Sine Vibration Testing Research Articles

Optimization and verification of mechanical design for small total reflection optics

Mechanical performance assurance is one of the key concerns in the design of small total reflection optics. This article addresses the issue of insufficient strength margin in the design of a total reflection optics for a space photoelectric sensor. Firstly, structural design optimization research was conducted on the optics, and the effectiveness of structural improvement was verified through finite element analysis; Secondly, a concave analysis was conducted under mechanical test conditions to further reduce the risk; Afterwards, the accuracy of the simulation results was verified by comparing the simulation with the experiment through small-scale random vibration tests; Finally, sine vibration tests, random vibration tests, shock tests, acceleration tests were conducted on the entire machine, and optical tests were conducted before and after the tests. The experimental and testing results indicate that the entire machine has passed the mechanical test assessment at the appraisal level and maintained good optical performance. The total reflection optics optimized by mechanical design meets the requirements of engineering applications.

Lightweight Design for Active Small SAR S-STEP Satellite Using Multilayered High-Damping Carbon Fiber-Reinforced Plastic Patch

In the launch environment, satellites are subjected to severe dynamic loads. These dynamic loads in the launch environment can lead to the malfunction of the payload, or to mission failure. In order to improve the structural stability of satellites and enable the reliable execution of space missions, it is necessary to have a reinforcement structure that reduces structural vibrations. However, for active small SAR satellites, the mass requirements are very strict, and this makes it difficult to apply an additional structure for vibration reduction. Therefore, we have developed a carbon fiber-reinforced plastic (CFRP)-based laminated patch to obtain a vibration reduction structure with a lightweight design for improving the structural stability of an S-STEP satellite. To verify the vibration reduction performance of the CFRP-based patch, sine and random vibration tests were conducted at the specimen level. Finally, the structural stability of the S-STEP satellite with the proposed CFRP-based laminated patch was experimentally verified using sine and random vibration tests. The validation results indicate that the CFRP-based laminated patch is an efficient solution which can effectively reduce the vibration response without the need for major changes to the design of the satellite structure. The lightweight vibration reduction mechanism developed in this study is one of the best solutions for protecting vibration-sensitive components.

Euclid Spacecraft Sine Vibration Test Prediction Through the Virtual Shaker Testing Technique

In the space industry, the sine vibration test prediction of a spacecraft is approached numerically by exploiting the spacecraft finite element model (FEM). A frequency response analysis is run for this purpose, and the spacecraft is assumed in hard-mounted boundary conditions, thus neglecting the shaker compliance. Consequently, unrepresentative structural predictions may lead to test article under- or overtesting, as well as incorrect FEM mathematical model updating, and affect the proper fulfilment of the launcher frequency requirements. Virtual shaker testing (VST) solves these issues by including the shaker FEM within the computational framework and exploiting a coupled transient analysis inclusive of the vibration control system. In this study, VST is applied as a pioneering predictive tool to study spacecraft–shaker dynamic coupling of the Euclid spacecraft, before mechanical qualification tests. Experimental measurements such as test control accelerations, lateral bending moments, cross talk, and notching were effectively predicted and compared to the classical approach. Compression factor effects were investigated through a sensitivity analysis, and test predictions were strongly influenced by this parameter. VST has been shown to be a valid methodology to faithfully simulate the sinusoidal test and extract data otherwise unavailable.

High Damping Passive Launch Vibration Isolation System Using Superelastic SMA with Multilayered Viscous Lamina

Whole-spacecraft launch-vibration isolation systems are attractive for achieving the goal of better, faster, cheaper, and lighter small satellites by reducing the design-load and vibration-test specifications for on-board components. In this study, a three-axis passive launch-vibration isolation system, based on superelastic shape memory alloy (SMA) technology, was developed to significantly attenuate the dynamic launch loads transmitted to a small satellite. This provides a superior damping characteristic, achieved by superelastic SMA blades stiffened by multilayered thin plates with viscous lamina adhesive layers of acrylic tape. The basic characteristics of the proposed isolation system with various numbers of viscoelastic multilayers were obtained through a static load test. In addition, the effectiveness of the design was validated through a launch environment simulating sine and random vibration tests.

