SPring-8

For each of these applications, Liteflex springs promised the potential for improved durability, ride, isolation and packaging. Nevertheless, lack of proper distribution channels and the higher cost of the manufacturing process kept the technology fi-om expanding. During 

2000 Delphi s strategic business plan took it in a direction that no longer included its RP springs product line so the company decided to have the intellectual property evaluated. Because Delphi s springs were manufactured with RP material, NCC was selected to participate in the evaluation process. This step led to NCC identifying an opportunity to retain important technology for Dayton. 

Arvin Meritor has also fostered a companion project as well. The trio will work to develop suspension components designed with NCC s patented process Litecast . 

A zigzag configuration may be seen as a number of separate beams each with one end fixed. The top beam is loaded (F) either along its entire length or at a fixed point. This load gives rise to deflection y at its free end and moment M at the fixed end. The second beam is then loaded by moment M (upward) and load F (the effective portion of load F, as determined by the various angles) at its fi ee end. This moment results in deflection y2 at the free end and moment M2 at the fixed end (that is, the free end of the next beam). The third beam is then loaded by M2 (downward) and force F2 (the effective portion of Fi), and so on. 

Microelectromechanical systems (MEMS) respond to forces that act on them. The forces can either be external to the MEMS device, such as the measurement of acceleration forces in an accelerometer, or from internal forces, such as an electrostatic force in an actuator. In many cases the resulting deformations can be calculated using one-dimensional linear spring analysis based on Hooke s Law  

Here E, the constant of proportionality between the stress a (stimulus) and strain e (response), is called the modulus of elasticity, or Young s modulus. is a property of the material that indicates how stiff it is. Young s modulus for polysilicon is approximately 160 GPa. Young s modulus for single crystal silicon depends on the crystallography. E is 

169 GPa parallel to the wafer flat for a (100) oriented wafer and 130 GPa at 45 degrees to the wafer flat. The relation between stress and strain can be put into the same form as Hooke s Law, relating the lengthening (shortening) of the beam to the tensile (compressive) force acting on it  

A beam of length L that is clamped at one end and subjected to a bending force F acting on the free end will deflect according to 

Here I is the moment of inertia of the beam, where the beam has a width w t and the force F is pushing along the normal to the thin direction. For our example polysilicon beam, we would get a deflection 

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Tests on vehicles have shown that the volatility index as defined expresses satisfactorily the fuel contribution during hot operation of the engine (Le Breton, 1984). In France, specifications stipulate that its value be limited to 900, 1000 and 1150, respectively, according to the season (summer, spring/fall, winter). The automobile manufacturers, being even more demanding, require in their own specifications that the FVI not be exceeded by 850 in summer. 

As of 1993, France has selected classes 1, 3 and 6, corresponding to the season summer, fall/spring, winter. 

Nesvijski, E.G., Nogin, S.I. Acoustic Emission Technics for Nondestructive Evaluation of Stress of Concrete and Reinforced Concrete Structures and Materials. Third Conference on Nondestructive Evaluation of Civil Structures and Materials, Boulder, CO, 1996. Nesvijski, E. G. Failure Forecast and the Acoustic Emission Silence Effect in Concrete. ASNT s Spring Conference, Houston, TX, 1997. 

Eddy Currents ttike their name from the swirls (eddies) observed in turbulent water flow. The Greek mythology tells us about Charybdis. A monster eddy current between Italy and Sicily whose attractive field pulled unwary sailors to their destruction. Our kind of eddy currents are usually not so dangerous, they flow in electrical conductors and are a branch of Electromagnetics. Where does that spring from Could it make eddy currents the very oldest NDT technique ... 

This projeet has presented considerable challenges and is due to be completed in Spring 1998. 

J.J. Munro III, R. Grimm, T. Kaflal ASNT Spring Conference, Norfolk VA (1996)... 

Minkov,D. and Shoji,T., To be presented at the 1998 Annual Spring Meeting of JSME in Tokyo... 

The system is to be qualified under the new regulations for ISI in Swedish nuclear plants, SKIPS, during the spring of 98 and the pre-trials for these qualifications has produced very promising results. 

A major advance in force measurement was the development by Tabor, Win-terton and Israelachvili of a surface force apparatus (SFA) involving crossed cylinders coated with molecularly smooth cleaved mica sheets [11, 28]. A current version of an apparatus is shown in Fig. VI-4 from Ref. 29. The separation between surfaces is measured interferometrically to a precision of 0.1 nm the surfaces are driven together with piezoelectric transducers. The combination of a stiff double-cantilever spring with one of a number of measuring leaf springs provides force resolution down to 10 dyn (10 N). Since its development, several groups have used the SFA to measure the retarded and unretarded dispersion forces, electrostatic repulsions in a variety of electrolytes, structural and solvation forces (see below), and numerous studies of polymeric and biological systems. 

Fig. VI-4. Illustration of the surface force apparatus with the crossed-cylinder geometry shown as an inset. The surface separations are determined from the interference fringes from white light travelling vertically through the apparatus. At each separation, the force is determined from the deflection in the force measuring spring. For solution studies, the entire chamber is filled with liquid. (From Ref. 29.)...

Dynamic models for ionic lattices recognize explicitly the force constants between ions and their polarization. In shell models, the ions are represented as a shell and a core, coupled by a spring (see Refs. 57-59), and parameters are evaluated by matching bulk elastic and dielectric properties. Application of these models to the surface region has allowed calculation of surface vibrational modes [60] and LEED patterns [61-63] (see Section VIII-2). 

Use Equation VIII-1 to determine the effective mass of the cantilever if the cantilever has a spring constant C = 20 N/m, the minimum detectable force gradient is hF/dz = 4 X 10 N/m, and the frequency shift is 200 kHz. How does the frequency shift depend on distance from the surface if the force has a 1/z distance dependence ... 

A second general type of procedure, due to McBain [29], is to determine n by a direct weighing of the amount of adsorption. McBain used a delicte quartz spiral spring, but modem equipment generally makes use of a microbalance or a transducer. An illustrative schematic is shown in Fig. XVII-6. 

Classically, the nuclei vibrate in die potential V(R), much like two steel balls coimected by a spring which is stretched or compressed and then allowed to vibrate freely. This vibration along the nuclear coordinated is our first example of internal molecular motion. Most of the rest of this section is concerned with different aspects of molecular vibrations in increasingly complicated sittiations. 

Wlien a spring is stretched or compressed, work is done. If the spring is the system, then the work done on it is simply... 

Figure Bl.19.16. Schematic view of the force sensor for an AFM. The essential features are a tip, shown as a rounded cone, a spring, and some device to measure the deflection of the spring. (Taken from [74], figure 6.)...

As the tip is brought towards the surface, there are several forces acting on it. Firstly, there is the spring force due to die cantilever, F, which is given by = -Icz. Secondly, there are the sample forces, which, in the case of AFM, may comprise any number of interactions including (generally attractive) van der Waals forces, chemical bonding interactions, meniscus forces or Bom ( hard-sphere ) repulsion forces. The total force... 

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