The nanofabrication of long-range ordered metal nanostructures has garnered significant research attention in the advancement of plasmonic-assisted sensor development. In this study, we report efficient nanofabrication of silver arrays on Teflon (Tef/Ag) for fabricating a surface-enhanced Raman spectroscopy (SERS) sensor for detecting multiple pollutants. The number of laser pulses was systematically varied from 200 to 10000 to study its impact on the morphological features of Ag nanoarrays. Atomic Force Microscopy (AFM) and UV-visible spectroscopy were employed to study the morphological and optical characteristics, respectively. The physical properties were then correlated to their corresponding sensing activities. The number of laser pulses was optimized to achieve the highest SERS sensing efficiency. The sensor fabricated at 5000 laser pulses exhibited the highest SERS enhancement, attributed to the formation of a highly dense metal nano-island formation (Fig. 1a). Compared to silicon and quartz, Teflon provided the best substrate for achieving the highest SERS enhancement. An enhancement factor of 3.1 × 10 7 has been estimated for Teflon/Ag sensor, which showed superior efficiency of the fabricated sensor. The reproducibility of the sensor showed relative standard deviation values of 9.1%. The sensor was further validated for the detection of various environmental pollutants, demonstrating its potential as a flexible, reusable and efficient platform for environmental monitoring.
Composites are materials designed to achieve superior mechanical or physical properties, and understanding both their failure and dynamic behavior is essential. Despite numerous past studies on understanding this behavior of composite materials, information on the interrelationship between these two aspects remains limited. The study aims to conduct a process innovation and provide detailed understanding of the effect of fiber orientation on the Graphite epoxy and E-glass epoxy composite laminates failure behavior and natural frequency and the relationship between the failure and dynamic behavior of these two materials. To achieve this, a process innovation of the simulation of failure analysis and vibration analysis of these composite laminates under uniaxial tensile loading was conducted on 8-ply composite laminates under a lamination scheme of (-θ/45/-45/θ/-θ/45/-45/θ), where θ from 0° to 90°. Finite element models for simulation were developed and validated to ensure the reliability and validity of findings in this study are trustworthy and useful. The results show that both failures loads, and natural frequencies are not much affected by the fiber orientation under this lamination scheme. These two behaviors are also identified to be closely related under specific modes of natural frequency. The detailed effects of failure and natural frequency under fiber orientation and its relation are successfully acknowledged. The findings are expected to support the optimization of laminate design and enhance the structural performance of composite materials in engineering applications and contribute to more informed material selection.
This study investigates the effects of various cutting technologies on a 0.25 mm thick ferritic steel, a material widely used in packaging and other lightweight applications. The study provides a comprehensive comparison of four distinct cutting technologies: Laser Cutting, Milling, Electrical Discharge Machining (EDM), and Water Jet Cutting. The research focuses on the impact of these cutting processes on the material’s properties and its performance under uniaxial tension. X-ray diffraction is used to precisely measure the magnitude and distribution of residual stresses along the cut edge in order to correlate them with changes in the material's flow curve, which is critical for accurate mechanical characterization. Furthermore, a laser-scanning microscope was used for detailed morphological analysis of the cut edge and for roughness measurement. To quantify mechanical property changes, microindentation hardness testing was used to assess the degree of work hardening induced by each cutting method. Finally, Digital Imaging Correlation (DIC) was employed to track strain distribution and observe strain field variations.
Copper is a valuable industrial metal, extensively utilized in its pure form due to its excellent electrical and thermal conductivities. It plays a vital role in a wide range of applications, including refrigeration systems, coin and jewelry manufacturing, strain gauges, thermocouples, and more. However, in its ionic form, copper (particularly as Cu 2+ ) can be toxic, especially when present in industrial effluents and wastewater streams. Therefore, the effective adsorption of cupric ions (Cu 2+ ) is a critical environmental and technological concern addressed in this study. From this work, tissue paper pulp waste, chitosan derived from frozen food industry byproducts, and chitosan-coated pulp waste were developed as modified adsorbents for Cu 2+ removal from aqueous solutions. Brunauer–Emmett–Teller (BET) surface area analysis revealed that chitosan exhibited the highest porosity, while the chitosan-coated pulp provided a well-balanced structure with enhanced functional properties. Under controlled experimental conditions, all three materials demonstrated significant Cu 2+ removal efficiency, with the chitosan-coated pulp slightly outperforming the others. These findings highlight the potential of chitosan-coated pulp waste as a low-cost, sustainable, and highly effective adsorbent for the remediation of heavy metal-contaminated wastewater.