CubeSat’s Deployable Solar Panel with Viscoelastic Multilayered Stiffener for Launch Vibration Attenuation

Ensuring the structural safety of a deployable solar panel under a severe launch vibration environment is one of the important factors for a successful CubeSat mission. A CubeSat’s deployable solar panel proposed in this study is effective to guarantee the structural safety of solar cells by attenuating launch loads owing to the superior damping characteristic achieved by a multilayered stiffener with viscoelastic acrylic tapes. The demonstration model of 3 U CubeSat’s deployable solar panel was fabricated and tested to validate the effectiveness of the proposed design. The basic dynamic characteristics of the solar panel were measured through free-vibration tests according to the various layers of the stiffener. Moreover, the characteristics of the deployed solar panel were measured and investigated under various temperatures to predict its capability under in-orbit operation. The effectiveness of the proposed design for launch vibration attenuation was demonstrated through qualification level sine and random vibration tests.

Development of shock-absorbing insert for honeycomb sandwich panel

Pyrotechnic separation devices have been widely used in various missions of spacecraft in order to separate the structural parts with high reliability. Although they afford advantages of cost-effectiveness and high reliability, pyrotechnic separation devices generate an intensive dynamic response called pyroshock, which can lead to fatal damage to the mounted electronic equipment. Previous studies have attempted to resolve these issues with a shock isolator. However, these studies have limitations such a possible dynamic instability in low frequency and complexity in design. In the present study, a novel design of the sandwich insert is proposed to achieve enhanced shock attenuation without a shock isolator. Static-load tests were conducted to validate the structural performance of the shock-absorbing insert. In order to observe the attenuation performance, shock propagation and response experiments were carried out with consideration that the inserts were utilized to connect parts and to mount devices on the panel. In addition, swept sine vibration tests were carried out to investigate the dynamic response in low frequency. The shock-absorbing insert reduced propagating shock for the joint structure, and the shock response of the mounted equipment was significantly attenuated. The novel shock-absorbing insert saves space and is dynamically stable, and furthermore has the ability to protect the small electronic equipment, which is mounted on the honeycomb sandwich panel, from severe shock. These advantages make it a suitable insert for space structure application for connecting parts or mounting equipment.

Study on multi-axis sine vibration test control techniques

This paper describes several key aspects about multi-axis sine vibration test control techniques including the identification of the system frequency response function, synchronization of the input and output signals, the generation of the sinewave, the control algorithm, etc. A multi-axis sine vibration controller is developed based on these key techniques and the major framework of the controller is introduced. Finally, a dual axial experiment is carried out by the controller. The test results show the feasibility of the control algorithm and the good control strategy of the multi-axis sine vibration controller in which the key techniques are realized.

Viscoelastic multilayered blade-type passive vibration isolation system for a spaceborne cryogenic cooler

This paper proposes a blade-type passive vibration isolator, realized by multilayered thin metal plates with viscoelastic acrylic tapes, to attenuate the micro-jitter induced by a spaceborne cryogenic cooler. Structural safety of the cooler under severe launch loads is assured without implementing a launch-lock device. One advantage of the isolator is that the implementation of a 1G compensation device is unnecessary during on-ground micro-jitter measurement tests. Moreover, a stable jitter reduction performance could be obtained owing to the unsusceptible alignment sensitivity of the isolator. Free-vibration tests were performed for various temperature conditions to acquire the basic characteristics of the isolator. The effectiveness of the isolator design in launch environments was demonstrated through qualification-level sine vibration and random vibration tests. The micro-jitter isolation capability regarding the isolator alignment shift was confirmed through on-ground micro-jitter estimation test. Besides, the characteristic variations of the viscoelastic multilayered blade isolator in on-orbit thermal vacuum environments were investigated.

