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The subject of this paper is the buckling behavior of thin bar stiffeners attached to plates which are subjected to normal pressure loadings. The stiffeners are mathematically modeled by a nonlinear beam theory recently derived. An analytical solution is obtained to the beam buckling equations. The curvature of the centerline along the beam's base at the buckling load is expressed in terms of the beam's thickness, height, and rotational stiffness. Analytical results are compared with an experiment recently performed.
DESIGN EQUATIONS FOR TRIPPING OF STIFFENERS UNDER INPLANE AND LATERAL LOADS
Abstract : A series of design oriented equations to predict the tripping (lateral-torsional instability) of stiffeners under inplane and lateral loads has been developed which will allow this mode of failure to be more comprehensively addressed in the early stages of structural design. This type of failure is characterized by a twisting of the stiffener about its line of attachment to the plating and has been demonstrated by some recent British grillage tests to have serious potential as a primary mode of failure. The solutions developed take into account the effects of the rotational resistance provided by the plating to which the stiffener is attached, non-linear material and structural behavior by means of a tangent modulus type approach, and stiffener web deformations (for inplane loading). The equations are suitable for manual calculations but particularly powerful applications are possible when they are teamed up with a desk-top type mini-computer.
Fully Integrated Bidirectional CMOS-MEMS Flow Sensor With Low Power Pulse Operation
Leveraging More-than-Moore technology, we demonstrate an integrated CMOS MEMS flow sensor via a very compact system on chip (SoC) that can sense the bidirectional N2 gas flow. Our SoC features a very low-noise instrumentation amplifier that is implemented on a CMOS wafer and serves as a readout integrated circuit for a thermoresistive micro-calorimetric flow sensor which is fabricated on a MEMS wafer. A compact heterogeneous integration is achieved by combining the two wafers via the proprietary InvenSense AlN process. The measured sensitivity of our CMOS MEMS flow sensor is 98 mV/sccm which is three times better than the state-of-the-art counterpart. The flow range measured by our SoC is from −26 to 26 m/s (from −50 to 50 sccm). Moreover, the pulsed heater operation makes this proposed SoC flow sensor a very low power (<9 mW) and, thus, a promising candidate for the Internet-of-Things applications in smart home/green buildings.