Various heat treatments were applied to reduce quench-induced residual stresses while improving the mechanical properties of particle-reinforced aluminum composite. The residual stress distribution of samples quenched in water with different cooling media was measured. The results showed that quenching with the 30% polyethylene glycol quenchant (PAG) yields up to an 86.8% reduction in residual stress magnitude compared with cold-water quenching (CWQ). Still, the tensile properties of samples quenched in 30% polyethylene glycol quenchant were low, with a 12.5% reduction in yield strength. The experimental results show that the uphill quench (UQ) method is an effective means of reducing residual stresses induced by quenching. At the same time, the effect on tensile properties is negligible. Moreover, the study found that combining uphill quenching with short-aging treatment can further improve the residual stress, strength, and fracture toughness of SiCp/Al-Cu-Mg composites.
This work focuses on the pultrusion of pre-consolidated tapes made of virgin polypropylene reinforced with glass fiber. A specially designed laboratory-scale pultrusion line was used, consisting of a heating/forming mold, a cooling mold, and the pulling system. A life cycle assessment was conducted to evaluate the environmental impact of producing a pultruded composite material with a constant cross-section of 100 mm² and a length of one meter. The cradle-to-gate approach was chosen to model the pultrusion process, which involves the three stages mentioned above. The analysis was performed using the CML 2016 method in the LCA for Experts (Sphera) software. The data used in this work to model the cradle-to-gate scenario are mainly derived from experimental measurements taken during the pultrusion process using sensors and from the literature. The specific Energy Consumption (SEC) was calculated for both operational conditions (1.41 MJ/m at v120 to 0.905 MJ/m at v180). Despite the defects found, the samples taken from the pultruded profile showed significant interlaminar shear strength (120 mm/min of 83.7 ± 9.6 MPa compared to 63.5 ± 17.3 MPa at 180 mm/min).
The prediction of sheet failure remains a highly relevant topic in metal forming research, particularly in relation to the experimental and theoretical determination of forming limit curves (FLCs). While the experimental construction of FLCs is a well-established but time-consuming process, theoretical and numerical approaches provide a more efficient alternative. However, their accuracy must be critically assessed, all the time. In this work, the formability of steel sheet with tensile strengths of 1500 MPa is investigated by combining experimental Nakajima tests with theoretical predictions of FLCs. Previous studies, such as models by Abspoel, Swift, Hill etc. have not addressed such high strength levels, where the diffuse and local neck points are quite close, leaving open the question of whether existing approaches remain valid for these materials. To provide a reference baseline, additional tests and calculations were also performed on lower-strength steel sheet (DP800). Our results show that the FLC points can be well estimated by two different theories in the positive quadrant, but there are noticeable differences between the measured and calculated values close to the plane strain point.
An oxygen-free copper has been utilized as a terminal material in the power transistors and their related electric system in the electric mobiles because of its high electric conductivity and excellent engineering durability in high current usage. The high ductility and its low mechanical strength cause large shear droop and increase of fractured surface. In this report, the shearing of oxygen-free copper was carried out using a punch with a mirror-finished surface roughness. Using the punch tip deflection as a parameter, a comparison of shearing characteristics was made between a punch with a nitrided tool surface and an untreated punch. The influence on the formation of the sheared surface was considered from an investigation of the shearing characteristics. When shearing oxygen-free copper with a thickness of 500 µm, it was shown that by providing a punch tip deflection of approximately one-tenth of the thickness in the punch stroke direction, the shear droop could be kept to 10 % or less of the plate thickness and a burnished surface ratio was approximately kept 90 %.
