Milad SaeedifarDelft University of Technology | TU · Faculty of Aerospace Engineering (AE)
Milad Saeedifar
Ph.D.
About
45
Publications
24,342
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
1,911
Citations
Publications
Publications (45)
Nylon 6,6 electrospun nanofibers have demonstrated a notable ability to enhance the interlaminar fracture toughness of fiber-reinforced polymer composites. This study aims to further improve the toughening properties of Nylon 6,6 nanofibers through a dielectric-barrier discharge (DBD) plasma treatment. Initially, nanofibers were produced by electro...
This study investigates the effect of the interleaving nanofibers, made of NBR/PCL blend, on the interlaminar fracture toughness of carbon/epoxy laminates. Different nanomat thicknesses, ranging from 20 μm to 120 μm, were tested at Mode-I and mode-II and results were compared to the non-modified laminates. Acoustic Emission (AE) technique was used...
This study aims to quantify impact damage in laminated composites using acoustic emission (AE) and to verify the AE results with finite element (FE) method. Carbon fiber reinforced polymer (CFRP) composite specimens were subjected to quasi‐static out‐of‐plane indentation loading. A procedure, including feature extraction, feature selection, data di...
This article investigates the effect of alternating the sequence of variable-energy repeated low-velocity impact on the residual strength of carbon fiber reinforced polymer (CFRP) laminates. Quasi-isotropic CFRP specimens were impacted using three impact energy levels, that is, Low (L), Medium (M), and High (H). Every group, out of three groups in...
This paper studies the effect of interlaminar and intralaminar damage mechanisms on the quasi-static indentation strength of composite laminates. To this aim, two carbon/epoxy laminates with a unidirectional lay-up of [024] (is named SU) and a cross-ply lay-up of [011/90]S (is named SC) were fabricated and subjected to quasi-static out-of-plane ind...
The present study proposes a comprehensive integrity assessment approach for a full-scale adhesively-bonded bi-material joint for maritime applications. The joint represents a cross-section of the bond-line connection of a ship with a steel hull and a sandwich composite superstructure. The full-scale joint consists of a sandwich composite core adhe...
Thicker bondlines along with manufacturing-tolerant and fracture-resistant adhesives are trends visible across different industries, especially maritime. In this work, two contrasting adhesives: an elastic-brittle epoxy-based, and a nonlinear-ductile methyl methacrylate (MMA) are characterized and compared via tensile, compact tension (CT) and doub...
The aim of this research was to investigate the self-healing potential of damaged Al joints when bonded using novel eco-epoxide adhesives derived from tannic acid (TA). Two eco-epoxy components based on TA, (A) glycidyl ether and (B) glycidyl phosphate ester of TA, were produced. The effect of the eco-epoxy components on the self-healing ability wa...
The aim of this paper is to study the self-healing capability of fractured Al joints bonded with novel eco-epoxide adhesives synthesized from a bio-renewable raw material (tannic acid – TA). Two synthesized eco-epoxy components based on TA, (A) glycidyl ether and (B) glycidyl phosphate ester of TA, were used as a replacement for the toxic epoxy com...
The present study evaluates the toughening capability of electrospun PA66 nanofibers for carbon/epoxy composite laminates subjected to mode II loading conditions at elevated temperatures. The Dynamic Mechanical Analysis (DMA) test showed that the glass transition temperature of the produced nanofibers is in a range of ∼60–80 °C. Accordingly, End-No...
![FRP components of the UK's FRP bridges [56][61-63]](profile/Mohammad-Fotouhi/publication/349086105/figure/tbl2/AS:1011795472965636@1618242247853/FRP-components-of-the-UKs-FRP-bridges-5661-63_Q320.jpg)
This paper presents a concise state-of-the-art review on the use of Fiber Reinforced Polymers (FRPs) in bridge engineering. The paper is organized into commonly used FRP bridge components, and different materials/manufacturing techniques used for repairing and construction of FRP bridges. Efforts have been made to give a clear and concise view of F...
This study is devoted to the use of acoustic emission technique for a comprehensive damage assessment, that is, damage detection, localization, and classification, of an aeronautical metal-to-composite bonded panel. The structure comprised a titanium panel adhesively bonded to carbon fiber-reinforced plastic omega stringers. The panel contained a s...
Interleaving composite laminates with nanofibrous mat is one of the most reliable methods for increasing interlaminar fracture toughness. The present study seeks to find out how the damage mechanisms of carbon fiber reinforced polymers (CFRPs), subjected to the mode-I and mode-II fracture tests, are affected while those are modified by interleaved...
This paper presents a concise state-of-the-art review on the use of Fiber Reinforced Polymers (FRPs) in bridge engineering. The paper is organized into commonly used FRP bridge components, and different materials/manufacturing techniques used for repairing and construction of FRP bridges. Efforts have been made to give a clear and concise view of F...