Development of 6 U CubeSat’s Deployable Solar Panel with Burn Wire Triggering Holding and Release Mechanism

In the present work, a deployable solar panel based on a burn wire triggering holding and release mechanism was developed for use of 6 U CubeSat. The holding and release mechanism was designed based on a nichrome burn wire cutting method widely used for CubeSat applications. However, it provides a high loading capability, reliable wire cutting, multiplane constraints, and handling simplicity during the tightening process of wire. A demonstration model of a printed circuit board-based solar panel stiffened by a high-pressure fiberglass-laminated G10 material was fabricated and tested to validate the effectiveness of the design and functionality of the mechanism under various test conditions. The structural safety of the solar panel combined with the mechanism in a launch vibration environment was verified through sine and random vibration tests at qualification level.

Dynamic Simulation and Vibration Test of the Active Potential Controller

The Active Potential Controller was used to avoid the risk of damaging the life of astronauts outside spaceships in outer space by controlling the potential of the spaceship. This paper analyzed the structure of the Active Potential Controller by dynamic simulation, including setting up a finite element method (FEM) model, modal character and frequency response. At last, the designing and analysis was proved by the data from a vibration test. In this field, decreasing the weight was a key theme, the goal is cutting the cost. But cancelling or improving the sine vibration test could also save a lot cost, either for the payload or the satellite.

Vibration Testing of Absolute Pressure Sensor for a Flush Air Data System (FADS)

ABSTRACT Flush Air Data Sensing System (FADS) is an important subsystem required for a winged re-entry vehicle. It essentially makes use of surface pressure measurements located at a suitable position in the vehicle for deriving the air data parameters of the vehicle such as angle of attack, angle of sideslip, Mach number, etc. These air data parameters are used by the control and guidance system for carrying out gain scheduling, trim scheduling of control surfaces and overall flight management. The accuracy of the pressure sensors used in FADS is critical in achieving the targeted accuracy of the air data parameters. In the FADS system considered in this paper, piezoresistive MEMS-based pressure sensors are used. The FADS system is located in the nosecone of the vehicle which is a region prone to vibration during transportation as well as during flight. It is essential that the pressure sensors perform with the desired accuracies in spite of the vibration environment. Sine and random vibration testing are carried out as part of qualification testing of the vibration sensors of FADS. Analysis of the test results shows that the accuracies demanded by the system are provided by the pressure sensors under the vibration environment.

Q-band cross-coupled dielectric resonator filter using TM mode for satellite application

AbstractA new structure of Q-band filter comprising rectangular high-permittivity dielectric resonators (DR) operating at TM11δ mode is introduced. The resonator shows high-quality factor (Q) and wide spurious free window compared with other technologies available at Q-band for realizing filters. Low permittivity ceramic material (quartz) is used as a support for holding DR at the center of the cavity. An eight-pole cross-coupled band-pass filter having a bandwidth of 225 MHz at 38.5 GHz was realized. Resonant coupling structure is introduced to realize cross-coupling in filter. The resonator assemblies were optimized precisely to achieve effective linear frequency drift over temperature of the order of 2 ppm/°C. The filter also survived severe sine and random vibration test for satellite application.

A new compound control method for sine-on-random mixed vibration test

Vibration environmental test (VET) is one of the important and effective methods to provide supports for the strength design, reliability and durability test of mechanical products. A new separation control strategy was proposed to apply in multiple-input multiple-output (MIMO) sine on random (SOR) mixed mode vibration test, which is the advanced and intensive test type of VET. As the key problem of the strategy, correlation integral method was applied to separate the mixed signals which included random and sinusoidal components. The feedback control formula of MIMO linear random vibration system was systematically deduced in frequency domain, and Jacobi control algorithm was proposed in view of the elements, such as self-spectrum, coherence, and phase of power spectral density (PSD) matrix. Based on the excessive correction of excitation in sine vibration test, compression factor was introduced to reduce the excitation correction, avoiding the destruction to vibration table or other devices. The two methods were synthesized to be applied in MIMO SOR vibration test system. In the final, verification test system with the vibration of a cantilever beam as the control object was established to verify the reliability and effectiveness of the methods proposed in the paper. The test results show that the exceeding values can be controlled in the tolerance range of references accurately, and the method can supply theory and application supports for mechanical engineering.