The present study aims to investigate the anisotropic creep behaviour of aluminium alloy 2139 during artificial ageing, through in situ thermomechanical loadings under Electron Backscattered Diffraction (EBSD). EBSD analysis enabled the characterisation of microstructural parameters and the identification of grain misorientations which were further correlated with macroscopic creep strain. In situ analyses were conducted within a Scanning Electron Microscope (SEM) using a micro‑tensile stage that allows simultaneous heating and mechanical loading. Creep tests were performed at 160°C under 50, 100 and 150 MPa along three different orientations in order to investigate the creep behaviour of the alloy. Kernel Average Misorientation (KAM) maps showed a progressive increase of the average KAM values for the different loading conditions, reaching a saturation value after 10 hours. Ex situ tensile tests were conducted on creep‑aged specimens using Digital Image Correlation (DIC). The main mechanical property evolutions (averaged across all orientations) are a 45 % increase in yield stress, a 10 % increase in ultimate tensile stress and a reduction in ductility, characterised by a notable decrease in elongation. Further works will focus on the result repeatability, as well as on the influence of prior deformation on the creep strain.
This study investigated the absorption spectra of rare earth metal (REM) doped polymer composite material, specifically Europium Aluminum-doped Benzyl Methacrylate (Eu-Al/BzMA), which were ascertained from a 0.56-cm bulk sample. The results revealed the most intense peak at 395 nm induced by the Eu 3+ ion absorption. Under 350-nm UV light excitation, Eu-Al/BzMA exhibited sharp red emission at 617 nm corresponding to the 5 D₀→ 7 F₂ transition. The absorption cross sections were determined as 5.62 × 10 -22 cm 2 for the signal and 6.1 × 10 -22 cm 2 for the pump. Collectively, these results demonstrate that Eu-Al/BzMA is a promising gain medium for highly efficient active devices in visible-range applications.
The dendritic microstructure formed during solidification plays a critical role in determining the mechanical properties of aluminum castings. In particular, secondary dendrite arm spacing (SDAS) is strongly influenced by the cooling rate and is closely related to yield strength, ultimate tensile strength, and elongation. However, experimental validation of these relationships requires a consistent methodology for defining cooling rate and linking it to microstructural and mechanical measurements. In this study, an experimental framework was established to investigate the relationships among cooling rate, SDAS, and mechanical properties in aluminum castings. Casting blocks with different thicknesses were fabricated to obtain a wide range of cooling rates. Cooling curves were measured during solidification, and cooling rates were determined using the second derivatives of the cooling curves. SDAS measurements and tensile tests were conducted on specimens extracted from symmetric positions within the casting blocks to ensure equivalent thermal histories. The results showed that the cooling rate–SDAS relationship exhibited a linear trend on a logarithmic scale, consistent with previously reported correlations. Smaller SDAS values were associated with increased yield strength, ultimate tensile strength, and elongation. The agreement between the present results and literature data confirms the validity of the proposed experimental framework for correlating solidification conditions, microstructure, and mechanical properties of aluminum castings.
A consistent kinematic method was developed to calculate a forming limit curve (FLC) for a material with thickness t * 0 from a given FLC pertaining to a different thickness t 0 ≠ t * 0 . The developed method is based on the analysis of the bending strains introduced by the Nakajima test method. To calculate the required strains, an explicit and an implicit procedure are presented. In contrast to its implicit equivalent, the explicit method suffers from an intrinsic error which scales with the material’s gauge and can be quantified by considering the neutral case t * 0 = t 0 . Finally, the developed method predicts a linear relationship between and the material thickness, which is in line with practical experience.
