Faramarz Gordaninejad | University Of Nevada Reno (original) (raw)

Papers by Faramarz Gordaninejad

Proceedings of SPIE, Jul 31, 2003

Theoretical and experimental studies are performed for the design, development and testing of a n... more Theoretical and experimental studies are performed for the design, development and testing of a new fail-safe semiactive magneto-rheological fluid (MRF) damper for a high-mobility multi-purpose wheeled vehicle (HMMWV). A fail-safe MRF damper is referred to as a device, which retains a minimum damping capacity required in the event of a power supply or electronic system failure. The proposed MRF damper

Proceedings of SPIE, Apr 3, 2015

A magnetorheological elastomer (MRE)-based wireless sensor is designed, developed and tested, whi... more A magnetorheological elastomer (MRE)-based wireless sensor is designed, developed and tested, which is capable of sensing compression and shear forces. The MRE wireless sensor system consists of a disk-shape MRE sample with two thin steel electrodes attached to both sides and two wires connected to electrodes. Electrical resistance of MRE sensor samples changes due to piezoresistance behavior of MRE as various axial and shear stresses are applied. Electrical resistance decreases as the applied compressive axial forces increases, on the other hand, the electrical resistance increases as the applied shear force increases. Different MRE sensor configurations are evaluated for design optimization.

Journal of Intelligent Material Systems and Structures, Sep 1, 1998

One method of achieving fail-safe, semi-active damping is to utilize a controllable fluid with a ... more One method of achieving fail-safe, semi-active damping is to utilize a controllable fluid with a high zero-field damping capacity. To this end, this paper introduces a prototype electrorheological grease (ERG) as a new concept in electro-rheological fluids (ERF's). The general properties of grease-like fluids imply a non-Newtonian post yield viscosity. The fluid model developed in this paper considers the influence of a non-Newtonian post yield viscosity by using a power law model to account for shear thinning behavior. This model can be applied to all controllable fluids since it reduces to a Newtonian viscosity as a special case. The theoretical study includes a lumped parameter dynamic system model to predict the behavior of an actual damper, which takes into consideration inertial and compressibility effects. To validate the proposed models, a prototype damper was designed and used to collect data for a known ERF and the new ERG. Results from the ERG test data indicate that a good match between experimental and theoretical data was achieved. A sensitivity analysis shows that the model was insensitive to the mass of the fluid, but sensitive to the bulk modulus of the fluid. Comparisons are also made between the performance of the ERG and the existing ERF. The ERG demonstrates higher zero-electric field damping capacities than those of the ERF, yet produces an increase in damping when an electric field is applied.

Connections are the key to a good structural system. This paper describes an experimental/analyti... more Connections are the key to a good structural system. This paper describes an experimental/analytical project that studied the behavior of beam-to-column connections constructed from FRP composites that were only connected with structural epoxy adhesive. Two beam-column connection specimens were constructed from I-shaped sections. The connection in the second test was altered based on the results from the first test. Three-dimensional finite element models were used to predict the failure of the specimens during testing. Through connection improvements, the failure load of the second specimen was approximately double that of the first specimen, but still below the capacity of the beam and column. The use of shapes close to that of structural steel, while convenient, does not utilize the strength nor hide the weaknesses of the advanced composite materials used.

Structural Engineering in Natural Hazards Mitigation, 1993

An experimental and analytical study of six graphite composite beams are presented. Four of the b... more An experimental and analytical study of six graphite composite beams are presented. Four of the beams incorporated a reinforced concrete slab. The composite action and the effect of concrete strength were studied. The results showed that it may be feasible to use this type of beams in bridge engineering.

International Journal of Modern Physics B, Oct 30, 1996

Theoretical and experimental scale analyses are conducted to investigate the effects of length of... more Theoretical and experimental scale analyses are conducted to investigate the effects of length of the damper and electric field strength on the damping and stiffness coefficients of electrorheological fluid (ERF) dampers. It is demonstrated that by employing the results obtained from smaller size prototypes, the energy absorbing capacity of larger dampers can be estimated.