Development of a New, High-Power Solar Array for Telecommunication Satellites

Airbus is currently developing the Next Generation Solar Array (NGSA) for telecommunication satellites. It is based on a hybrid array concept which combines a conventional rigid panel array with lightweight, semi-rigid lateral panels. The main figures of merit power/mass and power/volume can be doubled through this concept. Mechanically, the semi-rigid panels are the key new element. Through acoustic testing as well as sine vibration testing in air and in vacuum it was verified that these panels are suitable as cell support in stowed configuration. With the help of finite element modelling it is demonstrated that the semi-rigid panels are compatible with a free deployment. Electrically, the new array is to be equipped with a new generation of 4 junction solar cells with efficiencies above 30%. The increased radiation dose due to electric orbit raising has to be taken into account to arrive at the optimum shielding while still minimizing the array mass. By adjusting the ratio of rigid to semi-rigid panels and through the choice of solar cell type and mass, the NGSA can be tailored in a wide range to needs of a given platform. This is illustrated for the solar array to be flown on the new Airbus platform Eurostar Neo.

ARA MK4 Solar Array Development

The ARA (Advanced Rigid Array) Mk4 solar array development program is conducted under an ESA-Artes contract.In order to enter new markets with recurring potential such as the market for small to medium range Comsats and moreover to remain competitive with its Solar Arrays on existing markets, Airbus DS Netherlands needed to evolve its current product line of ARA Mk3 and FRED to a new generation Solar Array, the ARA Mk4. The main goals of the ARA Mk4 development program are solar array cost and risk reduction, robustness, performance increase and readiness for growth capability.The requirements for the ARA Mk4 solar array are enveloping the needs for a number of intended applications such as EDRS-C, GMP-T, MetOp-SG and Geostar-3. Furthermore the requirements are based on launch with today’s launchers. The EDRS-C program has been the first customer for the ARA Mk4 solar array.The ARA Mk4 solar array has been divided into a number of units such as PVA, Panel Substrates, Yoke, Holddown and Deployment mechanisms and Inter-Panel Harness. These units are developed and qualified before verification at wing assembly level. Wing level tests, including sine vibration and acoustic noise testing, has been performed successfully.In addition to hardware development also the analysis tools, integration approach, qualification status control and documentation generation for recurring projects have been upgraded.The outline of the ARA Mk4 development program, the obtained results and the achieved status with regard to the set goals are presented in this paper.

Random Vibration Analysis for Starter Motor of Three Wheeler Automobile

Automobile industries have prime importance to vibration testing. Sine vibration testing is performed when we have been given with only one frequency at given time instant. Trend to perform random vibration testing has been increased in recent times. As random vibration takes into account all excited frequencies in defined spectrum at known interval of time, it gives real-time data of vibration severities. The vibration severity is expressed in terms of Power Spectral Density (PSD). The consideration in the paper is based on the fact that we will be dealing with only random vibration. Aim of paper is to perform random vibration analysis for starter motor mounted on an engine and also find its transmissibility value.

Experimental study on on-orbit and launch environment vibration isolation performance of a vibration isolator using bellows and viscous fluid

Operation of various actuators on a satellite such as reaction wheels, cryocoolers, etc. produces micro-vibration which may have adverse effects on the performance of high precision payloads. In order to protect the high precision payloads from the vibration disturbances, vibration isolators are often applied in the vibration propagation path. Vibration isolators developed for on-orbit space application should be able to isolate micro-vibration when in orbit, and also withstand severe launch vibration environment. In this paper, on-orbit and launch environment isolation performance of a vibration isolator using bellows and viscous fluid is evaluated. For the on-orbit environment test, a test setup was prepared inside a thermal-vacuum chamber and the transmissibility of the vibration isolator was measured to examine the effects of on-orbit space environment on the isolation performance of the developed isolator. The isolation test performed in a vacuum condition revealed problems caused by the elongation of the bellows due to the pressure difference which were addressed by sealing the viscous fluid inside the bellows at a vacuum condition. The effect of temperature variation on the isolation performance was found to be confined to the narrow frequency region around the isolator's resonant frequency due to the isolator's three parameter configuration. This result implies that the isolation performance of a vibration isolator having temperature dependent damping can be made less sensitive to the temperature variation by implementing three parameter configuration. The developed vibration isolator is designed to survive large deformation without being permanently deformed to guarantee the structural safety of the isolator in the launch environment. The structural safety of the isolation system is evaluated through sine and random vibration and shock tests. The on-orbit and launch environment test results indicate that the developed isolator can provide effective isolation for the small amplitude vibration disturbances on-orbit and also survive the large amplitude vibration during launch without any damage.

