Figure 3 - available via license: Creative Commons Attribution 4.0 International
Content may be subject to copyright.
Source publication
One of the problems with composites is their weak impact damage resistance and post-impact mechanical properties. Composites are prone to delamination damage when impacted by low-speed projectiles because of the weak through-thickness strength. To combat the problem of delamination damage, composite parts are often over-designed with extra layers....
Context in source publication
Context 1
... results can be obtained from the low-velocity impact test. Typical time versus impact energy and peak loads plots are illustrated in Figure 3 [36]. For the impact energy-time history curve, the highest peak of the curve shows the maximum impact energy, and the end of the curve shows the absorbed energy. ...
Citations
... A method proposed by Martinez et al. was used to analyze the spread-flow kinetic effect of fluid drops on the unidirectional fiber beds [15]. Additionally, computational studies have been performed to assist in better understanding the impact of different parameters [16,17]. ...
Carbon fibers (CFs) have received tremendous attention since their discovery in the 1860s due to their unique properties, including outstanding mechanical properties, low density, excellent chemical resistance, good thermal conductivity, etc [...]
... Damage types, such as delamination and cracks in composite materials, not only compromise the stability and strength of the structure over time but also diminish safety performance during application. In these structures, complex damage mechanisms occur that are not observed in metal materials, including fiber breakage, separation from the interface, or delamination [7,8]. Some damages carry a significant risk owing to critical strength loss in the part of the material that is not visible from the outside, called Barely Visible Impact Damage (BVID) [9][10][11][12][13]. ...
In recent years, there has been a widespread utilization of composite materials, particularly in critical sectors such as aircraft manufacturing, where errors can have significant consequences. This has generated a need for effective protection of composite materials both during and after production. Detecting internal damage in composite materials, which is often visually imperceptible, becomes crucial and can be assessed using non-destructive testing methods. In this study, glass and carbon woven fabric-reinforced epoxy composites intentionally embedded with artificial damages during manufacturing were subjected to impact tests. The composite materials were scanned using the ultrasonic method to detect damages before and after the impacts. Particularly in glass fiber-reinforced composites (GFRP), the damaged area in the artificially damaged glass lamella sample (G/AL) was calculated to be 4–5 times higher than in the undamaged sample (G/UD). Damaged area values in GFRP were calculated as 72.88 mm² in the G/UD sample, 143.74 mm² in the G/AC sample, and 315.93 mm² in the G/AL sample. While the samples with artificial damage in carbon fiber-reinforced composites (C/AL, C/AC) were perforated during the impact tests, the undamaged samples (C/UD) were not. The images obtained were evaluated using image processing algorithms and were employed in damage analysis. In conclusion, the applied method and the developed image processing algorithm yielded successful results in analyzing barely visible damages and detecting damaged areas.
... Although this has many advantages, composite materials have disadvantages compared to metal-based materials. Composite materials have the disadvantage of being more sensitive to impact load damage than metal materials due to different damage modes [4]. Damage to impact loads can be classified into low, medium, or high velocity, depending on the parameters. ...
... (4) Once the simulation shows that the material has reached the failure criteria where the index value has reached 1, the material properties will experience linear degradation. After that, the material will experience damage evolution to calculate the extent of the degradation of material properties. ...
... Its applications were found in various fields, such as construction, aerospace, military, automotive, etc. [1][2][3][4][5][6]. To meet the high demand for composite laminate development, various studies on the customization of composite laminate have been done in the past decades, from studies of material physical properties [7][8][9], laminate construction guidelines [10,11], to variations of blending techniques [12], such as guideline-based [13], Stacking Sequence Table (SST) [14], Ply Drop Sequence (PDS) [15], and many more [16][17][18][19][20]. ...
... In Figure 22, 14-layer pure glass composite with curved surface and studies in the literature [45][46][47][48][49] are presented comparatively. When the graph was examined, it was seen that the current study was compatible with the studies in the literature. ...
The aim of this study is to produce curved sandwich composites with different arrays by adding Ethylene Propylene Diene Monomer (EPDM) rubber interlayers between glass fiber woven fabrics and to investigate their behaviours under low-velocity impact. For this purpose, sandwich plates were produced through the vacuum infusion method by using glass fiber and rubber layers on the steel mold manufactured in curved form. Impact tests were applied on the plates and the effect of the stacking sequence for glass fibers/rubber layer on the impact energy absorption was examined. The energy absorption property of the composites was improved by a maximum of 45% with a layer epdm used in the midplane of the composite. Also, when rubber layers were used on the outermost surface of the composites, the damage area reduced by 14%. In the numerical part, the tests were modelled using LS-DYNA finite element packaged programme and the Hashin failure criterion-based material model was used in order to view any damages on the composite structure after the tests. The agreement between numerical and experimental results was obtained with a maximum error of 19%
... Drop weight impact tests are a type of low velocity impact tests and based on the principle that a mass hits the specimen as a result of vertical free fall from a certain height. [10,11]. The damage resistance, impact behavior, threshold values for penetration and perforation, impact resistance, absorbed energy, contact forces and damage areas of composite materials are determined with the drop weight impact tests [9,[11][12][13][14]. ...
