Modal Analysis Method Research Articles

Reducing Sachet Noodle Defects by Applying the Seven Tools and the FMEA Method

The ICBP is a company that produces the noodle’s sachet on a large scale for domestic and international markets. The sachet’s defect of the Regular Special Fried Noodle for the Saudi Arabia market from January up to December 2023 is 2.39%, which is above the company's standard limit. The aim of this research is to determine the types of defects, and to find out the factors that caused them and find out the solutions to minimize the number of defects. Analysis using the seven tools identified that the most dominant defect is swallen laminate, with a percentage of 51% of total defects. By using the Failure Mode and Effect Analysis (FMEA) method, the highest RPN value was obtained at 280 for the machine factor. The recommended solution is to clean up the die lip thoroughly to ensure the condition of the die lip remains clean, to recalculate the need for a Preventive Maintenance schedule and calibration of the die lips based on machine age and machine usage working hours, and at the same time provide SOP and scheduled training for employees to make sure they know how to do the job.

Identification of Nonlinearity in Bolted Beam using ResponseControlled Testing and ForceControlled Testing

Nonlinear phenomena such as super-and sub-harmonics and unstable branches in frequency response functions (FRFs) often occur in slender structures, which are common in the aerospace, civil and wind power domains. The widely used methods of linear modal analysis are invalid for the identification of these phenomena, which play an important role in nonlinear structural analysis as they can significantly affect the behaviour and stability of structures under various excitations. This paper proposes the methodology of Response-Controlled Stepped Sine Testing (RCT) and Force-Controlled Stepped Sine Testing (FCT) to identify nonlinear phenomena in a bolted beam. The bolted beam was excited with two different sets of predefined displacement and force amplitudesto measure the Nonlinear Frequency Response Functions (NLFRFs) of the bolted beam. The measurements were performed with RCT and FCT, using Stepped Sine signals to control the displacement and force amplitudes. The Harmonic Force Surface (HFS) technique was used as means of obtaining the NFRFs. It was found that RCT with HFS successfully identifiedthe nonlinearity that is very similar to the identification results obtained with FCT. In addition, RCT was computationally faster than FCT in identifying nonlinear bolted beams and avoided dealing with jump phenomena. These advantages of RCT and HFS can provide engineers and researchers with a great technique to accurately and efficiently identify nonlinearities in structures.

Risk Identification on Screw Press Machines Using the Failure Mode and Effect Analysis (FMEA) Method on CV.” Rezeki Bersama

CV. Rezeki Bersama is a producer of crude coconut oil (CCO) based in Alus-alus Village, Teupah Selatan District, Simeulue Regency, Aceh. CV. Rezeki Bersama employs 15 people at various production stations, including press machines. In practice, this research uses the Failure Mode and Effect Analysis (FMEA) method to determine the damage that occurred at the press station of the joint rezeki factory. The FMEA approach is used to assess the likelihood of failure in a manufacturing process, determining its severity, frequency of occurrence, and detectability. This study focuses on collecting machine damage data from January 3 to February 3 2024 and evaluating it to determine the Risk Priority Number (RPN) value which will be used to indicate the priority of repairs needed. This research aims to provide recommendations for repair and prevention of damage in the future, as well as increasing the reliability and efficiency of the company's operations.

Enhanced Subspace Iteration Technique for Probabilistic Modal Analysis of Statically Indeterminate Structures

In structural stochastic dynamic analysis, the consideration of the randomness in the physical parameters of the structure necessitates the establishment of numerous stochastic finite element models and the subsequent computation of their corresponding vibration modes. When the complete analysis is applied to calculate the vibration modes for each sample of the stochastic finite element model, a substantial computational expense is incurred. To enhance computational efficiency, this work presents an extended subspace iteration method aimed at rapidly determining the vibration modal parameters of statically indeterminate structures. The essence of this proposed method revolves around efficiently constructing reduced basis vectors during the subspace iteration process, utilizing flexibility disassembly perturbation and the Krylov subspace. This extended subspace iteration method proves particularly advantageous for the modal analysis of finite element models that incorporate a multitude of random variables. The proposed modal random analysis method has been validated using both a truss structure and a beam structure. The results demonstrate that the proposed method achieves substantial savings in computational time. Specifically, for the truss structure, the calculation time of the proposed method is approximately 1.2% and 65% of that required by the comprehensive analysis method and the combined approximation method, respectively. For the beam structure, on average, the computational time of the proposed method is roughly 2.1% of a full analysis and approximately 48.2% of the Ritz vector method’s time requirement. Compared to existing stochastic modal analysis algorithms, the proposed method offers improved computational accuracy and efficiency, particularly in scenarios involving high-discreteness random analyses.

