development of a rolling truck tyre model using an automatic model regeneration algorithm

A three-dimensional finite element model of a rolling radial-ply truck tyre is developed to predict its vertical and cornering properties at relatively high speeds. The model includes a detailed representation of the tyre complex geometry and multi-layered composite structure including the carcass and belt plies, bead fillers and tread. LS-DYNA, a nonlinear finite element code, is used as the simulation tool. An algorithm is developed for efficient formulation of the model for parametric analyses. The validity of the proposed tyre model is demonstrated by comparing the predicted load-deflection, cornering and free vertical vibration characteristics with the reported experimental data. The simulation results revealed robust behaviour of the tyre model up to rolling speeds of 100 km/h. The verified tyre model is subsequently employed to study the influences of various operating parameters, namely, the inflation pressure, vertical load, rolling speed and road friction on the tyre vertical and cornering properties.

Analysis of the Force during Overcoming the Roadblock – The Preliminary Experimental Tests

Summary. The paper applies to the issue of preservation of passenger vehicles during overcoming the roadblocks on a dry asphalt surface with the constant speed. The study aimed to estimate the forces which are affecting the suspension of the vehicle during the contact between a tyre and roadblock. Using the video recording it is possible to calculate the values of the tyre deflection and forces acting in the system. The obtained deflections of the tyres were compared to earlier laboratory test results and loaddeflection characteristics of the tyres with the same size. The roadblock with the defined geometry causes a dynamic deflection of the tyre. During the study a significant change in the geometry of the suspension has not occurred. The paper presents the characteristics of the vehicles research with a particular regard to model and type of tyres. The determination of the exact dimensions of the roadblocks and application of the ADIS 16385 system for acquisition and archiving the features of the kinematic motion of the vehicle allowed to determine the speed at the moment of collision with the roadblock.

Comparison of the Load-Deflection Characteristics of Aesthetic and Conventional Super Elastic Ni-Ti Orthodontic Arch Wires in Conventional and Metal-Insert Ceramic Brackets.

Coated arch wires and ceramic brackets have been introduced to improve aesthetics during orthodontic treatment. The aim of this study was to determine the effects of coating on the physical properties of aesthetic orthodontic wires. Five round wires (0.016 inch) were obtained from each of three brands: conventional uncoated super elastic Nickel Titanium (Ni-Ti) (Rematitian Lite; Dentaurum, Ispringen, Germany), HUBIT (Teflon Coated, Korea), G&H (Epoxy Coated, Greenwood, Indiana, USA) which belonged to maxillary arch. Two types of standard ceramic brackets (conventional and metal-insert type, Ortho Technology, Tampa, Florida, USA) with the slot size of 0.022×0.028 inches were used. A simulation device was fabricated to resemble a model of human dental arch and each of the specimen was tested in three-point bending test. The test was conducted in the buccolingual plane with crosshead speed of 1mm/minute pressure from metal pole. Each sample was loaded until a deflection of 3.0 mm was produced. The mean values of maximum loading force, unloading force and clinical plateau length were recorded. One-way ANOVA and Tukey tests were used at p<0.05. Uncoated Ni-Ti arch wire showed higher mean values of maximum loading and unloading force than that of coated aesthetic wires similar to ceramic brackets while G&H wire and metal-insert ceramic brackets presented the lowest values. The longest clinical plateau length was observed in G&H wires and metal-insert ceramic bracket. The coating processes for HUBIT (Teflon Coated, Korea), G&H (Epoxy Coated, Greenwood, Indiana, USA) wires might influence bending behaviour which can cause decrease in loading and unloading force.

Racking shear resistance of steel frames with corner connected precast concrete infill panels

When precast concrete infill panels are connected to steel frames at discrete locations, interaction at the structural interface is neither complete nor absent. The contribution of precast concrete infill panels to the lateral stiffness and strength of steel frames can be significant depending on the quality, quantity and location of the discrete interface connections. This paper presents preliminary experimental and finite element results of an investigation into the composite behaviour of a square steel frame with a precast concrete infill panel subject to lateral loading. The panel is connected at the corners to the ends of the top and bottom beams. The Frame-to-Panel-Connection, FPC4 between steel beam and concrete panel consists of two parts. A T-section with five achor bars welded to the top of the flange is cast in at the panel corner at a forty five degree angle. The triangularly shaped web of the T-section is reinforced against local buckling with a stiffener plate. The second part consists of a triangular gusset plate which is welded to the beam flange. Two bolts acting in shear connect the gusset plate to the web of the T-section. This way the connection can act in tension or compression. Experimental pull-out tests on individual connections allowed their load deflection characteristics to be established. A full scale experiment was performed on a one-storey one-bay 3 by 3 m infilled frame structure which was horizontally loaded at the top. With the characteristics of the frame-to-panel connections obtained from the experiments on individual connections, finite element analyses were performed on the infilled frame structures taking geometric and material non-linear behaviour of the structural components into account. The finite element model yields reasonably accurate results. This allows the model to be used for further parametric studies.

