CERES :: Browsing by Author "He, Feiyang"

Browsing by Author "He, Feiyang"

Now showing 1 - 20 of 20

Open Access
Analysis of the self-healing capability of thermoplastic elastomer capsules in a polymeric beam structure based on strain energy release behaviour during crack growth
(MDPI, 2023-08-12) Almutairi, Mohammed Dukhi; He, Feiyang; Alshammari, Yousef Lafi; Alnahdi, Sultan Saleh; Khan, Muhammad Ali
The objective of this study was to investigate the elastic and plastic responses of 3D-printed thermoplastic elastomer (TPE) beams under various bending loads. The study also aimed to develop a self-healing mechanism using origami TPE capsules embedded within an ABS structure. These cross-shaped capsules have the ability to be either folded or elastically deformed. When a crack occurs in the ABS structure, the strain is released, causing the TPE capsule to unfold along the crack direction, thereby enhancing the crack resistance of the ABS structure. The enhanced ability to resist cracks was confirmed through a delamination test on a double cantilever specimen subjected to quasi-static load conditions. Consistent test outcomes highlighted how the self-healing process influenced the development of structural cracks. These results indicate that the suggested self-healing mechanism has the potential to be a unique addition to current methods, which mostly rely on external healing agents.
Open Access
Dynamic response of 3d-printed acrylonitrile butadiene styrene (abs) damaged structure under thermo-mechanical loads.
(Cranfield University, 2021-09) He, Feiyang; Starr, Andrew; Khan, Muhammad Ali
Fused deposition modelling (FDM), as the most widely used additive manufacturing (AM) process, has great potential for various applications. The structures manufactured with the FDM technique has the potential to be used in a variety of complex working environments, such as the coupled thermo- mechanical loads. The coupled thermo-mechanical loads can likely lead to fatigue cracking swiftly in structures till the catastrophic failure. Therefore, it is critical to research the fatigue crack behaviour in FDM structures. This behaviour is mainly responsible for the change of structural stiffness and hence can influence the dynamic response of the structure under the mentioned loads. The measurement of the structural dynamic response can give us an idea of the severity due to crack growth in an in-situ manner. This thesis mainly aims to investigate the dynamic response of the cracked FDM structures under thermo- mechanical loads. The relationship between the coupled loads, crack propagation and dynamic response is developed analytically and later validated experimentally. This research has improved the existing torsional spring model, which can represent the crack depth more accurately and hence estimated the fundamental frequency of the selected structure with an up to around 20% to 120% reduced error in the case of deep cracks. Furthermore, the analytical relationship between the structural displacement amplitude and crack depth and location was modelled for the very first time in the presence of the crack breathing effect. Extensive experimentation is performed to validate the developed analytical relationship and its related theory. The fatigue crack growth of FDM ABS beams under thermo-mechanical loads with varying printing parameters is also investigated. The optimal printing parameters combination (X raster orientaion, 0.8 mm nozzle size, 0.15 mm layer thickness) is determined. The underlying reasons behind the experimental data are analysed. The outcome of this optimisation can help manufacturers to print long-life and crack resistant printed structures.
Open Access
Effect of 3D printing process parameters on damping characteristic of cantilever beams fabricated using material extrusion
(MDPI, 2023-01-04) He, Feiyang; Ning, Haoran; Khan, Muhammad
The present paper aims to investigate the process parameters and damping behaviour of the acrylonitrile butadiene styrene (ABS) cantilever beam manufactured using material extrusion (MEX). The research outcome could guide the manufacture of MEX structures to suit specific operating scenarios such as energy absorption and artificially controlled vibration responses. Our research used an experimental approach to examine the interdependencies between process parameters (nozzle size, infill density and pattern) and the damping behaviour (first-order modal damping ratio and loss factor). The impact test was carried out to obtain the damping ratio from the accelerometer. A dynamic mechanical analysis was performed for the loss factor measurement. The paper used statistical analysis to reveal significant dependencies between the process parameters and the damping behaviour. The regression models were also utilised to evaluate the mentioned statistical findings. The multiple third-order polynomials were developed to represent the relation between process parameters and modal damping ratio using stiffness as the mediation variable. The obtained results showed that the infill density affected the damping behaviour significantly. Higher infill density yielded a lower damping ratio. Nozzle size also showed a notable effect on damping. A high damping ratio was observed at a significantly low value of nozzle size. The results were confirmed using the theoretical analysis based on the underlying causes due to porosity in the MEX structure.