Characteristics of spaceborne cooler passive vibration isolator by using a compressed shape memory alloy mesh washer

Cryogenic coolers produce undesirable micro-vibrations during on-orbit operation, which may seriously affect the image quality of high-resolution observation satellites. Micro-vibrations can be easily isolated by mounting the cooler on a vibration isolator with low stiffness to attenuate the vibration transmitted to the satellite structure. However, the structural safety of a cooler supported by an isolator with low stiffness cannot be guaranteed under the much more severe vibration condition of a launch environment. In this study, to guarantee vibration isolation performance in a launch environment while effectively isolating the micro-vibrations from the cooler on-orbit, a new type of passive vibration isolation system by using a compressed shape memory alloy mesh washer was proposed and investigated. The basic characteristics of the isolator were measured in static and free vibration tests of the isolator, and a simple equivalent model of the isolator was proposed. The effectiveness of the isolator design in a launch environment was demonstrated through sine vibration, random vibration, and shock tests.

형상기억합금 메쉬 와셔를 이용한 우주용 냉각기 진동절연기의 발사 진동 및 충격 저감 성능검증

ABSTRACT Micro-vibration induced by on-board equipments such as fly-wheel and cryogenic cooler with me-chanical moving parts affects the image quality of high-resolution observation satellite. Micro-vi-bration isolation system has been widely used for enhancing the pointing performance of observation satellites. In general, the micro-vibration isolation system requires a launch locking mechanism addi-tionally to guarantee the structural safety of mission payloads supported by the isolation system with low stiffness under launch environment. In this study, we propose a passive launch and on-orbit vi-bration isolation system using shape memory alloy mesh washers for the micro-vibration isolation of spaceborne compressor, which does not require the additional launch locking mechanism. The basic characteristics of the isolator were measured in static and free vibration tests of the isolator, and a simple equivalent model of the isolator was proposed. The effectiveness of the isolator design in a launch environment was demonstrated through sine vibration, random vibration and shock tests.

A correlation study of satellite finite element model for coupled load analysis using transmissibility with modified correlation measures

In this paper, a correlation study of satellite finite element (FE) models for coupled load analysis (CLA) using transmissibility and modified correlation measures is reported. CLA is performed with the launch-vehicle company to assess the structural integrity of satellite structure as well as the safety of its payload and electronics as a final verification by investigating the calculated acceleration, gap, and interface loads under launch environment conditions. To increase the accuracy of CLA, the complex FE model has to be validated via FE model updating with the results from dynamic tests, such as sine vibration testing, with proper criteria of correlation. When comparing modal properties obtained by analysis and testing, such as natural frequencies, mode shapes, and frequency response functions (FRFs), transmissibility measured from accelerometers with known input acceleration, but not input force, is used as a reference test data because it is often difficult or impossible to measure excitation force directly in many industrial structures.To match analysis results with the test results showing weak nonlinearity with respect to excitation level, several peaks of acceleration as well as modal properties are taken from transmissibility according to the excitation level, and then the FE model is updated using the sensitivity analysis with several correlation measures, such as frequency deviation error, frequency domain assurance criteria (FDAC), frequency response assurance criteria (FRAC) and modified versions of them to customize the correlation measures for CLA.Finally, it is shown that the proposed approach with transmissibility and the modified correlation measures is quite efficient and reliable for preparing a FE model for CLA, while meeting the standards of many aerospace agencies.