An Optimized Elasto-Plastic Subgrade Reaction For Modeling The Response Of A Nonlinear Foundation For A Structural Analysis

Abstract Geotechnical and structural engineers are faced with a difficult task when their designs interact with each other. For complex projects, this is more the norm than the exception. In order to help bridge that gap, a method for modeling the behavior of a foundation using a simple elasto-plastic subgrade reaction was developed. The method uses an optimization technique to position 4-6 springs along a pile foundation to produce similar load deflection characteristics that were modeled by more sophisticated geotechnical finite element software. The methodology uses an Excel spreadsheet for accepting user input and delivering an optimized subgrade spring stiffness, yield, and position along the pile. In this way, the behavior developed from the geotechnical software can be transferred to the structural analysis software. The optimization is achieved through the solver add-in within Excel. Additionally, a beam on a nonlinear elastic foundation model is used to compute deflections of the optimized subgrade reaction configuration.

Structural behaviour of bamboo-reinforced foamed concrete slab containing polyvinyl wastes (PW) as partial replacement of fine aggregate

This paper reports the findings of experimental study to investigate the structural behaviour of bamboo-reinforced foamed concrete slab with polyvinyl waste as partial replacement of fine aggregates. The structural properties studied were: compressive strength, density, crack development pattern and propagation, failure pattern, load–deflection characteristics and the ultimate moment. Compressive strength and the density tests were also conducted using 150×150×150 cube specimens. The flexural behaviour was investigated by using 1300×500×100mm slab specimens. The results showed that: (i) partial replacement of sand with polyvinyl waste (PW) improved the compressive strength of the foamed aerated concrete specimens, (ii) that slab specimens with polyvinyl waste as partial replacement sand exhibited shear bending failure, (iii) all the slab specimens with polyvinyl waste as partial replacement sand recorded lower values of deflection for the same loading, as the level of sand replacement with polyvinyl wastes increased, and (iv) increase in the amount of sand replaced with polyvinyl wastes resulted in improved bending performance of the slab specimens.

Fabrication and Characterization of Biocomposite Using Grewia Optiva Fibre (i.e. Bhimal) Reinforced Polyvinyl Alcohol (PVA)

Bhimal fibres are quite a newer kind of bio-degradable fibres. They have never been heard before in literatures from the view point of their utility as engineering material. These fibres have been utilized for investigation of their properties. Characterization of this fibre is essential to determine its properties for further use as reinforcing fibre in polymeric, bio-degradable and other kinds of matrix. With this objective, the fabrication method and other mechanical properties of Bhimal-reinforced-PVA biocomposite have been discussed. The stress-strain curves and load-deflection characteristics are obtained. The tensile, compressive, flexure and impact strengths have been calculated. The results are shown in tables and graphs. The results obtained are compared with other existing natural fibre biocomposites. From the observations, it has been concluded that the tensile strength of Bhimal-reinforced-PVA biocomposite is higher than other natural fibre composites. Hence these can be used as reinforcement to produce much lighter weight biocomposites.

Load Deflection Characteristics of Sustainable Infilled Concrete Wall Panels

Development of sustainable concrete has now become a mandatory requirement today due to environmental problems posed by the production of conventional concrete. Many researchers focused their research toward finding alternate materials for cement, sand, steel, etc., and came out with good results. This paper focuses on feasibility of developing sustainable concrete using bamboo as infill, stiffener, and combination of infill and reinforcement in the wall panels. In addition, low-density polyethylene waste also tried as infill material with bamboo as diagonal member. The structural property of bamboo was studied for replacing the conventional steel by designing the wall panels with lower stiffness and weight to avoid the catastrophic effect. The strength and behavior of infill wall panels for different infill cases were studied under uniaxial in-plane loading. Parameters such as maximum load carrying capacity, load–deflection characteristics, and cost effectiveness of bamboo-based wall panel system were considered in the present study. From the experimental results, it was understood that bamboo-based wall panel behaved as a ductile member and failed after due to the formation of micro-cracks. Wall panel specimens were failed with an out-plan buckling and resisted the force such that the sudden collapse was avoided. It was concluded that an infill wall reduced lateral and vertical deflection, thereby decreasing the probability of collapse. Hence, an infill wall panel could be used as a substitute for conventional wall panel.