Journal of Structural Engineering-asce, Feb 1, 2010

ABSTRACT

WORLD SCIENTIFIC eBooks, 2007

CRC Press eBooks, Jul 1, 2008

A novel magnetorheological fluid, in which the surface of iron particles is coated with poly (but... more A novel magnetorheological fluid, in which the surface of iron particles is coated with poly (butyl acrylate) by surface initiated atom transfer radical polymerization (ATRP), is investigated. The polymer coating procedure includes two steps, which are immobilization of initiator: 2-4(- ...

The Royal Society of Chemistry eBooks, Oct 31, 2007

Magnetorheological (MR) and electrorheological (ER) fluids are suspensions of magnetisable or pol... more Magnetorheological (MR) and electrorheological (ER) fluids are suspensions of magnetisable or polarisable micrometre-size particles in a base liquid. Both fluids are controllable since their rheological properties change dramatically, reversibly and repeatedly in response to an applied magnetic or e...

In this study, the performance of a new design concept utilizing a magnetorheological (MR) fluid ... more In this study, the performance of a new design concept utilizing a magnetorheological (MR) fluid composite material is examined through encapsulating a MR fluid into an elastomer. A prototype of MR fluid-elastomer vibration isolator is built and its dynamic behavior is studied in oscillatory compressions for a wide range of frequencies under various input electric currents. The experimental results show that both the stiffness and the damping capability of the MR fluidelastomer vibration isolator is a function of the displacement amplitude and magnetic field strength, and only weakly dependent upon the frequency of excitation; unlike the squeeze film mode counterparts [1]. This demonstrates that the new vibration isolator, whose mechanical properties can be controlled by an applied magnetic field, has potential in applications where tuning vibration characteristics are desired.

Electrorheological Fluids and Magnetorheological Suspensions, Jun 1, 2000

International Journal for Numerical Methods in Engineering, Mar 1, 1984

A transfer-matrix analysis is presented for determining the static behaviour of thick beams of 'm... more A transfer-matrix analysis is presented for determining the static behaviour of thick beams of 'multimodular materials' (i.e. materials which have different elastic behaviour in tension and compression, with nonlinear stress-strain curves approximated as piecewise linear, with four or more segments). To validate the transfer-matrix method results, a closed-form solution is also presented for cases in which the neutral-surface location is constant along the beam axis. Numerical results for axial displacement, transverse deflection, bending slope, bending moment, transverse shear, axial force and location of neutral surface are presented for multimodular and bimodular models of unidirectional aramid cordrubber. The transfer-matrix method results agree very well with the closed-form solutions.

An innovative concept was explored in this work, wherein steel reinforcement was used to provide ... more An innovative concept was explored in this work, wherein steel reinforcement was used to provide ductility capacity and to control the failure mode, and carbon fiber was used to provide shear reinforcement, confinement, and longitudinal reinforcement where elastic behavior is needed. In addition, hinge zones were relocated away from member ends to ensure that damage can be limited and controlled entirely within plastic hinge zones which are specially detailed, while all other portions of the structure remain essentially elastic at all times. The main aim of the study was to determine if a conventional civil engineering material such as reinforced concrete would work with an advanced composite material such as carbon fiber to provide an alternative to bridge substructure construction or major rehabilitation. Experimental and analytical results are presented in addition to a discussion of future applications of these sections.

