Random Vibration Loading Research Articles

Fatigue Life Based Study of Electronic Package Mounting Locations on Printed Circuit Boards Subjected to Random Vibration Loads

Fatigue Life Based Study of Electronic Package Mounting Locations on Printed Circuit Boards Subjected to Random Vibration Loads

Fatigue life sensitivity research for electric driving system in driving load cases and random vibration load cases

In this paper, the fatigue characteristics of the electric drive system in driving load cases and random vibration load cases are analyzed numerically and experimentally. The fatigue life of the driving system under these two load cases is analyzed by using the time domain method and frequency domain method respectively. The results show that the damage of rotating parts (gear and bearing) mainly occurs in driving load cases, and the damage of gear and bearing in the driving load cases is 71.78% and 43.46% respectively. Fixed components (housing and suspension support) have certain damage in driving load cases and random vibration load cases, and the damage is greater in driving load cases. The damage of housing and suspension support in driving load cases is 10.6% and 0.167% respectively; the damage under random vibration load cases is 1.32 × 10−11 and 3.12 × 10−11 respectively. Based on the above conclusions, it is suggested that the driving load case tests for electric driving system are necessary, but it is not necessary to do random vibration tests only for electric driving system, or the number of random vibration tests can be reduced. This not only ensures the reliability of the components, but also helps to reduce the test cost.

Reliability modeling of pre-stressed composite structures subject to interlayer slip failure under multi-axial random impact and vibration loads

A time-dependent reliability model for pre-stressed metal/polymer/metal composite structures subject to interlayer slip failure is developed in this study, allowing for predicting the probability of failure of the whole structure under multi-axial random multi-peak impact loads and transport vibration. A multi-Gaussian envelope model with uniform modulations is proposed to model random multi-peak impact loads, and the inverse sampling method is employed to model random transport vibration. An interlayer slip physics model is developed based on the contact surface friction mechanism under multi-axial vibration load and the stress-relaxation constitutive model. By implementing the interlayer slip physics model in the finite element method framework via the user-material routine, the geometry effect of the structure can be dealt with, and the reliabilities at an arbitrary location of the structure can be obtained. The proposed method is demonstrated using engineering examples. The results show that the proposed reliability assessment method provides a viable and systematical procedure of computing the time-dependent reliability of composite structures as a whole under multi-axial impact loads and vibrations.

A hybrid frequency‐time domain life prediction method based on the critical plane theory

AbstractThis study proposes a multiaxial rainflow counting method to realize simultaneous counting of four‐channel data. The power spectral density (PSD) expressions of stresses and strains in different planes are derived according to multiaxial theories to address the fatigue problems under random vibration loading. This study takes the plane with maximum variance of shear strain PSD as the critical plane and proposes a hybrid frequency‐time domain life prediction method for calculating the life under random vibration loading in combination with the proposed new multiaxial rainflow counting method. Both the feasibilities of the proposed multiaxial rainflow counting method and hybrid frequency‐time domain life prediction method are verified by using the multiaxial fatigue experimental results of 6061‐T6 and 7075‐T6 aluminum alloys under random loading. Meanwhile, the calculation results and efficiencies of the proposed life prediction method are summarized, and the prediction effects of the different multiaxial fatigue models are evaluated, and different rainflow counting methods are compared.

Multi-sensor data fusion reconstruction method for vibration dynamic responses of aerospace structures

The dynamic responses of key locations are important inputs for the life and reliability assessment of spacecraft structures. Due to the limited sensing resources, most critical responses are difficult to measure directly. A structural dynamic response reconstruction method is necessary. The responses of target locations can be reconstructed based on the empirical mode decomposition (EMD) of measured signals and the modal superposition. However, the structural modal information contained in the measured signal of a single sensor is limited, affecting the reconstruction accuracy. In this paper, a response reconstruction method based on multi-sensor data fusion is proposed. It is applied to a main load-bearing structure of a spacecraft and its typical components to verify its strain response reconstruction effect under random vibration loads. The experimental results show that multi-sensor data fusion improves the strain reconstruction accuracy. The maximum reduction in reconstruction error is from 8.7% to 1.3%. The reconstruction accuracy is further improved with the increase in the number of sensors. The optimal weighted fusion strategy for this problem is the weights defined by the Euclidean distance (EUC) or the dynamic time warping distance (DTW). The fusion results show a better performance with the increase in the power of the defined distance. The proposed multi-sensor fusion method improves the reconstruction accuracy via supplementing structural information to each other and eliminating the instability of single measured signals. More accurate dynamic responses via reconstruction reduce the large input uncertainty in life prediction and lay the foundation for building structural digital twins and managing structural health more effectively.