Research on Damage Detection of Dual-Rotor Synchronous Excitation Mine Screen Beams Based on Strain Mode Difference Vibration Mode Analysis.

The frame beam structure of the mine screen, subjected to various excitations, is a critical component of mining machinery. Its stress is intricate, the operational environment is severe, and damage can lead to catastrophic failures resulting in machinery destruction and fatalities. Based on the characterization of the vibration response of mine screen frame beams with varying degrees of damage at the same location and with the same degree of damage but at different locations, this paper develops a method of strain modal difference vibration pattern analysis and damage feature extraction for the detection of structural damage in beams. This method is based on the sensitivity of the sudden change in vibration strain modal difference to small deformations. This method solves the problem of using the conventional structural finite element analysis or experimental modal analysis methods to obtain the displacement mode, intrinsic frequency, and other characteristics, which make it difficult to effectively identify the actual engineering, with the damage conditions of the damage state and damage location of the mine screen frame beam problems. The feasibility and validity of the engineering application of the concept are demonstrated through instances.

A generalized method of power oscillation characteristic analysis for multi‐VSC grid‐connected system

AbstractThe grid‐connection of high‐permeability new energy through voltage‐source converters (VSCs) brings new oscillation risks to the power system, which seriously threatens the stable operation of the system. Therefore, an evaluating method based on modal analysis is proposed to investigate the power oscillation characteristics in a multi‐VSC grid‐connected system. Initially, based on the analogy method, the output admittance model of voltage‐source controlled VSCs (VC‐VSCs) and current‐source controlled VSCs (CC‐VSCs) is established. Subsequently, the output admittance model of a multi‐VSC grid‐connected system is constructed. Then, the modal analysis method is introduced to investigate the power oscillation characteristics of VC‐VSCs and CC‐VSCs, and the influence factors of power oscillation and its variation law are analysed. Next, a sensitivity analysis is also employed, which helps to identify the origin of each oscillation mode and determine the contribution of each component to the power oscillation. Finally, simulation and experiment are carried out to verify the effectiveness of the above analysis method.

Analisis Pengendalian Kualitas Batako di CV. Berkah Pandaan dengan Menggunakan Metode FMEA (Failure Mode and Effect Analysist)

Kholifan fani, Engineering Study Program, Yudharta Pasuruan University Pasuruan, 02 July 2024. Batake Quality Control Analysis, At CV. BERKAH PANDAAN Using the FMEA (Failure Mode and Effect Analysis ) Method. The aim of this research data is to determinan the process of controlling the quality of bricks at CV. Berkah Pandaan using the FMEA (Failure Mode and Effect Analysis) Method. The approaches used are SWOT and FMEA. Failure Mode and Effect Analysis is defined as a method used to identify the causes and consequences of a failure. SWOT is the systematic identification of various factors to formulate company strategy. This analysis is based on logic that can maximize strengths and opportunities, but simultaneously minimize weaknesses and threats. Based on result of this research, the causes of defects that occur at CV. Be identified. BERKAH PANDAAN is caused by two thigs, namely in terms of humans and machiens, form the human perspective it is mosly caused by a lack of work concentration so that the quality of work decreases, this is triggered by working environmental conditions that are less supportive, including room temperatures that are too hot, insufficient lighting. Engine noise that is too loud in terms of the engine usually occurs because the engine is experiencing downtime.

