scholarly journals Temperature-Insensitive Structure Design of Micromachined Resonant Accelerometers

Sensors ◽  
2019 ◽  
Vol 19 (7) ◽  
pp. 1544 ◽  
Author(s):  
Yonggang Yin ◽  
Zhengxiang Fang ◽  
Yunfeng Liu ◽  
Fengtian Han
Keyword(s):  
Thermal Stress ◽  
Temperature Sensitivity ◽  
Structure Design ◽  
Experimental Results ◽  
Stress Effect ◽  
Glass Technology ◽  
Temperature Drift ◽  
Die Attach ◽  
Bias Stability

Micromachined resonant accelerometers (MRAs), especially those devices fabricated by silicon on glass technology, suffer from temperature drift error caused by inherent thermal stress. This paper proposes two structure designs to attenuate the effect of thermal stress. The first MRA structure is realized by optimizing the locations of the bonding anchors and utilizing a special-shaped substrate to isolate the thermal stress generated during the die attach process. The second structure is designed using an isolation frame fixed by a single anchor to replace all dispersed anchors associated with the suspension beams and micro-levers. Simulated and experimental results show that both of the MRA structures can effectively reduce the thermal stress effect. The experimental results on one MRA prototype indicate that the differential temperature sensitivity reduces down to 1.9 μg/°C and its 15-day bias stability reaches 1.4 μg.

scholarly journals Die-Attach Structure of Silicon-on-Glass MEMS Devices Considering Asymmetric Packaging Stress and Thermal Stress

Sensors ◽  
2019 ◽  
Vol 19 (18) ◽  
pp. 3979
Author(s):  
Jun Eon An ◽  
Usung Park ◽  
Dong Geon Jung ◽  
Chihyun Park ◽  
Seong Ho Kong
Keyword(s):  
Thermal Stress ◽  
Silicon Wafers ◽  
Experimental Results ◽  
Mems Devices ◽  
Microelectromechanical System ◽  
Die Attach ◽  
Lack Of Control ◽  
Die Bonding ◽  
Glass Process ◽  
Typical Process

Die attach is a typical process that induces thermal stress in the fabrication of microelectromechanical system (MEMS) devices. One solution to this problem is attaching a portion of the die to the package. In such partial die bonding, the lack of control over the spreading of the adhesive can cause non-uniform attachment. In this case, asymmetric packaging stress could be generated and transferred to the die. The performance of MEMS devices, which employ the differential outputs of the sensing elements, is directly affected by the asymmetric packaging stress. In this paper, we proposed a die-attach structure with a pillar to reduce the asymmetric packaging stress and the changes in packaging stress due to changes in the device temperature. To verify the proposed structure, we fabricated four types of differential resonant accelerometers (DRA) with the silicon-on-glass process. We confirmed experimentally that the pillar can control the spreading of the adhesive and that the asymmetric packaging stress is considerably reduced. The simulation and experimental results indicated that the DRAs manufactured using glass-on-silicon wafers as handle substrates instead of conventional glass wafers have a structure that compensates for the thermal stress.

scholarly journals A Silicon Resonant Accelerometer Embedded in An Isolation Frame with Stress Relief Anchor

Micromachines ◽  
2019 ◽  
Vol 10 (9) ◽  
pp. 571 ◽  
Author(s):  
Jian Cui ◽  
Haibing Yang ◽  
Dong Li ◽  
Ziyang Song ◽  
Qiancheng Zhao
Keyword(s):  
Thermal Stress ◽  
Thermal Sensitivity ◽  
High Sensitivity ◽  
Measurement Range ◽  
Dominant Factor ◽  
Stress Effect ◽  
Temperature Drift ◽  
Significant Performance ◽  
The Stability ◽  
Resonant Accelerometer

Bias thermal sensitivity is a significant performance parameter of a silicon resonant accelerometer (SRA) and is normally used to evaluate the degree of engineering practicability. Theoretical analysis demonstrates that temperature-induced stress is the dominant factor that determines the bias temperature drift of the custom-designed SRA. To solve this issue, this paper presents an SRA embedded in an isolation frame with stress insensitive anchor that prevents the resonant beams suffering from the thermal stress along the sense axis and thus improving the bias stability. Moreover, a high sensitivity device is achieved by integrating the vibrating beams with the comb fingers without conventional additional mass design. The experimental results show that the nominal resonant frequency of the SRA is around 93 kHz with the sensitivity and nonlinearity of 223.7 Hz/g and 5.1‰. The thermal sensitivities of the two resonant beams are −27.6 ppm/°C and −28.8 ppm/°C, respectively, which can be considered as the results owing to temperature change of the Young’s modulus without the thermal stress effect. The bias thermal sensitivity and the stability (1σ) after compensation are tested to be approximately 0.7 mg/°C and 1 mg over the temperature range from −40 °C to 60 °C with ±80 g measurement range.