Open Access
The effect of printing parameters on crack growth rate of FDM ABS cantilever beam under thermo-mechanical loads
(Elsevier, 2022-01-04) He, Feiyang; Alshammari, Yousef Lafi A.; Khan, Muhammad
Fused deposition modelling (FDM) is the most widely used additive manufacturing (AM) process in the customised and low-volume production industries. Acrylonitrile butadiene styrene (ABS) is the most commonly used thermoplastic printing material for FDM. The fabricated FDM ABS parts commonly work under thermo-mechanical loads in reality. In order to produce the high fatigue performance FDM ABS components, it is significant to investigate the effect of 3D printing parameters on crack growth. Hence, this research evaluated the crack propagation under bending fatigue test for FDM ABS beam in high-temperature conditions with varying printing parameters, including building orientations, nozzle size and layer thickness. The combination of three building orientations (0°, ±45° and 90°), three nozzle sizes (0.4, 0.6 and 0.8 mm) and three layer thickness (0.05, 0.1 and 0.15 mm) were tested under 50 to 70 °C environmental temperature ranges. The research attempted to investigate the relationship between crack growth rate and different printing parameter combinations. The study also attempted to determine the possible parameter combination which achieved the longest fatigue life for the FDM ABS specimen. Preliminary experimental results showed that the specimen with 0° building orientation, 0.8 mm filament width and 0.15 mm layer thickness vibrated for the longest time before the fracture at every different temperature.
Open Access
Effects of printing parameters on the fatigue behaviour of 3D-printed ABS under dynamic thermo-mechanical loads
(MDPI, 2021-07-19) He, Feiyang; Khan, Muhammad
Fused deposition modelling (FDM) is the most widely used additive manufacturing process in customised and low-volume production industries due to its safe, fast, effective operation, freedom of customisation, and cost-effectiveness. Many different thermoplastic polymer materials are used in FDM. Acrylonitrile butadiene styrene (ABS) is one of the most commonly used plastics owing to its low cost, high strength and temperature resistance. The fabricated FDM ABS parts commonly work under thermo-mechanical loads in actual practice. For producing FDM ABS components that show high fatigue performance, the 3D printing parameters must be effectively optimized. Hence, this study evaluated the bending fatigue performance for FDM ABS beams under different thermo-mechanical loading conditions with varying printing parameters, including building orientations, nozzle size, and layer thickness. The combination of three building orientations (0°, ±45°, and 90°), three nozzle sizes (0.4, 0.6, and 0.8 mm) and three-layer thicknesses (0.05, 0.1, and 0.15 mm) were tested at different environmental temperatures ranging from 50 to 70 °C. The study attempted to find the optimal combination of the printing parameters to achieve the best fatigue behaviour of the FDM ABS specimen. The experiential results showed that the specimen with 0° building orientation, 0.8 mm filament width, and 0.15 mm layer thickness vibrated for the longest time before the fracture at each temperature. Both a larger nozzle size and thicker layer height can increase the fatigue life. It was concluded that printing defects significantly decreased the fatigue life of the 3D-printed ABS beam.