A general third-order theory of functionally graded plates with modified couple stress effect and the von Kármán nonlinearity: theory and finite element analysis

Finite element analysis of functionally graded plates based on a general third-order shear deformation plate theory with a modified couple stress effect and the von Karman nonlinearity is carried out to bring out the effects of couple stress, geometric nonlinearity and power-law variation of the material composition through the plate thickness on the bending deflections of plates. The theory requires no shear correction factors. The principle of virtual displacements is utilized to develop a nonlinear finite element model. The finite element model requires C1 continuity of all dependent variables. The microstructural effects are captured using a length scale parameter via the modified couple stress theory. The variation of two-constituent material is assumed through the thickness direction according to a power-law distribution. Numerical results are presented for static bending problems of rectangular plates with various boundary conditions to bring out the parametric effects of the power-law index and length scale parameter on the load–deflection characteristics of plates with various boundary conditions.

Influence of Reinforcement Ratio on Flexural Behavior of Prestressed UHPCC Beam

Using experimental study, major emphasis of the present study is to determine the influence of reinforcement ratio on structural behavior of the prestressed beams made of UHPCC in terms of first crack load, peak load, ductility, and load-deflection characteristics. A UHPCC mixing proportion was presented firstly. 8 rectangular beams of size 100x300x3000mm made of UHPCC were designed, fabricated and tested in this investigation. Influence of reinforcement ratio of load bearing capacity, deflection and crack pattern of beams were performed and analyzed. Based on experimental results, some conclusions were drawn.

Load-deflection characteristics and force levels of coated nickel titanium orthodontic archwires

Background: Coated archwires have been introduced to improve esthetics during orthodontic treatment. Theaim of the present study was to evaluate and compare the load–deflection characteristics and force levels of six brands of coated nickel titanium orthodontic archwires using palatal and gingival deflection. Materials and methods: Ten round wires (0.016 inch) and ten rectangular wires (0.019x0.025 inch) were obtained from each of six brands (G&H, Opal, Ortho Technology, Dany, Hubit and Astar Companies). The load-deflection properties of these archwires were evaluated by the modified bending test usinga readymade dental arch model in both palatal and gingival directions at 37°C temperature using a universal material testing machine. Forces generated at maximum loading of 2mm and at unloading of 1.5mm were measured. Results: All the wires showed hysteresis and significant differences in their load deflection curves, but these differences were more evident in round wires than in rectangular wires where G&H wires showed the widest loading- unloading deflection curves. The maximum loading force of round wires in gingival deflection were higher than by palatal deflection. The force decline during unloading (plateau gap) ranged between 18 to 34% for round wires and 17 to 37% for rectangular wires. Conclusion: Coated epoxy wires (G&H, Opal, Astar and Ortho Technology) produced lower forces compared to polymer (Dany) and Teflon (Hubit) coated round and rectangular archwire.

An in vitro assessment of the mechanical characteristics of nickel-titanium orthodontic wires in Fluoride solutions with different acidities.