Characterization of Behavior of Lithium Ion Battery Under Vibration and Shock Conditions

Electric vehicles are being developed to address environmental issues such as air pollution caused by vehicles that use fossil fuels. As a result, the efficiency and performance of the battery, which is a crucial component of an electric vehicle, have become increasingly important. Research on the electrical behavior and heat of the battery is currently being actively conducted. However, with the improvement of battery efficiency and the increase in mass production, safety issues have arisen.Numerous studies are being conducted on battery safety, such as thermal runaway resulting from the deformation and failure of battery components, including the cathode and anode, caused by loads acting on the battery. Recently, research on stress factors caused by random vibrations and shocks that reflect actual vehicle operating conditions has made significant progress. For instance, Brand et al. conducted random vibration and shock tests based on the UN 38.3 standard test, evaluating durability based on the increase in resistance that occurs during the test1). Similarly, Berg et al. tested cylindrical cells with random profiles, according to the SAE J2380 standard and an even more severe profile2). After the test, they mainly observed the deformation of the tab, rather than the jellyroll of the battery. Yun et al. created a numerical model with the Representative Volume Element (RVE) model at the module level, obtaining the effective elastic modulus from the RVE model of the cell level and applied it to the module, so that the behavior of the jellyroll was not described at the cell level3). However, previous studies have mainly analyzed battery degradation caused by vibration and shock tests based on electrical characteristics. Hence, further research on damage and numerical models of battery cell levels that cause degradation according to random vibration and shock tests is required.In this study, anode, cathode, and separator of a pouch cell were prepared in form of a rectangular specimen with notch to conduct vibration and shock tests using the UN 38.3 standard test. The three battery cell components were stacked on a vibration jig, as in a real pouch cell. Scanning electron microscope (SEM) was used to investigate whether a fracture like crack occurred due to a vibration test near the notch of the specimen with a. Additionally, a numerical model for the pouch cell was constructed using a representative sandwich (RS) model4), and the predicted fracture behavior of the battery components according to the vibration and shock test was analyzed. The RS model provided a simplified representation of the internal structure of a battery cell, and the mechanical parameters required to build the RS model were obtained through tensile tests of battery cell components. Brand, Martin J., et al. "Effects of vibrations and shocks on lithium-ion cells." Journal of Power Sources 288 (2015): 62-69.Berg, Philipp, et al. "Durability of lithium-ion 18650 cells under random vibration load with respect to the inner cell design." Journal of Energy Storage 31 (2020): 101499.Jin Chul Yun. "Study on mechanical behavior of lithium ion battery using multi-scale analysis.". (2017). Pohang University of Science and Technology, PhD dissertationZhang, Chao, et al. "A representative-sandwich model for simultaneously coupled mechanical-electrical-thermal simulation of a lithium-ion cell under quasi-static indentation tests." Journal of Power Sources 298 (2015): 309-321.

Complete ensemble empirical mode decomposition with adaptive noise for dynamic response reconstruction of spacecraft structures under random vibration

The dynamic responses of key regions are critical inputs for the structural life estimation of spacecraft. Response reconstruction methods are needed for structural locations where sensors are not placed due to resource limitations. In this paper, a reconstruction method based on complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN) is proposed. CEEMDAN can eliminate the mode-mixing phenomenon of traditional empirical mode decomposition (EMD) during signal decompositions to improve the reconstruction accuracy. The proposed method is applied to the reconstruction of acceleration and strain responses at critical locations of a load-bearing structure under sinusoidal and random vibration loads. Numerical and experimental validation are carried out. The numerical results show that the reconstructions are almost unaffected by the selected white noise levels of CEEMDAN and the locations of measured and targeted points. The experimental results show that compared with traditional EMD, the reconstruction accuracy of CEEMDAN is improved by a maximum of 79.94% with almost no additional computational cost. The proposed reconstruction method shows efficiency and accuracy for a wide range of applications.