Simulation and experimentation of a magnetorheological brake with adjustable gap

2016 ◽  
Vol 28 (12) ◽  
pp. 1614-1626 ◽  
Author(s):  
Wan-Li Song ◽  
Dong-Heng Li ◽  
Yan Tao ◽  
Na Wang ◽  
Shi-Chao Xiu
Keyword(s):  
Magnetorheological Fluid ◽  
Structure Design ◽  
Experimental Results ◽  
Wear Property ◽  
Braking Performance ◽  
Braking Torque ◽  
The Difference ◽  
The Impact ◽  
Theoretical Analyses ◽  
Magnetostatic Simulation

The aim of this work is to investigate the effect of the small magnetorheological fluid gap on the braking performance of the magnetorheological brake. In this article, theoretical analyses of the output torque are given first, and then the operating principle and design details of the magnetorheological brake whose magnetorheological fluid gap can be altered are presented and discussed. Next, the magnetic circuit of the proposed magnetorheological brake is conducted and further followed by a magnetostatic simulation of the magnetorheological brakes with different sizes of fluid gap. A prototype of the magnetorheological brake is fabricated and a series of tests are carried out to evaluate the braking performance and torque stability, as well as the verification of the simulation results. Experimental results show that the braking torque increases with the increase in the current, and the difference for the impact of the fluid gap on braking performance is huge under different currents. The rules, which the experimental results show, have an important significance on both the improvement of structure design for magnetorheological brake and the investigation of the wear property under different fluid gaps.

FEM Analysis of Contact for Converter Spherical Hinge

2013 ◽  
Vol 365-366 ◽  
pp. 331-334
Author(s):  
Xue Ping Ren ◽  
Jian Da Gao
Keyword(s):  
Numerical Simulation ◽  
Thermal Stress ◽  
Optimum Design ◽  
Theoretical Basis ◽  
Fem Analysis ◽  
Structure Design ◽  
Coupling Field ◽  
Main Components ◽  
Spherical Hinge

The role of converter spherical hinge is one of the main components, combined with practical work and With help of FEM, Thermal Stress coupling field of spherical washer can been obtained through numerical simulation. The result supplies substantial theoretical basis for further structure design and optimum design of mechanism.

scholarly journals Thermal Stress Effect on Density Changes of Hemp Hurds Composites

2016 ◽  
Vol 11 (2) ◽  
pp. 67-76
Author(s):  
Ivana Schwarzova ◽  
Julia Cigasova ◽  
Nadezda Stevulova
Keyword(s):  
Thermal Decomposition ◽  
Thermal Stress ◽  
Composite System ◽  
Gradual Increase ◽  
Bound Water ◽  
Stress Effect ◽  
Original Sample ◽  
Density Reduction ◽  
Filling Agent ◽  
Naoh Solution

Abstract The aim of this article is to study the behavior of prepared biocomposites based on hemp hurds as a filling agent in composite system. In addition to the filler and water, an alternative binder, called MgO-cement was used. For this objective were prepared three types of samples; samples based on untreated hemp hurds as a referential material and samples based on chemically (with NaOH solution) and physically (by ultrasonic procedure) treated hemp hurds. The thermal stress effect on bulk density changes of hemp hurds composites was monitored. Gradual increase in temperature led to composites density reduction of 30-40 %. This process is connected with mass loss of the adsorbed moisture and physically bound water and also with degradation of organic compounds present in hemp hurds aggregates such as pectin, hemicelluloses and cellulose. Therefore the changes in the chemical composition of treated hemp hurds in comparison to original sample and its thermal decomposition were also studied.

Non-Linear Dynamic Magneto Electric Effects in Ferromagnetic-Ferroelectric Layered Composites

2013 ◽  
Author(s):  
Satenik Harutyunyan ◽  
Davresh Hasanyan
Keyword(s):  
Vibration Frequency ◽  
Strain Distribution ◽  
Longitudinal Vibration ◽  
Three Dimensional ◽  
Low Frequency ◽  
Structure Design ◽  
Experimental Results ◽  
Physical Parameters ◽  
Wide Range ◽  
Non Linear

A non-linear theoretical model including bending and longitudinal vibration effects was developed for predicting the magneto electric (ME) effects in a laminate bar composite structure consisting of magnetostrictive and piezoelectric multi-layers. If the magnitude of the applied field increases, the deflection rapidly increases and the difference between experimental results and linear predictions becomes large. However, the nonlinear predictions based on the present model well agree with the experimental results within a wide range of applied electric field. The results of the analysis are believed to be useful for materials selection and actuator structure design of actuator in actuator fabrication. It is shown that the problem for bars of symmetrical structure is not divided into a plane problem and a bending problem. A way of simplifying the solution of the problem is found by an asymptotic method. After solving the problem for a laminated bar, formula that enable one to change from one-dimensional required quantities to three dimensional quantities are obtained. The derived analytical expression for ME coefficients depend on vibration frequency and other geometrical and physical parameters of laminated composites. Parametric studies are presented to evaluate the influences of material properties and geometries on strain distribution and the ME coefficient. Analytical expressions indicate that the vibration frequency strongly influences the strain distribution in the laminates, and that these effects strongly influence the ME coefficients. It is shown that for certain values of vibration frequency (resonance frequency), the ME coefficient becomes infinity; as a particular case, low frequency ME coefficient were derived as well.