Work Accident Risk Analysis Using Failure Mode and Effect Analysis (FMEA) Method at PT. XYZ

In the production process, the interaction between humans and machines is closely related. From this the higher the risk of accidents along with the higher workload. This study aims to identify the risk of accidents that may arise during the work in progress. In addition, to identify actions that can be taken to reduce these risks. This type of descriptive qualitative research was conducted to assess the risk of work accidents at PT. XYZ. The data used in this study is primary data obtained through interviews using a questionnaire on one of the workers of PT. XYZ. The data were analyzed using the Failure Mode and Effect Analysis (FMEA) method to find the RPN and critical values ​​to find priority risks for action. The results obtained are that there are 4 work objects on the machine being analyzed, namely the stamping machine, lathe, welding machine, and milling machine. Based on the RPN value, it was obtained a value of 264 for a cut hand, 357 for a hand hit by a craft, 148 for a hand exposed to a welding spark, and 371 for a hand-carried by a machine. Based on the highest critical value, a stamping machine was obtained with a value of 66. The suggestion given to anticipate the occurrence of work accidents is by affirming SOPs in the use of Personal Protective Equipment (PPE), as well as workers' understanding of the risks of work accidents and their impacts.

Unsteady flow analysis in a pump as turbine impeller based on proper orthogonal decomposition and dynamic mode decomposition methods

Pump as turbine (PAT) is an efficient, simple, and cost-effective equipment combining pump and turbine and is one of the excellent energy recovery devices. It is helpful to master the flow characteristics of the key component impeller for the further optimization and design of the PAT. To analyze the unsteady flow features in the impeller of a double-suction pump operating as a turbine, numerical simulations were conducted using the shear stress transport (SST) k-ω turbulence model at the designed operating conditions. By utilizing proper orthogonal decomposition (POD) and dynamic mode decomposition (DMD) methods on the unsteady velocity field of a single cycle, the dominant modes up to the fourth order, along with their respective space–time information, can be extracted. The velocity field and vorticity field analysis were performed on the first four modes extracted using two different methods. Additionally, the vortex structures were extracted using the Ω method. The analysis demonstrates that the POD and DMD methods effectively decompose the intricate flow characteristics within the impeller into dynamic–static interference modes, fundamental modes, and dissipative modes. The dynamic–static interference mode is dominant, reflecting the flow characteristics influenced by the stationary components within the impeller. The vortex structure is mainly small tubular vortex and point vortex. The fundamental mode captures the steady flow field characteristics caused by the blade channel geometry. The vortex structure is mainly continuous tubular vortex and the diameter becomes larger. The dissipative mode reflects the flow separation generated on the blades by disturbances from the stationary components. The vortex structure is dominated by point vortex and discontinuous tubular vortex. Comparing the outcomes of the two modal analysis methods shows that the POD method has a distinct advantage in showcasing key changing nodes. In contrast, the DMD method is superior in isolating modes with a single frequency and in determining their stability.

Risk Management of Green Bean Farming Production in Gluranploso Village, Gresik District

Green beans are the most important food crop in Indonesia and production continues to increase to meet domestic demand. However, production is still insufficient due to several risks faced by farmers. This research analyzes the risk management of green bean production in Gluranploso Village using the Coefficient of Variation (KV) and Failure Mode and Effect Analysis (FMEA) methods. The results showed that yield variation was relatively low with a KV value of 17%, indicating good yield stability. The FMEA analysis identified four main sources of risk affecting production: seed aspect with an RPN value of 5.808, weather with an RPN value of 7.04, pests and diseases with an RPN value of 12.936, and technical aspects with an RPN value of 47.88, particularly delays in pest and disease control spraying. In addition, the market aspect is also a source of risk with the largest value in the increase in production input prices at 12.288. These sources require special attention in risk management. The study concludes that the implementation of appropriate risk management strategies, focusing on the identified key risk sources, can help farmers improve yield stability and farm profitability. These strategies include improving seed quality, mitigating weather risks, controlling pests and diseases, and improving technical procedures in cultivation and market risks. Thus, effective risk management can be key in increasing the productivity and sustainability of green bean farming in Gluranploso village.