Open Access
An empirical torsional spring model for the inclined crack in a 3D-printed acrylonitrile butadiene styrene (ABS) cantilever beam
(MDPI, 2023-01-18) Yang, Zhichao; He, Feiyang; Khan, Muhammad
This paper presents an empirical torsional spring model for the inclined crack on a 3D-printed ABS cantilever beam. The work outlined deals mainly with our previous research about an improved torsional spring model (Khan-He model), which can represent the deep vertical (90°) crack in the structure. This study used an experimental approach to investigate the relationships between the crack angle and torsional spring stiffness. ABS cantilever beams with different crack depths (1, 1.3 and 1.6 mm) and angles (30, 45, 60, 75 and 90°) were manufactured by fused deposition modelling (FDM). The impact tests were performed to obtain the dynamic response of cracked beams. The equivalent spring stiffness was calculated based on the specimen’s fundamental frequency. The results suggested that an increased crack incline angle yielded higher fundamental frequency and vibration amplitude, representing higher spring stiffness. The authors then developed an empirical spring stiffness model for inclined cracks based on the test data. These results extended the Khan-He model’s application from vertical to inclined crack prediction in FDM ABS structures.
Open Access
Evolution and new horizons in modeling crack mechanics of 3D printing polymeric structures
(Elsevier, 2021-02-01) He, Feiyang; Thakur, Vijay Kumar; Khan, Muhammad A.
Three-dimensionally printed parts are widely used to fabricate polymeric structures in industrial applications. The continuous use of these components in practical applications makes them prone to fracture owing to crack propagation. Extensive research articles and reviews have been published to introduce the phenomenon and significance of crack propagation behavior of polymeric structures. However, when these are reviewed with a critical eye, it has been found that a comprehensive effort is still required to compile all these previous research studies with an emphasis on thermomechanical couple loads. During the presented critical review effort, it has been found that the existing research studies and their conclusions are limited in expressing the true crack growth phenomenon for real applications. Therefore, this review concludes that the analytical and empirical study about the crack growth behavior of polymers under the time-dependent coupled loading conditions can be a novel contribution in the academic domain.
Open Access
Experimental investigation of self-cleaning behaviour of 3D-printed textile fabrics with various printing parameters
(Elsevier, 2023-01-31) Chan, Ka Po; He, Feiyang; Atwah, Ayat Adnan; Khan, Muhammad
Self-cleaning of textile fabrics is defined as the ability that the pollutants particles can be removed from the fabric surface without any external source. The application of the technology is beneficial to the environment since it conserves water, energy and laundry costs. In the past, it is typically obtained by chemical coatings, which develop low surface energy and high roughness on the fabric surface, allowing the pollutant particles or droplets to float over the surface rather than adhesion. These chemical coating methods are effective for fabrics manufactured by traditional woven-based textile technology. However, the recent advancements in 3D printing technology have evolved the manufacturing of textile fabrics but with equal challenges in self-cleaning as previous chemical coating-based methods are not useful for printed fabrics. A recent study has successfully established a linear regression model to demonstrate the relationship between secondary 3D printing parameters and the self-cleaning properties of different polymeric fabrics. This paper is intended to analyse the impact of the primary printing parameters on the self-cleaning attributes, including infill rate (IR), flow rate (FR), printing temperature (PT), printing speed (PS), and printing acceleration (PA). The experimental results were used to construct a regression polynomial to quantify the self-cleaning behaviour of the selected thermoplastic polyurethane (TPU) fabric. The models were validated experimentally to highlight the critical values of considered primary parameters for optimal self-cleaning behaviour. The obtained results indicated that FR was the most significant parameter, and all parameters affected the fabric's wettability almost equally.