Analysis of Hybrid Programming Simulation Based on the Variable Stiffness Ring With Expanding Loop SMA Actuator

2017 ◽  
Author(s):  
Lei Wang ◽  
Zong-quan Deng ◽  
Hao-di Wang ◽  
Hong-hao Yue
Keyword(s):  
Thermal Stress ◽  
Elastic Modulus ◽  
Active Control ◽  
Driving Force ◽  
Structure Design ◽  
Smart Structure ◽  
Space Craft ◽  
Stiffness Variation ◽  
Sma Actuator ◽  
Driving Source

In the development of space craft design index, the requirements of hypersonic space craft control accuracy has been increasingly rigorous. Thin-walled structure is often employed in hypersonic craft to reduce the weight of the load and to save the room. During the flight of the craft, temperature field is produced along the surface and the dynamic properties of the craft structure are obviously changed. The decreasing elastic modulus of the structure material and the appearance of thermal stress lead to the decrease of integral rigidity and stability of the structure, then the thermal flutter appears and control difficulties increase. Shape Memory Alloy (SMA) has the advantages of the considerable driving force in the compact volume and the simple driving method. By the combination of actuator structure design and stiffness control, the smart structure is able to make active control to the thermal stiffness variation. In this paper, the apex high-temperature area is equivalent to a ring structure. Finite difference method is employed firstly to transform the governing partial differential equation into discrete finite difference equations. Then the elastic modulus change, thermal stress and tension along the circumference are considered comprehensively to propose the calculation formulas of equivalent young’s modulus. The discrete dynamic matrix model is obtained containing the control terms of SMA. To solve the big-matrix calculation and multiple iterated large data problem, hybrid program is developed with C++ and MATLAB. Finite element software is employed to make optimization analysis to design an expanding loop actuator containing SMA as driving source, variable thickness loops of spring steel as expanding units, and universal-ball pre-loading units. On the basis of that, the thermal stiffness variation active control system with smart structure is developed based on expanding loop SMA actuator. After the analysis of examples, the variation law of the needed SMA driving force is obtained. The distribution position and quantity of the driving source is optimized. This research provides reference for the Theoretical Analysis and Simulation of structure stiffness active control and adaptive control of the aircraft employing smart material. The research results have guiding significance for the smart structure design of hypersonic aircraft in the future.

Ink-jetting for Electronic Assembly

2010 ◽  
Vol 2010 (1) ◽  
pp. 000929-000934
Author(s):  
Georg Meyer-Berg ◽  
Gottfried Beer ◽  
Klaus Pressel
Keyword(s):  
Void Formation ◽  
Experimental Results ◽  
Special Focus ◽  
Electronic Assembly ◽  
Filler Size ◽  
Die Attach ◽  
Ink Jet ◽  
The Future

We report experimental results on applying ink-jetting to dedicated system-in-package technologies. Special focus is on die-attach, vertical and horizontal interconnects. Our experiments on die attach experiments demonstrate that today we have still too high expenses to adapt materials, filler size and viscosity. The filling experiments of 150μm diameter vertical through encapsulant vias for package-on-package applications with ink-jetting showed void formation, which requires still smaller ink jet drops in the future. For formation of horizontal interconnects, e.g. for rerouting, by ink-jetting we observe that a functionalization of the surfaces e.g. with plasma or sulfur acid is required. Based on these project results and experience we suggest a roadmap for ink-jetting using parallel nozzles and single nozzles.

scholarly journals Analysis and Compensation of Bias Drift for a Micromachined Spinning-Rotor Gyroscope with Electrostatic Suspension

Sensors ◽  
2020 ◽  
Vol 20 (6) ◽  
pp. 1799
Author(s):  
Shunyue Wang ◽  
Fengtian Han
Keyword(s):  
Compensation Scheme ◽  
Short Term ◽  
Temperature Drift ◽  
Position Sensing ◽  
Bias Drift ◽  
Bias Stability ◽  
Time Drift ◽  
Rotor Structure ◽  
Bias Compensation

Bias stability is one of primary characteristics of precise gyroscopes for inertial navigation. Analysis of various sources of the bias drift in a micromachined electrostatically suspended gyroscope (MESG) indicates that the bias stability is dominated by the temperature-induced drift. The analytical results of temperature drift resulting from the rotor structure and capacitive position sensing electronics are modeled and analyzed to characterize the drift mechanism of the MESG. The experimental results indicate that the bias drift is mainly composed of two components, i.e., rapidly changing temperature drift and slowly changing time drift. Both the short-term and long-term bias drift of the MESG are tested and discussed to achieve online bias compensation. Finally, a neural network based-bias compensation scheme is presented and verified experimentally with improved bias stability of the MESG.

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