Structural Design of Planar Synthetic Aperture Radar (SAR) Antenna for Microsatellites

This paper presents the structural design of a planar synthetic aperture radar (SAR) antenna applied to a microsatellite. For micro-satellite applications, the SAR antenna structure must be lightweight, flat, and designed to withstand the launch environment. To satisfy these conditions, our novel antenna structure was designed using aluminium (AL) alloy. Structural analysis was performed for quasi-static load, random vibration, and shock load to verify its robustness in the launch environment, and the results are presented here.

Study on Dynamic Characteristics of the Typical Components of Ceramic Matrix Composites

In this paper, the typical components of ceramic matrix composites are taken as the research object, the modal test and vibration test are carried out, and the frequency and strain response of the typical components of ceramic matrix composites under random vibration load is understood. The connection strength test is carried out after the typical components of ceramic matrix composites have completed the vibration test. The influence of the vibration environment on the connection strength of typical components of ceramic matrix composites was studied.

Effect of Heat Treatments and Carbon Content on the Damping Properties of Structural Steel

Low- and medium-carbon structural steel components face random vibration and dynamic loads (like earthquakes) in many applications. Thus a modification to improve their mechanical properties, essentially damping properties, is required. The present study focuses on improving and developing these properties, significantly dampening properties, without losing the other mechanical properties. The specimens used in the present study are structural steel ribbed bar ISO 6935 subjected to heating temperatures of (850, 950, and 1050) ˚C, and cooling schemes of annealing, normalizing, sand, and quenching was selected. The damping properties of the specimens were measured experimentally with the area under the curve for the loading and unloading paths experienced from the tensile test. Considering the effect of different parameters on the damping properties, such as heat treatment temperatures, cooling rates, and carbon content, the results show that the damping properties in the annealing process at different temperatures have interesting damping properties, among other processes. Also, the highest damping energy for the annealing cooling scheme was attained at a heating temperature of 1050 ˚C, irrespective of the carbon content. Finally, better damping properties for the medium carbon content of (0.299%C) is achieved for all types of heat treatment process compared with a low carbon content of (0.188% C); and, in general, with increasing carbon content from medium to low, steel response to heat treatment increases and better damping properties are obtained.

Random vibration-based virtual fatigue test for large-scale welded structures using frequency-domain structural stress method and its application to traction transformers

PurposeThis paper aims to present an engineering computational method for fatigue life evaluation of welded structures on large-scale equipment under random vibration load.Design/methodology/approachBased on a case study of the traction transformers, virtual fatigue test (VFT) was proposed via numerical simulation approach. Static analysis was conducted to identify the risky zone and then dynamic response of the risky welds under random vibration load was calculated based on frequency-domain structural stress method (FDSSM) theory, life distribution and associated survivability at various locations of the structure were obtained. Structural modification was finally performed according to the evaluation results. Moreover, experimental test was carried out and compared with the virtual test result.FindingsBy applying the virtual test, fatigue life of the complex welded structures on large-scale equipment can be accurately and efficiently obtained considering dynamic effect under random vibration load. Meanwhile, risky welds can be directly determined and targeted modification scheme can be accordingly concluded. Validity of the VFT result was proved by comparing with the experimental test.Originality/valueThe proposed method can help obtain equivalent structural stress and fatigue life distribution of the welded structure at any position with various survivability and make quantitative evaluation on the life-extending effect of the structural modification. This method shows significant cost and efficiency advantages over experimental test during design stage of the large-scale structures in numerous manufacturing industries.