Objectives:The aim was to evaluate the in vitro effects of fluoride solutions with different acidities on load-deflection characteristics of nickel-titanium (NiTi) orthodontic wires.Materials and Methods:In this study, which lasted 30 days, 36 (3 cm long, 0.016 × 0.022 inches, SENT 1622, G & H wire Company, Greenwood, Indiana, USA) NiTi wires, were divided into three experimental groups of 12 each. Two groups were subjected to 0.05 topical fluoride mouthwash with different acidities (G1, pH 4; G2, pH 6.6) for 90 s, twice a day, and kept in normal saline after that. The third group (G3, the control group) was kept in normal saline only. Load and unload forces were measured with three bracket bending test in a universal testing machine (Testometric Co, Rochdale, UK). Loading and unloading plateaus and hysteresis were also recorded. Data were then analyzed using analysis of variance and honestly significant difference Tukey at P < 0.05.Results:During the loading phase, there was a significant difference between deflections (P < 0.001); but there was no interaction effect (P = 0.191) and no significant difference among three groups (P = 0.268). In the unloading phase, there was a significant difference between deflections (P < 0.001) and an interaction effect was also observed (P = 0.008). Further, significant differences noted among three groups (P = 0.037). Only in the unloading phase, at deflections of 2.2 through 0.2 mm, significant differences between the mean force values of the G1 and G3 groups were observed (P = 0.037).Conclusion:Based on this in-vitro study, compared to neutral fluoride solution, daily mouthwash with a fluoride solution with more acidic pH of 4 affected the NiTi wires load-deflection characteristics during the unloading phase. This finding may have clinical implications and can be further validated by in-vivo studies.

Effect of Temperature on Deactivation Force of Three Commercial NiTi Orthodontic Archwires

Objective: The purpose of this study was to investigate the transition temperature range (TTR) and the effect of temperatures at 10, 20, 30, 40, 50 and 60 °C on the deactivation force of three commercially available NiTi archwires. Materials and methods: Three different brands of NiTi archwires, NiTi OR (Ormco), NiTi GH (G&amp;H) and NiTi H (Highland), with a cross sectional area of 0.016 x 0.022 inch2 were analysed for transformation temperature range (TTR) by using differential scanning calorimeter and load-deflection characteristics using a three-point bending test at temperatures of 10, 20, 30, 37, 40, 50 and 60 °C. Statistical Analysis: Descriptive analysis was used to calculate each variable and Kruskal Wallis test was performed to assess the difference in measurements among the three NiTi wires. P&lt;0.05 was considered as statistical significant. Results: TTR showed austenitic temperature finish (Af) at 24.45 °C for NiTi OR, 27.55 °C for NiTi GH and 51.5 °C for NiTi H. The highest deactivation force was found in NiTi H followed by NiTi OR and NiTi GH at the temperatures below and higher than 37°C. There were siginificant differences (p&lt;0.05) in the deactivation force of NiTi OR - NiTi H and NiTi GH - NiTi H at 10 °C and 20 oC, and NiTi GH – NiTi H and NiTi GH – NiTi OR at 30 °C and 37 °C. However, no significant difference was found among all NiTi wires at 40, 50 and 60 oC, except NiTi GH – NiTi H at 60 oC. A close relationship was found between temperature and unloading curves (deactivaton force); increase in the temperature led to an increase in the plateau of delivery deactivation force and decrease in temperature led to a decrease in the plateau of delivery deactivation force. Conclusion: The TTRs of commercial NiTi archwires are variable, expecially the austenitic finish temperature. The deactivation force increases in higher temperature and decreases in lower temperature.

An experimental investigation on flexural behavior of RC beams strengthened with different techniques

In in many earthquake-prone regions and countries including Mediterranean area, India, the Middle East, Southeast Asia, existing buildings with its structural elements such as Reinforced Concrete (RC) beams and columns, which show little ductility, have consistently exhibited poor performance during past earthquakes and consequently unavoidable earthquake damages on these structures led to a significant loss of world cultural heritage. Therefore, appropriate strengthening techniques have to be implemented in order to improve load carrying capacities and overall ductility. This paper summarizes experimental investigations of damaged and undamaged RC beams. In this context, twenty-seven beams were tested under combined bending and shear. Eighteen RC beams were damaged and then strengthened with four different methods while nine were kept undamaged. The behavior of damaged and undamaged RC beams is discussed with emphasis on the load deflection and strain characteristics. The results indicate that the specimens strengthened with full jacketing had slightly higher load carrying capacity than the reference beams strengthened with other techniques. The experimental results can also be used for understanding the most convenient strengthened technique for damaged beams.

Theory of un-scaled flexibility identification from output-only data

The magnitudes of the frequency response functions (FRFs) from ambient vibrations are seldom to be investigated because they are not necessary for basic modal parameter (frequency, damping and mode shape) identification. However, they are necessary for structural flexibility identification. In this article, the FRF magnitudes from output-only data are investigated, and an approach to identify structural un-scaled flexibility characteristics is proposed. It first quantitatively formulates the relation between the magnitudes of the FRFs estimated from the vibration test data with known/unknown input forces. It is proved that the magnitude ratios between the above two kinds of FRFs are mode-dependent. Then, a way to calculate the magnitude ratios is proposed to scale the FRFs from output-only data. Finally, the closed-form solution of the un-scaled flexibility is derived from ambient vibration data. The identified un-scaled flexibility will reveal the load–deflection characteristics of a structure to further engineers׳ understanding about the structure׳s safety condition. Numerical and experimental examples illustrate the effectiveness of the un-scaled flexibility identification theory.