This document presents the development and experimental validation of seismic retrofitting of non... more This document presents the development and experimental validation of seismic retrofitting of non-prismatic (flared) reinforced concrete bridge columns. Fiber reinforced plastic (FRP) jacketing was installed on the non-prismatic columns to enhance the shear capacity and improve the seismic response of the columns. Two .03-scale columns, one encased with a glass fiber-epoxy and the other with a carbon fiber-epoxy fabric were tested. A shake table was used to load the column with a strong motion accelerogram from the 1994 Northridge earthquake. The measured results were compared to those from testing of an as-built and steel-jacketed specimen to evaluate the effectiveness of the retrofit methods. The FRP jacket design and installation methods, as well as shear capacity calculation are presented. The experimental data indicated that both FRP jackets significantly improved the shear capacity and ductility. The performance of the columns retrofitted with FRP was very similar to that of a steel-jacketed column.

Report No. CCEER-92-2This research presents the analytical and experimental study of the basic be... more Report No. CCEER-92-2This research presents the analytical and experimental study of the basic behavior of composite sections made of concrete slabs and graphite/epoxy beams. The study also includes the testing of bond between concrete and graphite/epoxy plates connected by a structural epoxy adhesive. Five bond specimens were built and tested. The bond test results indicate that, by using an appropriate type of epoxy adhesives, it is possible to develop large interface stresses between the concrete and the graphite/epoxy. Two groups of beam specimens were tested and analyzed. Each group consisted of three specimens of the same graphite/epoxy cross section. The cross section used in the first group was of a wide flange beam made of symmetrically laminated graphite/epoxy composite. The cross section of the other group was of a double box beam made of non-symmetric laminates. In each group, one reference beam was tested without a concrete slab, while the other two were fitted with concrete slabs to represent bridge decks built to about one-eighth scale. Comparisons between the data collected from the tests and the results obtained from the analytical model indicate that it is possible to accurately predict the static response and the failure load of concrete and graphite/epoxy composite sections (Abstract by authors)

Amplitude-scaled to minimize the sum of the squared error over a period range T H = 1.5-4.0 sec a... more Amplitude-scaled to minimize the sum of the squared error over a period range T H = 1.5-4.0 sec and T V = 0-2.0 sec. 12 recorded motions were hand selected from the PEER NGA database.

Seismic isolation systems for buildings are generally selected to achieve higher seismic performa... more Seismic isolation systems for buildings are generally selected to achieve higher seismic performance objectives, such as continued operation or immediate occupancy following a design earthquake event. However, recent large scale tests have suggested that these objectives may be compromised if the shaking includes large vertical acceleration components that are damaging to the nonstructural components and contents. Some research has been conducted to develop three dimensional isolation systems that can isolate the structure from both the horizontal and vertical components of ground motion. In several cases, systems have been proposed without much justification of the target design parameters. Rocking has been noted as a potential concern for structures with 3D isolation systems, and complex systems have been proposed to control the rocking. In this study, the fundamental dynamic response of structures with 3D isolation systems is explored. Target horizontal and vertical spectra for a representative strong motion site were developed based on NEHRP recommendations, and horizontal and vertical ground motions were selected that best fit the target spectra when the same amplitude scale factor was applied to all three motion components. Using a simple model of a rigid block resting on linear isolation bearings, the following aspects are evaluated for a wide range of horizontal and vertical isolation periods: response modes and severity of rocking, horizontal and vertical displacement demands in the isolation bearings, and attenuation of both horizontal and vertical accelerations in the structure relative to the ground acceleration. Preliminary results point to a number of useful observations. For example, rocking appears to be an issue only if the horizontal and vertical isolation periods are closely spaced. Helical spring isolation systems that have been applied to a few structures have this characteristic. However, if the horizontal isolation period is large relative to the vertical isolation period, troublesome rocking can be avoided. In addition, other researchers have proposed systems with vertical isolation periods on the order of 2 seconds, which require large displacement and damping capacity. However, preliminary results suggest that vertical isolation periods as low as 0.5 seconds will be effective in attenuating the vertical acceleration. Limiting the vertical isolation period will make design of a 3D isolation system more feasible with respect to vertical displacement capacity and avoiding rocking.

Mechatronics, 2019

This article was published in Mechatronics