As it is known, impact damage is a major mechanical phenomena for composite materials especially used in the aerospace structures. The factors affecting the impact behaviour of the composites depend on the impactor systems as well as the target material. In this study ply number and impactor geometry effects of carbon fiber reinforced epoxy composites were investigated by impact tests. In this context, drop weight impact tests were carried out at 6J, 12J and 24J energy levels by using hemispherical impactors with 10 mm and 20 mm diameters. Laminated composites were manufactured in 6, 10 and 14 plies with vacuum infusion method. The effects of laminate thickness, impactor diameter and impact energy effects on the force, velocity, absorbed energy and damage surfaces were investigated. It is observed that impactor geometries and velocities caused the different damage mechanisms in composites and impactors played an important role in determining the penetration and perforation behaviours of composites.
... The experiments were simulated using FE in order to find optimum test parameters such as heating power and time step. Alomari et al. [6] also used FE simulations to predict the damage in fiber reinforced polymer plates. Experimental results from low-velocity impact tests were used to calibrate the model, which was then used to model various scenarios. ...
This work presents a hybrid thermography, computational, and Artificial Neural Networks (ANN) approach to characterize beneath the surface defects in composites. Computational simulations are created to model thermography experiments carried out on composite plates with controlled damage in the form of drilled holes. The computational models are then extended to create hypothetical composite component geometries of plates and pipes with embedded defects of varying sizes and shapes. The data from the computational simulations are fed to artificial neural networks to train them to predict and characterize defect sizes and shapes. The predictions from the neural networks are compared to the actual dimensions from the computational models. These predictions show a high level of accuracy especially when quantifying thermal image information and using it to train the neural network. This accuracy is around 10% and 19% for predicting defect depth in plates and pipes, respectively. This hybrid approach has the advantage of not relying on experimental data (experiments were used only for validation) and predicting damage shape and size. This suggests that the methodology used in this study combining lock-in thermography experiments, computational simulations, and ANNs is a viable method for a potential nondestructive testing (NDT) method for detecting embedded defects within composite pipes in real applications. What makes this approach attractive is that it can be used with live thermal images that can be fed directly into the ANN model.
... In addition to that, the contact model ONE_WAY_SURFACE_TO_SURFACE_TIEBREAK was used to bind the fabric plies together. Similarly, the composite orientations and stacking sequences were defined using ACP [23]. Figure 2 shows the arrangement of the meshed projectile and laminate. ...
This study investigates the applicability of carbon and glass-based hybrid fabric reinforced polymer composites for ballistic applications due to their high specific strength, corrosion and impact resistance properties. The high velocity impact response of glass and carbon fiber-epoxy composites have been numerically investigated using ANSYS LS-Dyna simulation tool. The effect of reinforcement-fiber orientation on the impact response of composites was studied. Furthermore, hybrid and non-hybrid fiber reinforced polymer composites consisting of forementioned reinforcement fabrics were modelled to study the effect of fabric hybridization on the impact behavior of such composites. The results indicated that the cross-ply orientation (0/90) offers better resistance against impacts by hemispherical ended projectile of 9 mm diameter compared to other orientations and thus absorb more impact energy. The stacking of carbon fabric sandwiched between glass fabric layers was the optimum hybrid sequence to resist high velocity impacts at 373 m s⁻¹ and absorb higher impact energy compared to other stacking sequences considered in this study. These hybrid composites are thus found to be ideal for sacrificial structural components to protect other sensitive installations as they are found to withstand impacts at velocities up to 127 m s⁻¹ and are also cost-effective.
... A conclusion was made that impacting under low velocity did cause deformation to the structures and led to fractures of the fibres and thus a reduction of load carrying abilities (Korkees, Arnold and Alston, 2018). A research study carried out by (AlOmari et al., 2020) showed that the amount of energy absorbed related to the thickness of a single layer, number of layers, and stacking sequence. It was concluded that the stacking sequence of [90/0/45/-45]s was better than [60/45/-45/-60]s showing great importance and reliance on stacking sequence (AlOmari et al., 2020). ...