The present study is focused on the characterization of the fatigue damage features in carbon/epoxy laminates under mode-II loading conditions. To this aim, a sinusoidal cyclic load was applied to the End-Notched Flexural (ENF) specimens and the fatigue behavior of specimens was investigated. Scanning Electron Microscope (SEM) was used to identify...
The increasing interest for the application of adhesive joints in naval superstructures motivates researchers to gain an in-depth understanding of the mechanical behaviour and failure mechanisms of these joints. This work reports on an experimental study of the deformation behaviour and damage evolution of a full-scale multi-material joint using di...
This paper investigates the loading rate effect on both mechanical properties and damage accumulation process of [0°2/90°4]S carbon fibre-polymer laminates under tensile loading. In-situ edge observations, Acoustic Emission and Digital Image Correlation techniques were utilized simultaneously to monitor the state of damage in real time. Results sho...
The aim of this work was to investigate the effect of loading angle variation on the pseudo-ductility of quasi-isotropic (QI) hybrid composite laminates. Previously, hybrids of thin-ply carbon fibres and standard glass fibres were found to have an excellent pseudo-ductile behaviour both in unidirectional (UD) and QI configurations when subjected to...
![Fig. 3. A typical AE waveform and the most important features [36].](profile/Dimitrios-Zarouchas/publication/340917437/figure/fig4/AS:887767299010563@1588671626687/A-typical-AE-waveform-and-the-most-important-features-36_Q320.jpg)
Damage characterization of laminated composites has been thoroughly studied the last decades where researchers developed several damage models, and in combination with experimental evidence, contributed to better understanding of the structural behavior of these structures. Experimental techniques played an essential role on this progress and among...
This study is devoted to the damage characterization of Non-Crimp Fabric (NCF), 2D plain-woven (2D-PW) and 3D orthogonal plain-woven (ORT-PW) carbon/epoxy laminates, subjected to compression after multiple-impact loading, using Acoustic Emission (AE). The ultrasonic C-scan images showed that the interlaminar damage area induced by the single and 3-...
Mechanics of double-lap Steel-to-CFRP adhesively-bonded joints loaded in tension are investigated experimentally using Digital Image Correlation (DIC) and Acoustic Emission (AE), analytically using a one-dimensional closed-form solution and numerically with Finite Element analysis. The double-lap bi-material joints are fabricated of a steel core ad...
The aim of the present study is to characterize the damage in bi-material steel-to-composite double-lap adhesively-bonded joints using Acoustic Emission (AE). Two different structural adhesives, a ductile (Methacrylate-based) and brittle (Epoxy-based), were used to bond CFRP skins to a steel core. The fabricated joints were loaded in tension while...
This paper investigates the effect of the fabric architecture and the z-binding yarns on the compression after multiple impacts behavior of composites. Four fiber architectures are investigated: non-crimp fabric (NCF), 2D plain weave (2D-PW), 3D orthogonal plain (ORT-PW) and twill (ORT-TW) weave. The specimens were subjected to single and multiple...
This study aims to use the passive and active acoustic-based health monitoring methods for impact damage
assessment of composite structures. To this aim, a Carbon Fiber Reinforced Polymer (CFRP) composite plate was
fabricated and subjected to a simulated low-velocity impact by performing repeated quasi-static indentation tests
where a loading-unloa...
This paper investigates the effect of temperature and hybridization on the impact damage evolution and post-impact residual strength of hemp/epoxy, basalt/epoxy and their hybrid laminates, using mechanical and acoustic emission (AE) based analysis. To start with, the specimens were impacted by a drop weight impact tower machine at two temperatures...
Despite the key advantages of Fiber Reinforced Polymer (FRP) composites, they are susceptible to Barely Visible Impact Damage (BVID) under transverse loadings. This study investigates BVID in two quasi-isotropic carbon/epoxy laminates under quasi-static indentation and Low-Velocity Impact (LVI) loadings using Acoustic Emission (AE). First, the evol...
This study focuses on the clustering of the indentation-induced interlaminar and intralaminar damages in carbon/epoxy laminated composites using Acoustic Emission (AE) technique. Two quasi-isotropic specimens with layups of [60/0/-60]4S (is named dispersed specimen) and [604/04/-604]S (is named blocked specimen) were fabricated and subjected to a q...
This study introduces a comprehensive set of designed and tested glass/epoxy composites, AE monitoring and
signal processing techniques; (i) to investigate the effect of multiple delaminations on buckling and postbuckling behaviors of laminated composites and (ii) to evaluate Acoustic Emission (AE) technique ability to
monitor the buckling delamina...