The Reliability of the Complex Components under Temperature Cycling, Random Vibration, and Combined Loading for Airborne Applications

The electronic devices suffer great vibration and temperature fluctuation in an airborne environment, which has been always a big challenge for reliability design. In this paper, the reliability of the complex electronic components for airborne applications under a thermal cycling test, random vibration and combined loading has been investigated by experiment tests and finite element simulation. The fatigue life and failure location under different loadings have been compared and discussed, respectively. The results indicated that the combined fatigue life was much shorter than a single-factor experiment. The failed solder joints mostly appeared at the interface between the solder and the copper pad on the component side and the location was at the corner for all three harsh environment tests. Nevertheless, several differences could be observed. For temperature cycling, all the specimens failed due to the increase in daisy chain resistance rather than the open circuit for the combined loading test. That is because the degeneration of the solder caused by temperature variation led to lower stress levels and fatigue life. Moreover, the pins fractured at the welding regions have been observed. The modified Coffin—Manson model, Miner’s linear fatigue damage criterion and Steinberg’s model and rapid life-prediction approach were used to predict the fatigue life under temperature cycling, random vibration and combined loading, respectively. With these methods, the accurate numerical models could be developed and validated by experiment results. Thanks to the simulation, the design time could be effectively shortened and the weak point could be determined.

A dynamic-static coupling topology optimization method based on hybrid cellular automata

To improve the ability of the structure to resist static load (SL) and random vibration load (RVL) and prolong the fatigue life, a random vibration topology optimization method (RVTOM) and dynamic-static coupling topology optimization method (DSTOM) are proposed. RVTOM can directly use RVL for topology optimization, avoiding the huge workload caused by gradient information calculation. DSTOM combines the analytic hierarchy process (AHP) and hybrid cellular automata (HCA), and comprehensively considers SL and RVL in topology optimization. The cantilever beam example shows that the SL topology is challenging to resist random vibration load, and the equivalent load cannot replace the RVL for structural topology. Under random vibration excitation, the fatigue life of RVTOM and DSTOM models increased by 32.98% and 24.35%. The control arm example shows that both models have obtained infinite life. The RVTOM model is reasonable, and the load path obtained enhances the ability of the structure to resist random vibration loads and prolongs the fatigue life. DSTOM model can form a load path to fight SL and RVL effectively.

Failure analysis of an aeroengine intermediate case splitter

The intermediate case splitter (splitter) is a kind of thin-walled welded component installed on the aeroengine. During the service of the aeroengine, the crack initiation and growth occurred on the weld joints of the splitter, which seriously threatens the safe operation of the aeroengine. In this study, the fracture morphology characteristics of the crack surface are analyzed in details by scanning electron microscope (SEM), based on the observation of the macro crack of the splitter. The results show that the cracks always appear in the welding zone at the edge of the outer panel of the splitter. The fracture morphology analysis shows that there are obvious fatigue striations in the stable crack growth zone. The microstructure defects such as pores and lack of fusion formed by welding are the direct causes of the fatigue failure of the splitter. In addition, the stress analysis of the splitter under random vibration load shows that the stress concentration in the V-shape slot of the splitter can promote the initiation of fatigue cracks.

Effects of interface cracks on reliability of surface mount technology interconnection in service environment

PurposeSurface mount technology (SMT) is widely used and plays an important role in electronic equipment. The purpose of this paper is to reveal the effects of interface cracks on the fatigue life of SMT solder joint under service load and to provide some valuable reference information for improving service reliability of SMT packages.Design/methodology/approachA 3D geometric model of SMT package is established. The mechanical properties of SMT solder joint under thermal cycling load and random vibration load were solved by 3D finite element analysis. The fatigue life of SMT solder joint under different loads can be calculated by using the modified Coffin–Manson model and high-cycle fatigue model.FindingsThe results revealed that cracks at different locations and propagation directions have different effect on the fatigue life of the SMT solder joint. From the location of the cracks, Crack 1 has the most significant impact on the thermal fatigue life of the solder joint. Under the same thermal cycling conditions, its life has decreased by 46.98%, followed by Crack 2, Crack 4 and Crack 3. On the other hand, under the same random vibration load, Crack 4 has the most significant impact on the solder joint fatigue life, reducing its life by 81.39%, followed by Crack 1, Crack 3 and Crack 2. From the crack propagation direction, with the increase of crack depth, the thermal fatigue life of the SMT solder joint decreases sharply at first and then continues to decline almost linearly. The random vibration fatigue life of the solder joint decreases continuously with the increase of crack depth. From the crack depth of 0.01 mm to 0.05 mm, the random vibration fatigue life decreases by 86.75%. When the crack width increases, the thermal and random vibration fatigue life of the solder joint decreases almost linearly.Originality/valueThis paper investigates the effects of interface cracks on the fatigue life and provides useful information on the reliability of SMT packages.