Evaluation of stress softening of the rubber suspension used on rail vehicles

In the rail industry, the important design parameters of rubber suspension systems are currently solely based on the loading part of the loading/unloading history, e.g. the load–deflection characteristics and fatigue requirement. Different energy levels and stress values are created for an identical load value during loading and unloading cycles in rubber-like materials. Hence, the performance of a rubber suspension can be substantially different during loading and unloading, which can lead to unexpected effects. An engineering approach is proposed to account for this so-called Mullins effect. Existing elastomeric models, widely used in rail vehicle design, can be modified to account for the unloading using this methodology. A typical rubber-to-metal bonded component, which is used in rail suspension systems, is selected for a verification study. It is shown that the predictions from the new approach are consistent with the results of the whole load/deflection history obtained in a laboratory experiment. In addition, if the unloading characteristics are not considered, results obtained from stress calculations can have a 20% margin of error. The proposed approach should be further verified using other types of rubber suspension systems.

1203 鉄道車両用腰掛の座り心地とクッション硬さの関連性に関する研究(OS1-1 鉄道の振動・乗り心地と車体,OS1 交通・物流システムの高速化,利便性,快適性の向上,オーガナイズド・セッション(OS))

In this study, it was intended to grasp quantitatively relationship between load-deflection characteristics and comfort in the cushion of railway vehicle seat. Therefore, sensory evaluation test of comfort was subjected by using several kinds of cushion that load-deflection characteristics are different but shapes are same. As a result, it was found that there is relationship to load-deflection characteristics and comfort of cushion, and it is desirable for determination of hardness of the cushion to be based on a feeling of hardness.

Experimental and Analytical Investigations on Flexural Behaviour of Retrofitted Reinforced Concrete Beams with Geopolymer Concrete Composites

Existing multi-storey buildings in earthquake prone regions of India are vulnerable to severe damage under earthquakes. So there is an urgent need for retrofitting of deficient and damaged buildings. Portland cement (PC) production is under critical review due to high amount of carbon dioxide gas released to the atmosphere and Portland cement is also one among the most energy-intensive construction material. The current contribution of greenhouse gas emission from Portland cement production is about 1.5 billion tons annually or about 7% of the total greenhouse gas emissions to the earth’s atmosphere. So retrofitting of existing deficient building using eco-friendly material which could promise higher structural performance than the original building is essential.Geopolymer concrete (GPC) is a non-Portland cement binder based on alkaline activation of industrial wastes such as fly ash and GGBS. The application Geopolymer concrete in retrofitting can reduce the production of cement and can create an ecofriendly construction atmosphere to an extent. So the feasibility of geopolymer concrete in retrofitting of damaged structures is required to be studied. This paper presents the details of the mix designs of GPC mixes, preparation of retrofitted test specimen, testing and evaluation with respect to cracking, ultimate load, deflection and failure modes. Non-linear finite element analysis of beams by 3D modeling of concrete (solid 65 element) and discrete modeling of reinforcement (Link 8 element) was carried out using ANSYS software. The load deflection characteristics, failure modes and crack patterns are obtained from the experimental and analytical studies. The results of the study indicate that the performance of retrofitted beam with GPC and control beam shows good agreement in ultimate load, failure modes and crack patterns.

Plastic Buckling of Metallic and Nonmetallic Thin-Walled Tubes under Static Axial Compression

An experimental study for series of tests were conducted on stainless steel 304 and polyvinylchloride circular tubes loaded statically and axially at room temperature. The specimens tested with same variation of slenderness ratio for both materials with constant axial length. Load-deflection characteristics for stainless steel 304 and polyvinylchloride circular tubes specimens and the influence of plastic properties and collapsing load were illustrated .The experimental results are compared with other experimental published and give good agreement. It is showed that the values of initial peak load ,yield end load and plastic work increase with increasing slenderness ratio at constant length. Also it is observed that the collapse modes are different for both materials.