Open Access
Fundamental challenges and complexities of damage identification from dynamic response in plate structures
(MDPI , 2024-09-12) Alshammari, Yousef Lafi A.; He, Feiyang; Alrwili, Abdullah Ayed; Khan, Muhammad
For many years, structural health monitoring (SHM) has held significant importance across diverse engineering sectors. The main aim of SHM is to assess the health status and understand distinct features of structures by analyzing real-time data from physical measurements. The dynamic response (DR) is a significant tool in SHM studies. This response is used primarily to detect variations or damage by examining the vibration signals of DR. Numerous scholarly articles and reviews have discussed the phenomenon and importance of using DR to predict damages in uniform thickness (UT) plate structures. However, previous reviews have predominantly focused on the UT plates, neglecting the equally important varying thickness (VT) plate structures. Given the significance of VT plates, especially for academic researchers, it is essential to compile a comprehensive review that covers the vibration of both the UT and VT cracked plate structures and their identification methods, with a special emphasis on VT plates. VT plates are particularly significant due to their application in critical components of various applications where optimizing the weight, aerodynamics, and dimensions is crucial to meet specific design specifications. Furthermore, this review critically evaluates the damage identification methods, focusing on their accuracy and applicability in real-world applications. This review revealed that current research studies are inadequate in describing crack path identification; they have primarily focused on predicting the quantification of cracks in terms of size or possible location. Identifying the crack path is crucial to avoid catastrophic failures, especially in scenarios where the crack may propagate in critical dimensions of the plate. Therefore, it can be concluded that an accurate analytical and empirical study of crack path and damage identification in these plates would be a novel and significant contribution to the academic field.
Open Access
Implementation and demonstration of autonomous ultrasonic track inspection using cloud-based AI rail flaw analyzer
(Cranfield University, 2024-06-07) He, Feiyang; Durazo Cardenas, Isidro; Li, Jian; Ruiz Carcel, Cristobal; Ishola, Ademayowa; Starr, Andrew; Anderson, Robert; Price, Richard
This research successfully demonstrated autonomous rail inspection feasibility up to Technology Readiness Level (TRL) 7. A prototype integrating an autonomous rail vehicle and Sperry's Ultrasound Testing (UT) system was developed at Cranfield University. It was first tested at Cranfield’s Railways Innovation Test Area (RITA) at TRL 5 and tested at heritage operational railway, in Idridgehay, Derbyshire, UK achieving TRL 7. Experimental works included a 15-meter track test at RITA and nine rounds demonstration of a 250-meter track inspection at Idridgehay, showcasing inspection, localization, navigation accuracy, and defect location precision. The prototype successfully detected artificial rail defect during the demonstration and promptly communicated to command centre via email. We characterised the vehicle performance by measuring the positional error and detection rate. The positional accuracy measurements, verified through GPS and odometry, revealed an odometry-based error of 0.27-3.2 metres and an 8-metre GPS-associated error. The absence of differential GPS and a data fusion approach contributing to these errors. In addition, Weak 4G signal coverage in the fields impacted operator-vehicle communication and data uploading. Future iterations should address these limitations, exploring alternatives for enhanced accuracy and advancing defect-sizing technology.
Open Access
In-situ dynamic response measurement for damage quantification of 3D printed ABS cantilever beam under thermomechanical load
(MDPI, 2019-12-12) Baqasah, Hamzah; He, Feiyang; Zai, Behzad A.; Asif, Muhammad; Khan, Kamran Ahmed; Thakur, Vijay Kumar; Khan, Muhammad A.
Acrylonitrile butadiene styrene (ABS) offers good mechanical properties and is effective in use to make polymeric structures for industrial applications. It is one of the most common raw material used for printing structures with fused deposition modeling (FDM). However, most of its properties and behavior are known under quasi-static loading conditions. These are suitable to design ABS structures for applications that are operated under static or dead loads. Still, comprehensive research is required to determine the properties and behavior of ABS structures under dynamic loads, especially in the presence of temperature more than the ambient. The presented research was an effort mainly to provide any evidence about the structural behavior and damage resistance of ABS material if operated under dynamic load conditions coupled with relatively high-temperature values. A non-prismatic fixed-free cantilever ABS beam was used in this study. The beam specimens were manufactured with a 3D printer based on FDM. A total of 190 specimens were tested with a combination of different temperatures, initial seeded damage or crack, and crack location values. The structural dynamic response, crack propagation, crack depth quantification, and their changes due to applied temperature were investigated by using analytical, numerical, and experimental approaches. In experiments, a combination of the modal exciter and heat mats was used to apply the dynamic loads on the beam structure with different temperature values. The response measurement and crack propagation behavior were monitored with the instrumentation, including a 200× microscope, accelerometer, and a laser vibrometer. The obtained findings could be used as an in-situ damage assessment tool to predict crack depth in an ABS beam as a function of dynamic response and applied temperature.