A Simple Life Prediction Formula for Electronic Equipment Solder Joint Fatigue Design Under Random Vibration Loading in Spacecrafts

A Simple Life Prediction Formula for Electronic Equipment Solder Joint Fatigue Design Under Random Vibration Loading in Spacecrafts

Stress analysis and optimization of pop package under random vibration loading

Stress analysis and optimization of pop package under random vibration loading

Fatigue fracture failure investigation of splitter in engine intermediary casing

The splitter fairing welded by sheet metal of stainless steel was installed in the aircraft engine intermediate case. Under operation load, cracks initiated and propagated along the welded seam in the splitter fairing, which seriously threatens the safe operation of the engine. In this work the cracks in the splitter fairing were detected, and the morphological characteristics of the crack surface were analyzed in detail using a scanning electron microscope (SEM). The cracks in the splitter fairing were initiated from the edge of the weld seam, which is the assembly slot for the splitter. The microstructure analysis of the crack initiation zone confirmed that the microstructure defects such as false welding and oxidation are the direct causes of the fatigue failure of the splitter. Mechanical analysis of splitter fairing under random vibration using the finite element method was performed to confirm that the crack initiated at the stress concentration zone during random vibration load.

Performance Investigation of Superplastic Shape Memory Alloy-Based Vibration Isolator for X-Band Active Small SAR Satellite of S-STEP under Acoustic and Random Vibration Environments

In a launch environment, all satellites are subjected to severe random vibration and acoustic loads owing to rocket separation, airflow, and injection/combustion of the fuel. Structural vibrations induced by mechanical loads cause the malfunction of vibration-sensitive components in a satellite, leading to failures during the launch process or an on-orbit mission. Therefore, in this study, a shape memory alloy-based vibration isolator was used on the connection between the launch vehicle and satellite to reduce the vibration transmission to a satellite. The vibration isolator exhibited a high performance in the vibration isolation, owing to the dynamic properties of super-elasticity and high damping. The vibration-reduction performance of the vibration isolator was experimentally verified using random vibration and acoustic tests in a structural thermal model of the satellite developed in the synthetic aperture radar technology experimental project. Owing to the super-elasticity and high attenuation characteristics of the vibration isolator, it was possible to significantly reduce the random vibration of the satellite in the launch environment. Although the mechanical load of the acoustic test mainly excited the antenna on the upper side of the satellite rather than the bottom side, the results of the acoustic test showed the same trend as the random vibration test. From this perspective, the vibration isolator can contribute to saving the costs required for satellite development. These advantages have made it possible to develop satellites according to the new space paradigm, which is a trend in the space industry worldwide.

Numerical simulation and validation of MWCNT-CFRP hybrid composite structure in lightweight satellite design

Aluminum alloy is generally used in electronic housings of satellites in space avionics due to its remarkable mechanical, thermal, electrical, and radio-frequency shielding properties. This paper proposes a design for a lightweight multi-functional electronic housing made from plastic containing multi-wall carbon nanotubes (MWCNT) composite material. The structural design of housings was validated against a set of boundary conditions and requirements of launch and space environments as prescribed by European Cooperation for Space Standardization (ECSS) standards. The proposed concept for lightweight composite housing was designed with special emphasis on reducing machining operations. The composite housing offers a mass saving of ∼25 % over a typical aluminum housing with similar mechanical performance in the three orthogonal directions. The modal frequency is greater than 100 Hz qualifying the design requirement for satellite electronic housings. Under sinusoidal vibration loads, the structure shows no noticeable excitation in acceleration response graph, indicating no resonance in low-range frequencies from 5 to 100 Hz. Maximum stresses obtained from Quasi-static and random vibration loads are within the tensile strength limit in the three orthogonal directions. In addition, maximum deflection observed in electronic printed circuit boards is within the 1 mm design requirement.