The sensing element essentially is a proof mass (also known as seismic mass). The proof mass is attached to a spring of stiffness k which in turn connected to its casing. Further, a dash pot is also included in a system to provide desirable damping effect; otherwise system might oscillate at its natural frequency. When the system is subjected to linear acceleration, a force equaling to mass times the acceleration acts on the proof-mass. This causes the mass to deflect; the deflection is sensed by a suitable means and is converted into an equivalent electrical signal.
When the tip approaches toward the sample it experience the amount of force which is dependent on the spring constant (stiffness) of the cantilever and the distance between the tip and the sample. This force is expressed in term of hooks law F=-k.x F= Force K= spring constant X= cantilever deflection If the spring constant of cantilever is less than surface stiffness the cantilever bends and then we can measure the deflection from cantilever. This typically results in forces ranging from nN (10 ) to μN (10-6) in the open air. What are tips and cantilever made of? The probes that we are using (i.e tip and cantilever) are generally made from Si or Si3N4.The Tip is generally pyramidal and tetrahedral in shape Depending on the length, materials and shapes we can moderate the spring constants and the resonant frequency (the frequency at which the resonance condition is achieved).
Nonlinear static procedures are now widely used in engineering practice to predict seismic demands in building structures. The simplified versions of NSP based on lateral load capacity such as those recommended in ATC-40 and FEMA-356 have well-documented limitations in terms of their inability to account for higher mode effects and modal variation resulting from inelastic behaviour. Results from the analytical study indicate that peak response measures such as inter-story drift and component plastic rotations more consistently than the other NSP’s investigated in the
The phenomenon is also known as the Magnetorheological effect. The yield stress of the fluid when in its active ("on") state can be controlled very accurately by varying the magnetic field intensity. Upshot of this is the fluid's ability to transmit force can be controlled with an electromagnet which gives rise to many possible control based applications. MRFs also possess outstanding rheological characteristics, for example high yield stress and shear viscosity, that can be altered by tuning an external magnetic field.
Methodology: Blocking floor method has been employed to reduce the vibration impact in the buildings due to the passage of the trains. The basic theory and principle for the working of this method is based on the fact that the vibrations are transferred to the upper side between the consecutive stories through the structure of columns and beams in the building. So this method basically mitigates the vibrations induced in the building structures by continuously decreasing their amplitude and impact. The reduction in the vibration is achieved through the impedance or physical resistance or obstacles provided by the floor slabs and girders. This model is structured on the fact that in a model structure of a building, vibrations were produced artificially and the speed and velocity of these vibrations were measured for each floor at its center.
BUCKLING It is defined as; “Buckling i characterized by a sudden sideways failure of a structural member subjected to high compressive stress, where the compressive stress at the point of failure is less than the ultimate compressive stress that the material is capable of withstanding”. [Wikipedia] In tubing the presence of internal and external pressures cause complications. Assume a small section of vertical tubing, a bend is present with internal pressures acting on both sides of the tubing. Thus buckling is being promoted by compression and internal pressures (pi) whereas external pressures (po) and tension is minimizing the effect of buckling. This is categorized in the term of effective tension (Feff).
Chapter 4 SOFTWARE FAMILIARIZATION AND VALIDATION STUDY FE analysis is considered to be a valuable analytical tool in structural engineering domain. Several commercial FE based software are available for analysis and design of structural systems. If the analysis makes assumptions or requires additional data input along these lines, care should be taken to understand and work within the limitations of the analysis. Structural analysis programs should be fully understood with respect to the theory and approximations used in them. Notations and sign conventions with respect to the loading, properties and boundary conditions must be clearly understood.
Todays, the plates are widely used in various industries such as shipbuilding, aircraft, aerospace, car manufacturing industries, and etc. The plates are under different forces therefor studying on them under different loading and boundary conditions is important. It is possible (maybe) the plate subjected to compressive forces in an engineering structure that it will result buckling. Because of different boundary conditions of plates has been used in the wings of aircraft or in the hulk, the plates are under linearly distributed and uniform compressive in-plane forces, therefore it is important to study the phenomenon of plate buckling. There are many studies about buckling of plates, Abolghasemi and et al.
In an earthquake (seismic waves), a frame with suitable properties and data can develop plastic hinges that will absorb energy and allow the frame to withstand actual displacements that are larger than calculated in an elastic-based design concepts. In modern moment frames, the ends of beams and columns, being the locations of max seismic moment, are designed to sustain inelastic behavior associated with plastic hinging over many cycles and load reversals. Frames that are designed and detailed for the ductile behavior are called “special” moment frames. Frames without special seismic detailing depend on the reserve strength inherent in the design of the members. The basis of this reserve strength is the load factors in the safety under working-stress design methods.
This is found that almost all of the mechanised energy is converted into heat during chip creation process that will improve the temperature to high ideals in the cutting sector. The heat made are likely to cause almost all of the technical and economical problems while engineering. During machining heat is made in the reducing zone from three distinctive zones: Primary shear deformation zone (PSDZ), secondary shear deformation zone (SSDZ) and tertiary shear deformation sector (TSDZ). Major part of heat is made due to severe plastic deformation in an exceedingly narrow zone called PSDZ. Further heating is made in the SSDZ anticipated to friction between tool and chip as well as shearing at the chip-tool interface.