Quality improvement using lean six sigma in air conditioning products

Air Conditioners (AC) are essential electronic products for residential and industrial buildings in tropical countries or during warm weather in general. The penetration ratio of electronic Air Conditioners (AC) has been increasing every year. Data collection and processing were conducted directly by the author through observation, measurement, and calculation on the heat exchanger production of Air Conditioners (AC). In the production cost of Air Conditioners (AC), the heat exchanger accounts for the second highest cost after the compressor making up 19% of the total cost. The high cost is caused by pipe leaks, with a percentage of 73.7%. This research aims to analyze the improvement of Air Conditioner (AC) production quality using the Six Sigma method. The defect rate in the heat exchanger, evaluated through the Define, Measure, Analyze, Improve, Control (DMAIC) method originating from Six Sigma, was found to be 1,144.8 defects per million opportunities. Further analysis was conducted with the Failure Tree Analysis (FTA) and Failure Mode and Effect Analysis (FMEA) methods. This research was conducted at XYZ company by conducting interviews and observations for 3 months. FMEA and FTA analysis resulted in the top two failure risks based on the Risk Priority Number (RPN): flaring diameter too big and unstable brazing skill. In the manual brazing process, it was found that work by operators with level A certification produced 9% below standard outcomes. An improvement was obtained by changing the punch flaring size to 8.5mm and conducting skill certification and training for brazing operators. The results of the proposed improvement implementation led to a reduction in the DPMO value to 403.35, equivalent to a decrease of 64.7%. The defect ratio in production decreased by 38.1%, exceeding the previous target of 26.2%, equivalent to $31.96/month/unit. The results of this study are horizontal, allowing the implementation of improvements made in the heat exchanger production process to be expanded to other cooling electronic production processes.

Negative impact of vibration on process pipelines of a compressor station with electrically driven gas pumping units

Relevance. In gas industry, the amount of equipment that has outlived its intended service life is increasing every year. In accordance with the law “On Industrial Safety of Hazardous Production Facilities,” compressor stations are dangerous objects, the reliable operation of which largely determines the condition of main gas pipelines. Technological pipelines of a compressor station are important objects of this system. They are subject to strict requirements due to the action of static and dynamic loads on them. Reliability of compressor stations is based on the results of a study of the condition of the object and the main factors affecting increased wear of equipment. The solution to wear problem is timely monitoring of equipment, in particular level measurement and determining the causes of pipeline vibrations using vibration diagnostics methods, and frequency and modal analysis methods. Aim. To study the causes of increased dynamic loads on the technological piping that arise during the operation of electric and gas pumping units at a compressor station using vibration monitoring methods. Methods. Vibration monitoring methods to analyze the causes of increased vibration values in the process piping of a compressor station with an electric gas pumping unit. Results and conclusions. The authors have measured vibration in a wide frequency band and assessed the technological condition of the main equipment of the compressor station with EGPA-6.3/8200-56/1.44-R based on the regulatory documentation STO Gazprom 2-2.3-324-2009. The main frequencies of the root-mean-square value of the vibration velocity, at which the highest vibration values were observed, were identified, and a modal analysis was performed using ANSYS software. Based on the results of natural studies and modal analysis, it was concluded about the occurrence of resonant high-frequency oscillations, multiple of the rotor rotation frequency.

Analysis of active impedance characteristics and harmonic deterioration of multiple grid connected inverters considering nonlinear factors

AbstractThe harmonic problems caused by non‐linear factors of the grid connected inverter (GCI) system are more complicated, including both non‐characteristic harmonics emitted by the dead‐time and the changes in harmonic impedance characteristics. Harmonics interact with the changing impedance, and even cause harmonic amplification and resonance. The harmonic deterioration of the multiple GCIs system is serious. To analyse the mechanism and way of harmonic deterioration in grid‐connected system caused by nonlinear factors, the active impedance models of single inverter and multiple GCIs system including dead‐time effect and digital control delay are established first. In view of this, the influence mechanism of non‐linear factors on system stability is explored. The improved modal analysis method is used to traverse the network series parallel resonance caused by nonlinear factors. The results show that both the dead‐time effect and digital control delay reduce phase margin of the system, resulting in the resonant frequency shift and the resonant peak increase. When the harmonic excitation source interacts with the complex network under the influence of nonlinear factors, it will lead to further deterioration of harmonics. Finally, based on the MATLAB and RT‐LAB hardware‐in‐the‐loop simulation platforms, a multiple GCIs system model is built to verify the correctness of the established active impedance model and harmonic deterioration analysis.

