Magnetostrictive Self-Diagnosing Smart Bolts

The paper presents the concept of self-diagnosing smart bolts and its experimental validation. In the present research such bolts are designed, built, and experimentally tested. As a key element of the design, wires of Galfenol (alloy of iron and gallium) are used. This material shows magnetostrictive properties, and, at the same time, is sufficiently ductile to follow typical deformation of rock bolts, and is economically affordable. Two types of Galfenol were used: Ga10Fe90 and Ga17Fe83. The wires have been installed in bolts using two designs — in a drilled central hole or in a cut along the side — and the bolts were tested for generation of the magnetic field under three-point bending loading. To measure the magnetic field in the process of deformation, a magnetometer that utilizes the GMR effect was designed, built, and compared with one utilizing the Hall effect. It is shown that (1) magnetic field generated by deformation of the smart bolts at the stress level of plastic deformation is sufficient to be noticed by the proposed magnetometer; however, the magnetometer using Hall effect is insufficient; (2) Ga10Fe90 produces higher magnetic fields than Ga17Fe83; (3) the magnetic field in plastically bended bolts is relatively stable with time.

Making Ethics Education Personal

Accredited engineering programs are required to provide instruction in ethics. A primary goal of ethics education is to develop and improve a student’s ability to recognize situations involving ethical decisions and to encourage development of a personal framework by which to decide what to do. A major challenge in ethics education is to personalize situations that are typical of those that the students will likely encounter. This paper presents techniques that enable a faculty member to act as a facilitator in the discussion of ethics rather than as an instructor.

Microstructure Evolution and Bond Formation at the Contact Interface During Ultrasonic Consolidation Process

In this paper a cellular automata-finite elements (CAFE) model is developed by combining traditional finite elements (FE) model and cellular automata (CA) model. The microstructure under different process conditions of ultrasonic consolidation (UC) process for Al 7075 is studied. It is found that higher energy input process conditions (higher applied load and sonotrode oscillation amplitude, lower sonotrode travel speed) will lead to a higher value of dynamic recrystallization (DRX) fraction for UC deposited foils. The mean dislocation density of the UC deposited material will increase with the applied load while it decreases with the increase of sonotrode travel speed and oscillation amplitude.

Characterization of Mechanical and Viscoelastic Properties of SC-15 Epoxy Nanocomposites Reinforced With Multi-Walled Carbon Nanotubes, Nanoclay and Binary Nanoparticles

Mechanical and viscoelastic properties of polymer nanocomposites reinforced with carboxyl functionalized multiwalled carbon nanotubes (COOH-MWCNT), montmorillonite nanoclays (MMT) and MWCNT/MMT binary nanoparticle were investigated. In this study, 0.3 wt. % of COOH-MWCNT, 2 wt. % of MMT and 0.1 wt. % COOH-MWCNT/2 wt. % MMT binary nanoparticles by weight of epoxy were incorporated to modify SC-15 epoxy resin system. The nanocomposites were subjected to flexure test, dynamic mechanical and thermomechanical analyses. Morphological study was conducted with scanning electron microscope. Addition of each of the nanoparticles in epoxy showed significant improvement in mechanical and viscoelastic properties compared to those of control ones. But, best results were obtained for addition of 0.1% MWCNT/2% MMT binary nanoparticles in epoxy. Nanocomposites modified with binary nanoparticles exhibited about 20% increase in storage modulus as well as 25° C increase in glass transition temperature. Flexural modulus for binary nanoparticle modified composites depicted about 30% improvement compared to control ones. Thus, improvement of mechanical and viscoelastic properties was achieved by incorporating binary nanoparticles to epoxy nanocomposites. The increase in properties was attributed to synergistic effect of MWCNTs and nanoclay in chemically interacting with each other and epoxy resin as well as in arresting and delaying the crack growth once initiated.

A Decision Model for Selecting the Optimum Oil Production Profile Using Multi Criteria Decision Making and Social Choice Theory

Applying a MCDM model has many benefits for decision makers in the course of oil field master development plans preparation and evaluation. In this study, a multi-criteria decision making model is proposed in order to achieve an optimum production profile. The most important criteria and parameters for selection of best production profile are identified. These parameters are derived by several interviews with Iranian oil Industry’s experts. The candidate alternatives for production profile are ranked using a combination of group decision making approach and social choice theory. The degree of group consensus is evaluated by using a statistic model to confirm the validity of decision making model.

A Cellular Automaton Model and its Application on Emotional Infections

Emotional contagion has been a focus problem in the current fields of psychology and organizational behavior. Based on the theoretical analysis of the emotional contagion mechanisms and probabilistic theory, a cellular automaton (CA) model has been proposed to simulate the process of emotional contagion. And with the help of this CA model, we study the gross features of employees’ positive emotions in the evolution of emotional contagion and explore the effects of employees’ ability to transport emotion susceptibility and intimacy on the reaction process. The results indicate that employees’ ability to transport positive emotion susceptibility and intimacy are positive related to the emotional contagion between employees.