The aim of this study is to investigate the failure of cracked aluminum plates repaired by one-side composite patches under fatigue loading using Acoustic Emission (AE) and fractography images. Rectangular specimens made of 6061 aluminum alloy with central through thickness pre-cracks were repaired using glass/epoxy laminated patches. The specimens...
The aim of this study was to investigate the applicability of acoustic emission (AE) technique to evaluate delamination crack in glass/epoxy composite laminates under quasi-static and fatigue loading. To this aim, double cantilever beam specimens were subjected to mode I quasi-static and fatigue loading conditions and the generated AE signals were...
Fiber reinforced plastic composites are being increasingly used in engineering applications due to their high specific stiffness and strength. On the other hand, the incidence of internal defects may considerably alter the stiffness and reduce the strength and lifetime of the composites. The principal mode of failure in laminated composite material...
The Structural integrity of composite structures depends on the use of appropriate damage detection and structural health monitoring methods in design and operation stages. In this paper, the initiation and propagation of delamination in laminated composite materials are investigated by performing Double Cantilever Beams (DCBs) tests. Acoustic Emis...
This paper focuses on quantification of damage mechanisms in Standard Open-Hole Tensile (OHT) laminated composites using Acoustic Emission (AE) and Finite Element Method (FEM). To this aim, OHT tests were carried out in unidirectional glass/epoxy composite materials. AE accompanied with a wavelet and fuzzy C-means clustering methods were used to di...
Push-out delamination is a serious concern in the drilling of fibre-reinforced composite materials. This damage occurs as the drill reaches the exit side of the material and can reduce the strength and stiffness of the structure. In this paper, a three-point bending test is performed on glass/epoxy-laminated composites to simulate the push-out dela...
Acoustic Emission (AE) is a capable approach to characterize delamination initiation and propagation in laminated composite materials. One of the major issues of applying this methodology is to establish a reasonable correlation between delamination initiation and propagation and resultant AE features. To this aim, initiation and propagation of mod...
Delamination is one of the most common modes of failure in laminated composites and it leads to the loss of structural strength and stiffness. In this paper, mode I, mode II, and mixed of these pure modes were investigated using mechanical data, Finite Element Method (FEM) and Acoustic Emission (AE) signals. Experimental data were obtained from in...
The main objective of this study is to determine the crack tip position during propagation of mode I delamination and also to evaluate interlaminar fracture toughness (GIC) in glass/epoxy composite specimens. The crack tip location was identified using two methods: a) localization of the AE signal source and b) the cumulative AE energy. Interlamina...
In this paper acoustic emission (AE) technique was used to evaluate the inter-laminar fracture energy for the initiation of delamination, Gc, in mode I, mode II and the combination of these pure modes for glass/epoxy composites. The AE signals are transient waves originated from the damage mechanisms such as matrix cracking, fiber failure, etc. dur...
Delamination is the most common failure mode in laminated composites and it leads to loss of structural strength and stiffness. In this paper, acoustic emission monitoring was applied on the carbon/epoxy laminated composites when subjected to mode I, mode II, and mixed-mode I and II loading conditions. The main objective is to investigate delaminat...
In this article, acoustic emission monitoring was used to identify different types of damage mechanisms which occur during delamination of sandwich structures. Features of the obtained acoustic emission signals and wavelet-based signal processing technique were utilized to discriminate failure mechanisms during the delamination test. Dominant damag...
Questions
Questions (2)
Hello Everyone,
I did several DSC tests on the electrospun PA66 nanofibers to obtain the glass transition temperature. According to the material datasheet, the Tg point of PA66, as cast, is around 55 C, but I thought it might be different for the nanofibers compared to the bulk material. I got different results from the DSC tests. You can find some of the results attached.
- The first case: The sample was subjected to a heating-cooling-heating (HCH) cycle from 0 C to 180 C by a heating/cooling ramp of 10 C/min.
- The second case: The sample has experienced a HCH cycle from 0 to 300 C.
- The third case: It is similar to the second case, but I think the sample contained moisture.
What is the Tg of the nanofibers? Because in the first heating cycle, two break points, one before 50 C and one before 100 C, are visible and for the reheating cycle, there is no break point in this temperature range? What is the small drop observed around 150 C?
I would be grateful if you could help me with the interpretation of the results.
Thanks in advance!
Hello everybody,
I'm modeling the buckling of a laminated composite consisting a pre-delamination in ABAQUS. To this aim, I ran a buckle step and extracted displacements results.Then, I ran a STATIC-GENERAL step and used the imperfection keyword to import the displacement results of BUCKLE step to STATIC-GENERAL step. But, I have a problem: As the ABAQUS documentation said, any contact can not be defined in BUCKLE step. Thus, the predicted buckling mode shapes by BUCKLE step are wrong (The following pictures).Consequently, the results of post-buckling step are wrong too.
How can I fix this problem?How can I define the contact in BUCKLE step?
Regards
Milad