A strain transmissibility-based analysis approach for operational modal of concrete dam under nonstationary excitation

The transmissibility-based operational modal analysis (TOMA) method is attracting more attentions due to its relaxation of assumptions about excitation properties, making accurately identifying the modes of actual engineering structures possible. However, in specific application on distributed vibration responses of huge hydraulic structures excited by broad-spectrum non-stationary earthquake, more proper selections of data segmentations on two dimensions (along time or spatial axis) are needed. Based on the concept of distributed vibration sensing optical fiber strain transmissibility, the operational modal analysis model based on single reference and poly references transmissibility under the strain format and the corresponding solutions of model and modal parameters are studied. A false mode elimination method combined with the continuity of spatial distribution of optical fiber measurements, a response sequence set optimization method that comprehensively consider amplitude/PSD non-stationarity, and the principle about how to select (non) reference points (sets) considering the spatial distribution of measurement signal-to-ratio are further developed. The case study shows that the proposed combined method could improve the modal parameter identification accuracy of concrete dams under broad-spectrum non-stationary excitation, and the distributed optical fiber vibration sensing technology can provide a rich (non) reference point (set) selection combination for this method.

Determination of the Modal Parameters of the Historical Elevated Water Tank Using Experimental and Numerical Methods

Determining the modal parameters of historical buildings is crucial for understanding their dynamic behavior, which is essential for their preservation and safety for future generations. Experimental and numerical studies are commonly used to characterize modal properties such as natural frequencies and mode shapes. Experimental studies typically employ the operational modal analysis method, while numerical studies employ the finite element method. Vibration measurements of the structure under various environmental conditions, including wind and traffic, were used to determine the modal parameters. However, discrepancies often arise between modal parameters obtained from experimental research and those assessed by finite element models, primarily due to unknown factors like boundary conditions and material properties. The purpose of this study was to measure the vibrations of a historic elevated water tank a 150-year history under ambient conditions to determine its modal characteristics. Comparing the modal parameters obtained from numerical and experimental investigations revealed that the water tank's finite element model requires updating to align with the findings of the experimental modal study. Using the updated finite element model in future evaluations or assessments of the structure can lead to a better understanding of the behavior of the structure.

Analysis and optimization of the dynamic response characteristics of aircraft cargo rack

In order to effectively achieve the optimization design of the aircraft cargo rack, based on finite element modal simulation, the structure was redesigned and analyzed using two schemes of surrogate model size optimization and topology optimization, ensuring the strength requirements while improving the natural frequency and reducing the weight. According to the modal shape of vibration, additional bridge structures were added at the weak points to improve the dynamic stiffness of the structure. According to the optimization design requirements, the response surface function was constructed, and the particle swarm optimization algorithm was applied in the size optimization and surrogate model solution. A multi-objective optimization model was established for flexibility and low-order natural frequencies, and topology optimization was carried out in HyperWorks. The structural dynamic modification of the topology optimization model was performed using the modal strain energy analysis method. The research results show that both optimization methods can achieve good lightweight design. The static performance of the optimized structure is stable, and the overall modal frequency is improved.

Optimization of reduction gear in anchor winch based on modal analysis

In order to achieve more scientific design of the reduction gear and reduce material waste, pre-stressed modal analysis method was combined with multi-objective optimization algorithm to optimize the structure of the reduction gear basic body. The model was simplified and parameterized and the maximum stress and equivalent stiffness under different parameter size combinations were obtained through finite element analysis. Separately, genetic clustering method, neural network method, and Kriging method were used to construct the response surface function. Through error verification and comparison, it was found that the Kriging method was more suitable for the gear model. In the design of variable extremum search, multi-objective genetic algorithm and sequential quadratic programming were compared and analyzed. The results show that the mass of the gear can be reduced by 39.9 %, while the maximum stress remains unchanged, the equivalent stiffness is not reduced, and a good optimization design effect is achieved.