Comparison of Hardness and Microstructures Produced Using GMAW and Hot-Wire TIG Mechanized Welding of High Strength Steels

For high productivity weld fabrication, gas metal arc welding (GMAW) is typically used since it offers a combination of high deposition rate and travel speed. Recent advances in power supply technologies have increased the deposition rates in hot-wire tungsten inert gas (HW-TIG) welding, such that it is possible to achieve parameters which may be comparable to those used in GMAW for pressure vessels and some pipeline applications. However, these two processes have drastically different deposition efficiencies and heat input characteristics. The purpose of the present study is to examine GMAW and HW-TIG bead-on-plate deposits in terms of mechanical properties, deposition rate, and heat affected zone (HAZ) thermal cycles when identical travel speed and wire feed speeds are applied with a ER90S-G filler metal. The results demonstrate that HW-TIG can be applied with comparable travel and wire feed speeds to GMAW, while providing a more uniform weld bead appearance. Based on weld metal microhardness values, it is suggested the effective heat input is lower in HW-TIG compared to GMAW, since the average hardness of the weld metal is slightly higher.

On a Generalized Approach for Design of Compliant Mechanisms Using the Pseudo-Rigid-Body Model Concept

This paper provides a generalized approach for the design of compliant mechanisms. The paper discusses the implicit uncoupling, between the kinematic and energy/torque equations, enabled by the pseudo-rigid-body model concept, and utilizes it for designing a variety of compliant mechanism types for a wide-range of user specifications. Pseudo-rigid-body four-bar mechanisms, with one to four torsional springs located at the revolute joints, are considered to demonstrate the design methodology. Mechanisms are designed for conventional tasks, such as function, path and motion generation, and path generation with prescribed timing, with energy/torque specified at the precision-positions. State-of-the-art rigid-body synthesis techniques are applied to the pseudo-rigid-body model to satisfy the kinematic requirements. Energy/torque equations are then used to account for the necessary compliance according to the user specifications. The approach utilizes a conventional, simple yet efficient optimization formulation to solve energy/torque equations that allow a designer to i) achieve realistic solutions, ii) specify appropriate energy/torque values, and iii) reduce the sensitivities associated with the ‘synthesis with compliance’ approach. A variety of examples are presented to demonstrate the applicability and effectiveness of the approach. All of the examples are verified with the finite element software ANSYS®.

Characterization of Nitinol as a Servo-Biomimetic for Facial Muscles

This paper presents the electrodynamic characterization of Nitinol wire and investigates its potential as a servo-actuator that can be utilized to recreate complex low-power muscle movements, such as those in facial muscle groups. Nitinol (NiTi) is a type of shape memory alloy (SMA) which recovers its original length after experiencing large deformation when heated above an austenite finish temperature. This shape memory effect is associated with the phase transformation between the martensite phase and austenite phase. By varying a current through the Nitinol wire, its temperature can be accurately controlled and by extension so can its internal strain or stress. The purpose of this work is twofold: 1) to examine the causal relationships between current, temperature, strain and stress in the Nitinol wire, and 2) to demonstrate the feasibility of a simple closed-loop control system such that this type of wire can be used as a servo-actuator in both position control and force control applications. Experimental results show a basic level of servo-control, achieving successful position and force tracking of a command signal. These results demonstrate the feasibility of creating networks of Nitinol wires which can mimic complex motion patterns of certain facial muscle groups.

Interlaminar Tensile Strength of CFRP Composites Reinforced With Interleaved Carbon Nanotube Sheets

Unidirectional carbon-fiber-reinforced polymer (CFRP) composites with interleaved carbon nanotube (CNT) sheets were manufactured using a heated press. The effect of CNT sheets on the interlaminar tensile strength (ILTS) of composite laminates was measured using curved beam bending tests. Two sets of [0]24 T800S/3900-2B specimen were prepared using carbon fiber prepregs and non-woven CNT sheets, with specimen thickness and radial geometries conforming to ASTM D6415. Epoxy resin loaded CNT sheets were inserted in the mid-radius region of curved beam specimens during the lay-up process. The measured interlaminar tensile strengths (ILTS) were compared between the CNT-enhanced and baseline CFRP specimens. Specimen fracture surfaces were examined with optical microscopy to determine the mode of failure and to confirm that fracture occurred at the location with the highest radial stresses. CNT sheet enhancements have shown to improve ILTS by 42%, with all failures initiating at the CNT interlayer and the polymer matrix interface.