In order to reliably predict a material’s behavior during the forming process, robust calculations with precisely calibrated material models are required. Especially when it comes to mapping phenomena depending on complex interactions of different effects, sophisticated measuring techniques have to be used in order to capture them sufficiently. Springback of sheet metal components is governed by elastic behavior, determined by geometry and current material properties. While well understood for most materials, dual-phase steels are exceptional due to their non-linear elasticity and pronounced kinematic hardening, which strongly affect elastic response. Kinematic hardening is characterized via the Bauschinger coefficient from tension–compression tests. As the Bauschinger effect depends on pre-strain and strain rate, precise crosshead control is essential. Therefore, state-of-the art characterization techniques control the process speed by calculating the crosshead velocity from the pre-set clamping length and strain rate. This method, however, does not account for setup-related influences such as machine stiffness or specimen slippage. Therefore, to improve the characterization accuracy of the Bauschinger effect, an alternative method for crosshead control during the tensile-compression test is introduced and analyzed in this study. To compare this innovative approach with the conventional one, both methods are used to capture the effect of relaxation on the Bauschinger effect with different dual-phase and mild steel. The mentioned novel method is based on the optical strain rate control during tensile tests by Naumann, using Digital Image Correlation with an Aramis setup by ZEISS. The intended pre-strain before load reversal is actively controlled by measuring the strain in situ. After characterizing the material cards for each setup, the resulting Chaboche-Rousselier curves are compared to the experimental ones. The results demonstrate that the applied method provides a reliable proof of concept and achieves precision comparable to, as well as exceeding, the conventional displacement strain rate control method.
During a heat treatment, a material undergoes microstructural changes that result in an alterationof its hardness. In a two-step heat treatment, the material is first adjusted to an initial hardness viaa specified cooling rate. Subsequently, the hardness is reduced through a tempering process, whileits ductility is increased. Depending on the tempering duration, tempering temperature, and initialhardness, different resulting hardness values are obtained. The resulting hardness after a chosen heattreatment has thus far been difficult to predict. This work employs symbolic regression to develop amodel that predicts the hardness evolution of 42CrMo4 steel as a function of cooling rate, temperingduration, and tempering temperature. By describing the model with few parameters, it has alsobeen demonstrated that cooling rates and tempering temperatures leading to a target hardness canbe determined. The overall model achieves a coefficient of determination of R2 = 98.50 % for knownexperimental data and a combined coefficient of determination of R2 = 93.13 % for previouslyunknown cooling rates (forward) and previously unattained resulting hardness values (inverse).Our work shows that the resulting hardness of 42CrMo4 can be predicted using a small numberof parameters. This work is anticipated to establish a foundation for further research endeavors.For instance, the approach using symbolic regression can be further adapted to identify physicallyinterpretable constants. Furthermore, the model description offers the possibility of coupling witha simulation model to accurately predict the hardness of a component.
Direct compounding of long fiber thermoplastic (LFT-D) materials in compression molding are two complex processes in series linked by the plastificate. Continuous compounding and sequential compression create a time-dependent property progression along the extrusion direction of the plastificate. Under variation of secondary parameters, extruder die temperature, and die height of the LFT-D line, samples of plastificates, flow fronts and plates are manufactured and characterized. The plastificate density progression along the extrusion direction is primarily influenced by the temperature of the die. Lofting of the plastificate is higher at high temperatures while the density difference along the extrusion direction is lower. This density difference is known to influence fiber orientations and mechanical properties. The flow front of the material filling the mold is skewed because of the density difference. We show that the skewness is mainly influenced by the die height and is lower at high die heights. The fiber content distribution in the plate is discussed and found to be influenced by the length of the plastificate which is in turn determined by the secondary parameters. These secondary parameters of the LFT-D line can play a role in process optimization once the primary parameters are selected. This work provides clues and observations of principles for such optimizations.
This study reports the synthesis and comprehensive characterization of V 2 ZnC-PVA saturable absorbers (SAs) fabricated via solution-casting methods. The thin films were examined for their structural, chemical, and optical properties to evaluate their suitability for ultrafast photonic applications. Surface morphology and thickness were assessed using field emission scanning electron microscopy (FESEM) and 3D laser scanning microscopy, while elemental composition and crystallinity were confirmed through energy-dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD). Raman spectral analysis, through its molecular vibration signatures, verified both the preservation of the MAX-phase structure and the overall stability of the films. Optical characterization revealed distinct behaviours: linear absorption measurements confirmed high transparency with adjustable absorption profiles, whereas nonlinear experiments conducted with a twin-balanced detector demonstrated pronounced saturable absorption, achieving modulation depths above 12 % and saturation intensities in the order of kW·cm -2 . Together, these findings demonstrate that V 2 ZnC-PVA saturable absorbers are suitable for ultrafast photonics, especially in passive Q-switching and mode-locking, because of their strong nonlinear response, uniform morphology, and superior resistance to optical damage with a high damage threshold.