Optimalisasi Preventive Maintenance Ground Power Unit pada Perawatan Pesawat Udara di PT. IAA AMO Menggunakan Metode FMEA

High operational costs and downtime risks can affect industry efficiency making equipment maintenance optimization an urgent need. PT. IAA AMO, as a manufacturing industry in the field of aircraft maintenance, faces significant challenges with the low reliability of Ground Power Unit (GPU) engines which only reaches 86%. This has led to an increase in the company's operating costs. The purpose of this study is to optimize Preventive maintenance on the Ground Power Unit (GPU) in aircraft maintenance at PT. IAA AMO using the Failure Mode and Effect Analysis (FMEA) method. The results show that the MTTF of the GPU is 311 hours, while the MTBF is 373 hours. To prevent sudden breakdowns, preventive maintenance is recommended every 311 hours for non-repairable components and 373 hours for repairable components. This research offers a more effective maintenance strategy to improve GPU reliability and lower operational costs. This research results in more effective maintenance planning, which not only minimizes downtime and operational costs, but also improves the overall reliability of the GPU machine. With the implementation of FMEA methods and the right preventive maintenance strategy, companies can anticipate breakdowns early, extend engine life, and ensure smooth operations in support of aircraft maintenance.

Observation and Prediction of Instability due to RD Fluid Force in Rotating Machinery by Operational Modal Analysis

In recent years, as rotating machinery has become smaller and more efficient, various types of shaft vibration problems have arisen. Failure of rotating machinery may lead to major accidents and infrastructure shutdowns. Therefore, to prevent failures of rotating machinery, there is a growing need for the vibration analysis technology at the design stage and condition monitoring during operation stage. One of causes of the shaft vibration problems in rotating machinery is the rotordynamic (RD) fluid force acting on fluid elements such as journal bearings, seals, turbine blades, and so on. RD fluid force has a significant effect on the stability of rotating machinery and can destabilize the system. In recent years, operational modal analysis (OMA) methods, which identify modal parameters based on the measured data of a machine's operational condition, have been investigated in the condition monitoring. In this paper, the estimation of the modal parameters of rotating machinery using OMA from only the time history response of displacement data and, in particular, the prediction of the destabilization of rotating machinery caused by RD fluid force are investigated. As a result, the modal parameters are well estimated and, in particular, the destabilization of one mode due to RD fluid force is predicted and explained. The results are in good agreement with the results of the eigenvalue analysis of the original system, and the method is validated. Furthermore, the proposed method is applied to experimental data of the system destabilized by fluid force. The change in stability with rotational speed is observed, and the characteristics of the mode toward destabilization are confirmed. The results show the validity of OMA's predictions of destabilization in the experiments.

Initial monitoring of a six-story lightweight timber frame building under different environmental conditions

AbstractThis study presents a comprehensive investigation of the dynamic behavior of a six-story lightweight timber frame building through periodic and continuous ambient vibration tests. Seasonal changes in temperature and relative humidity can influence the dynamic response of timber buildings, by affecting stiffness, strength, and connection properties due to changes in moisture content. Systematic tests were performed from October 2022 until May 2024 to identify natural frequencies, damping ratios, and mode shapes of the building using five battery-driven data acquisition units equipped with 15 uni-axial accelerometers. Two different only-output frequency and time domain Operational Modal Analysis (OMA) methods were used to evaluate the dynamic properties of the building. Additionally, the building has been continuously monitored with temperature and humidity sensors since its construction. Results obtained from the periodic measurements highlighted the need for a permanent system to capture the transient changes in the modal parameters. A complementary permanent system to record the accelerations at the roof level was installed in May 2024. The modal parameters from in situ measurements were compared with those obtained from the Finite Element (FE) model of the structure. The FE model, calibrated through a multi-stage approach, incorporating non-structural elements, and varying imposed loads, showed good agreement with experimental data. Comparative analysis of the results obtained under different temperature and humidity conditions showed the effect of the environmental conditions on the building dynamics properties, for both periodic and permanent measurements. This study highlights the importance of continuous monitoring and detailed FE modeling in understanding the dynamic properties and long-term structural behavior under varying conditions. This information can be used to ensure that the building meets safety and performance requirements and to identify potential issues that may need to be addressed during the design and maintenance phases.