Open Access
Influence of printing parameters on self-cleaning properties of 3D printed polymeric fabrics
(MDPI, 2022-07-31) Atwah, Ayat Adnan; Almutairi, Mohammed Dukhi; He, Feiyang; Khan, Muhammad A.
The processes for making self-cleaning textile fabrics have been extensively discussed in the literature. However, the exploration of the potential for self-cleaning by controlling the fabrication parameters of the fabric at the microscopic level has not been addressed. The current evolution in 3D printing technology provides an opportunity to control parameters during fabric manufacturing and generate self-cleaning features at the woven structural level. Fabrication of 3D printed textile fabrics using the low-cost fused filament fabrication (FFF) technique has been achieved. Printing parameters such as orientation angle, layer height, and extruder width were used to control self-cleaning microscopic features in the printed fabrics. Self-cleaning features such as surface roughness, wettability contact angle, and porosity were analyzed for different values of printing parameters. The combination of three printing parameters was adjusted to provide the best self-cleaning textile fabric surface: layer height (LH) (0.15, 0.13, 0.10 mm) and extruder width (EW) (0.5, 0.4, 0.3 mm) along with two different angular printing orientations (O) (45° and 90°). Three different thermoplastic flexible filaments printing materials were used: thermoplastic polyurethane (TPU 98A), thermoplastic elastomers (TPE felaflex), and thermoplastic co-polyester (TPC flex45). Self-cleaning properties were quantified using a pre-set defined criterion. The optimization of printing parameters was modeled to achieve the best self-cleaning features for the printed specimens.
Open Access
Interdependencies between dynamic response and crack growth in a 3D-printed acrylonitrile butadiene styrene (ABS) cantilever beam under thermo-mechanical loads
(MDPI, 2022-02-28) He, Feiyang; Khan, Muhammad; Aldosari, Salem Mohammed
Acrylonitrile butadiene styrene (ABS) is the most commonly used thermoplastic printing material for fused deposition modelling (FDM). FDM ABS can be used in a variety of complex working environments. Notably, the thermo-mechanical coupled loads under complex operating conditions may lead to cracking and ultimately catastrophic structural failure. Therefore, it is crucial to determine the crack depth and location before a structural fracture occurs. As these parameters affect the dynamic response of the structure, in this study, the fundamental frequency and displacement amplitude response of a cracked 3D-printed ABS cantilever beam in a thermal environment were analytically and experimentally investigated. The existing analytical model, specifically the torsional spring model used to calculate the fundamental frequency change to determine the crack depth and location was enhanced by the proposed Khan-He model. The analytical relationship between the displacement amplitude and crack was established in Khan-He model and validated for the first time for FDM ABS. The results show that a reduced crack depth and location farther from the fixed end correspond to a higher fundamental frequency and displacement amplitude. An elevated ambient temperature decreases the global elastic modulus of the cracked beam and results in a lower fundamental frequency. Moreover, a non-monotonic relationship exists between the displacement amplitude and ambient temperature. The displacement amplitude is more sensitive to the crack change than the fundamental frequency in the initial stages of crack growth.