In carbon-free technologies, thin-walled components with microchannels from ultra-thin sheets, such as bipolar plates, cooling plates, and heat exchangers, are widely utilized. Using such components made of high-strength aluminum alloys further reduces the required wall thickness, thereby enhancing their lightweight potential. However, conventional forming methods for ultra-thin sheets, including elastomer-based deep drawing and hydroforming, are limited by process-induced phenomena such as springback, geometrical inaccuracies and reduced formability as well as localized thinning, which can necessitate a higher wall thickness or the use of a lower strength grade alloy. Gas-based hot sheet metal forming of high-strength aluminum alloys is introduced to improve formability and geometrical accuracy. In the present study, an isothermal, gas-based hot sheet metal forming process is developed for forming microchannels from AlMg3 alloy sheets with a thickness of 0.4 mm. A 100 mm × 100 mm blank is heated to 530 °C and formed under nitrogen gas pressure into a heated die featuring various channel geometries. The effects of blank-holder force, maximum gas pressure, wall angle, channel radius, and maximum channel depth on thinning and form filling are investigated. Additionally, the grain size of the final component is analyzed. A full form filling can be reached under a forming pressure of 200 bar. The thinning is dependent on the micro channel geometry and reaches a maximum of 29 % for a channel depth of 1 mm. The grain size increases during the forming process, dependent on the introduced strain into the material. The proposed method enables forming of components without fracture and with high geometrical accuracy.
The six independent axes available for free-form bending enable the production of complex three-dimensional bent tube and profile geometries. In industrial environments, only tangential bending strategies are currently used, which means that the bending head is always positioned parallel to the cross-section of the tube in the current bending section. Therefore, the individually controllable axes make it possible to apply other, non-tangential bending strategies. In so-called overbending, the bending head is rotated more in comparison to tangential bending. However, in order to ensure that the bending radius does not change compared to tangential bending, the translational deflection of the bending head must be reduced at the same time. In contrast, the bending head is rotated less during underbending and the translational deflection is increased. Overbending and underbending offer the possibility of improving the mechanical properties while maintaining the same bending geometry. These strategies allow the components to be optimized for individual load cases. As part of this work, a structural component was produced multiple times using free-form bending. Both conventional tangential bending strategies as well as innovative overbending and underbending strategies were applied. The mechanical stiffness of the bent components was then examined on a test bench. The influence of the bending strategy on the cross-sectional change in the bent area was investigated by using a tactile coordinate measuring machine. Furthermore, residual stress measurements were performed on the bent tubes, which allowed the different mechanical behavior of the tangentially bent, overbent and underbent tubes to be explained.
Predicting the final shape of automotive structural components after springback is a challenge to the inclusion of high strength aluminum alloys into the vehicle body-in-white. Complex deformation paths and reverse loading of sheet material during forming operations can induce significant Bauschinger effects and kinematic hardening behaviour. Capturing the through-thickness stress gradient is critical when predicting springback, which is governed by tooling dynamics, frictional forces, and material plasticity. In this study, the anisotropic behaviour of a AA6xxx-T4 aluminum alloy was characterized to calibrate a BBC2005 yield function, kinematic hardening effects were characterized through a novel uniaxial compression-tension technique, and a technology demonstrator U-shaped rail component was formed and scanned to assess the final shape after springback. Multiple model variations were analyzed in AutoForm R12, modifying simulation control parameters, binder loading condition (uniform vs. column), friction model (Coulomb vs. TriboForm), and hardening model (isotropic vs. kinematic). The use of column binder loading paired with TriboForm friction model provided the most significant improvement for thinning and springback prediction accuracy with kinematic hardening being a second order effect compared to accounting for friction and binder force.