... A research study carried out by (AlOmari et al., 2020) showed that the amount of energy absorbed related to the thickness of a single layer, number of layers, and stacking sequence. It was concluded that the stacking sequence of [90/0/45/-45]s was better than [60/45/-45/-60]s showing great importance and reliance on stacking sequence (AlOmari et al., 2020). Further research was conducted by (Korkees et al. 2020) (Korkees, Allenby and Dorrington, 2020) on 3D printed carbon fibre/nylon composites and found that by increasing the fibre volume fraction, the flexural strength and the stiffness of 3D printed composites increased. ...
Purpose
Composites 3D printing has the potential to replace the conventional manufacturing processes for engineering applications because it allows for the manufacturing of complex shapes with the possibility of reducing the manufacturing cost. This paper aims to analyse the performance of 3D printed fibre reinforced polymer composites to investigate the energy absorption capabilities and the residual properties before and after impact.
Design/methodology/approach
Various composites composed of carbon fibres and Kevlar fibres embedded into both Onyx and nylon matrix were printed using Markforged-Two 3D printers. Specimens with different fibre orientations and fibre volume fractions (Vf) were printed. A drop-weight impact test was performed at energies of 2, 5, 8 and 10 J. Flexural testing was performed to evaluate the flexural strength, flexural modulus and absorbed energy under bending (AEUB) before and after impact. Additionally, 3D printed carbon fibre composites were tested at two different temperatures to study their behaviour under room and sub-ambient temperatures. Failure modes were investigated using optical and high depth of field microscopes for all 3D printed composite samples.
Findings
Kevlar/nylon composites with a unidirectional lay-up and 50% Vf exhibited the most prominent results for AEUB at room temperature. The high-Vf carbon fibre composite showed the highest ultimate strength and modulus and performed best at both temperature regimes.
Originality/value
The work, findings and testing produced in this paper are entirely original with the objective to provide further understanding of 3D printed composites and its potential for use in many applications.
... The energy after reaching the maximum value dropped until it became constant, indicating the value of permanent absorbed energy [29]. The end of the curve depicts the plastic energy dissipated in the form of permanent deformation/ damage/delamination such as matrix cracking, fiber fracture, and kinking [30]. Hence the damage evolution is the total of plastic energy [30], found highest in laminate (L5) and (L4), lowest in laminate (L7) at both the velocities respectively, depicted in Energytime curves( figures 5(c), (d).The part of the elastic energy was given back to the impactor as the rebound energy [27] .The maximum energy at maximum force is the sum of elastic energy(absorbed energy) and plastic energy (dissipated energy) depicted in figures 6(a), (b). ...
... The end of the curve depicts the plastic energy dissipated in the form of permanent deformation/ damage/delamination such as matrix cracking, fiber fracture, and kinking [30]. Hence the damage evolution is the total of plastic energy [30], found highest in laminate (L5) and (L4), lowest in laminate (L7) at both the velocities respectively, depicted in Energytime curves( figures 5(c), (d).The part of the elastic energy was given back to the impactor as the rebound energy [27] .The maximum energy at maximum force is the sum of elastic energy(absorbed energy) and plastic energy (dissipated energy) depicted in figures 6(a), (b). It was observed that the elastic energy was the highest for laminate L7 [B/C/B/C](4.8 ...
The main aim of this work is to study thedamage tolerance of hybrid basalt and carbon fiber-reinforced composite subjected to low velocity impact (LVI) at different velocities, 2.89 m s ⁻¹ and 4.42 m s ⁻¹ , simulated using a CEAST drop hammer testing machine and Dynamic Mechanical Analysis(DMA) were conducted to characterize the sample. In this article, the detailed failure mechanism of seven composite laminates (Basalt fiber/Bismaleimide(BMI)-diallyl Bisphenol A(DABA), Carbon fiber/BMI-DABA, Carbon and basalt fiber(hybrid fibers)/BMI-DABA) were studied under loading of LVI. Through the experiment, it was also substantiated that the hybrid fiber-reinforced composites possessed better damage tolerance and thermo mechanical properties than the homogenous fiber-reinforced composites. The hybrid fiber composites that were produced vary in the number of carbon fiber to basalt fiber ratio and stacking sequence. The impacted surface was analyzed at macro level by using Image J software. The impact force, the energy absorbed, and the deformation of the laminates under impact load were scrutinized extensively, and it was inferred that the basalt fiber intercalated with carbon fiber with BMI/DABA possessed the highest damage resistance than the other composite laminates under study. The highest peak force 5702 N and 9241 N with the highest elastic energy 4.8 J, 11.7 J and with lower deformation (3.85 mm, 6.09 mm) and deformation area (22.79 mm ² , 28.09 mm ² ) was observed in the intercalated hybrid laminate.