Open Access
Leakage quantification in metallic pipes under different corrosion exposure times
(MDPI, 2024-07-20) Agala, Alaa; Khan, Muhammad A.; He, Feiyang; Alnuman, Abdulaaziz
The combined effects of aqueous corrosion, stress factors, and seeded cracks on leakage in cast iron pipes have not been thoroughly examined due to the complexity and difficulty in predicting their interactions. This study seeks to address this gap by investigating the interdependencies between corrosion, stress, and cracks in cast iron pipes to optimise the material selection and design in corrosive environments. Leakage experiments were conducted under simulated localised corrosive conditions and internal pressure, revealing that leakage increased from 0 to 25 mL with crack sizes of 0.5 mm, 0.8 mm, 1 mm, and 1.2 mm, along with corrosion times of 0, 120, 160, and 200 h, and varying stress levels. An empirical model was developed using a curve-fitting approach to map the relationships among corrosion time, crack propagation, and leakage amount. The results demonstrate that the interaction between corrosion, stress, and crack propagation was complex and nonlinear, and the leakage amount increased from 0.7 to 0.10 mm every 15 min, as evidenced by SEM microstructure images and empirical data.
Open Access
A machine learning approach to model interdependencies between dynamic response and crack propagation
(MDPI, 2020-11-30) Fleet, Thomas; Kamei, Khangamlung; He, Feiyang; Khan, Muhammad A.; Khan, Kamran Ahmed; Starr, Andrew
Accurate damage detection in engineering structures is a critical part of structural health monitoring. A variety of non-destructive inspection methods has been employed to detect the presence and severity of the damage. In this research, machine learning (ML) algorithms are used to assess the dynamic response of the system. It can predict the damage severity, damage location, and fundamental behaviour of the system. Fatigue damage data of aluminium and ABS under coupled mechanical loads at different temperatures are used to train the model. The model shows that natural frequency and temperature appear to be the most important predictive features for aluminium. It appears to be dominated by natural frequency and tip amplitude for ABS. The results also show that the position of the crack along the specimen appears to be of little importance for either material, allowing simultaneous prediction of location and damage severity
Open Access
Modal response of hybrid raster orientation on material extrusion printed acrylonitrile butadiene styrene and polyethylene terephthalate glycol under thermo-mechanical loads
(Elsevier, 2023-02-05) Almutairi, Mohammed Dukhi; Mascarenhas, Taheer A.; Alnahdi, Sultan Saleh; He, Feiyang; Khan, Muhammad A.
In this paper we look at Acrylonitrile Butadiene Styrene (ABS) and Polyethylene Terephthalate Glycol (PETG), chosen for their low cost, high strength and temperature resistance. This study evaluates the bending fatigue performance of Material extrusion (MEX) ABS and PETG cantilever beams and compares their properties while varying a printing parameter under thermal loads. The study, using custom building orientation angles of 90o, 45o and 60o between the layers, tested the beams at different temperatures from 30o to 50 °C. The results show the effects of the building orientations and the effects of temperature on the sample. The printing orientation, which is the same as loading, also slows the crack growth.
Open Access
Modelling and investigation of crack growth for 3D-printed acrylonitrile butadiene styrene (ABS) with various printing parameters and ambient temperatures
(MDPI, 2021-10-29) Alshammari, Yousef Lafi A.; He, Feiyang; Khan, Muhammad A.
Three-dimensional (3D) printing is one of the significant industrial manufacturing methods in the modern era. Many materials are used for 3D printing; however, as the most used material in fused deposition modelling (FDM) technology, acrylonitrile butadiene styrene (ABS) offers good mechanical properties. It is perfect for making structures for industrial applications in complex environments. Three-dimensional printing parameters, including building orientation, layers thickness, and nozzle size, critically affect the crack growth in FDM structures under complex loads. Therefore, this paper used the dynamic bending vibration test to investigate their influence on fatigue crack growth (FCG) rate under dynamic loads and the Paris power law constant C and m. The paper proposed an analytical solution to determine the stress intensity factor (SIF) at the crack tip based on the measurement of structural dynamic response. The experimental results show that the lower ambient temperature, as well as increased nozzle size and layer thickness, provide a lower FCG rate. The printing orientation, which is the same as loading, also slows the crack growth. The linear regression between these parameters and Paris Law’s coefficient also proves the same conclusion.
Open Access
A practical demonstration of autonomous ultrasonic testing for rail flaws inspection
(Cranfield University, 2022-11-08) He, Feiyang; Durazo-Cardenas, Isidro; Liu, Haochen; Rahman, Miftahur; Rahimi, Masoumeh; Starr, Andrew; Poulter, Michael
This study established the viability of autonomous ultrasonic inspections at the technology readiness level 5 (TRL 5). An autonomous ultrasonic rail inspection prototype was developed using commercially available ultrasonic instruments and an unmanned on-track vehicle platform consisting of a Clearpath's Warthog and a road-rail vehicle (RRV) trolley. The prototype was designed to travel back and forth on a segment of the test track during the test programme. Repeated fault checks were able to discover seeded artificial flaws at depths of 23 and 27 mm. The detection was indicated by an audio alarm triggered when the ultrasonic emissions exceeded the threshold of the detector gate. A plain text message sent over local area network (LAN) WIFI to a virtual server was also used to demonstrate the transmission of detection messages. The repeatability of the inspection prototype's positioning relative to the problem was confirmed using odometry, global navigation satellite system (GNSS), and positional measurements. The results of the three measurement methods were in good agreement, and the positioning inaccuracy varied between 3 and 7 cm. This study demonstrated the potential of autonomous ultrasonic checks and gave recommendations for further work and limitations.
Open Access
Role of dynamic response in inclined transverse crack inspection for 3D-printed polymeric beam with metal stiffener
(MDPI, 2023-04-14) Francese, Arturo; Khan, Muhammad; He, Feiyang
This paper aims to quantify the relationship between the dynamic response of 3D-printed polymeric beams with metal stiffeners and the severity of inclined transverse cracks under mechanical loading. Very few studies in the literature have focused on defects starting from bolt holes in light-weighted panels and considered the defect’s orientation in an analysis. The research outcomes can be applied to vibration-based structure health monitoring (SHM). In this study, an acrylonitrile butadiene styrene (ABS) beam was manufactured through material extrusion and bolted to an aluminium 2014-T615 stiffener as the specimen. It simulated a typical aircraft stiffened panel geometry. The specimen had seeded and propagated inclined transverse cracks of different depths (1/1.4 mm) and orientations (0°/30°/45°). Then, their dynamic response was investigated numerically and experimentally. The fundamental frequencies were measured with an experimental modal analysis. The numerical simulation provided the modal strain energy damage index (MSE-DI) to quantify and localise the defects. Experimental results showed that the 45° cracked specimen presented the lowest fundamental frequency with a decreased magnitude drop rate during crack propagation. However, the 0° cracked specimen generated a more significant frequency drop rate with an increased crack depth ratio. On the other hand, several peaks were presented at various locations where no defect was present in the MSE-DI plots. This suggests that the MSE-DI approach for assessing damage is unsuitable for detecting cracks beneath stiffening elements due to the restriction of the unique mode shape at the crack’s location.
Open Access
Tribological characterisation and modelling for the fused deposition modelling of polymeric structures under lubrication conditions
(MDPI, 2023-10-17) He, Feiyang; Xu, Chenyan; Khan, Muhammad
In recent years, additive manufacturing technology, particularly in plastic component fabrication, has gained prominence. However, fundamental modelling of the influence of materials like ABS, PC, and PLA on tribological properties in fused deposition modeling (FDM) remains scarce, particularly in non-lubricated, oil-lubricated, and grease-lubricated modes. This experimental study systematically investigates the effects of material type, lubrication method, layer thickness, and infill density on FDM component tribology. A tribology analysis is conducted using a TRB3 tribometer. The results indicate a coefficient of friction (CoF) range between 0.04 and 0.2, generally increasing and decreasing with layer thickness and filler density. The lubrication impact hinges on the material surface texture. The study models the intricate relationships between these variables via full-factor analysis, showing a strong alignment between the modelled and measured friction coefficients (an average error of 3.83%). Validation tests on different materials affirm the model’s reliability and applicability.