Modulus In Range Research Articles

A tissue-engineered neural interface with photothermal functionality.

Neural interfaces are well-established as a tool to understand the behaviour of the nervous system via recording and stimulation of living neurons, as well as serving as neural prostheses. Conventional neural interfaces based on metals and carbon-based materials are generally optimised for high conductivity; however, a mechanical mismatch between the interface and the neural environment can significantly reduce long-term neuromodulation efficacy by causing an inflammatory response. This paper presents a soft composite material made of gelatin methacryloyl (GelMA) containing graphene oxide (GO) conjugated with gold nanorods (AuNRs). The soft hydrogel presents stiffness within the neural environment range of modulus below 5 kPa, while the AuNRs, when exposed to light in the near infrared range, provide a photothermal response that can be used to improve the spatial and temporal precision of neuromodulation. These favourable properties can be maintained at safer optical power levels when combined with electrical stimulation. In this paper we provide mechanical and biological characterization of the optical activity of the GO-AuNR composite hydrogel. The optical functionality of the material has been evaluated via photothermal stimulation of explanted rat retinal tissue. The outcomes achieved with this study encourage further investigation into optical and electrical costimulation parameters for a range of biomedical applications.

A Novel Variable Stiffness and Tunable Bending Shape Soft Robotic Finger Based on Thermoresponsive Polymers

In this study, a soft robotic finger with variable stiffness and tunable bending shape capability is proposed. The finger employs shape memory polymers (SMP) as the variable stiffness element and polyimide (PI) electrothermal films as the flexible heaters for segmental heating. SMP and PI electrothermal films constitute the variable stiffness structure. The SMP part exhibits a reversible transition from glass state to rubber state during the heating/cooling process. The whole transition process results in an elastic modulus range of three orders of magnitude. The finger can obtain multiple bending shapes and adapt to the outer contours of diverse objects because of the segmental stiffness modulation capability of the variable stiffness structure. Supercoiled polymer artificial muscles (SCPAMs) are used as actuators for the finger. SMPs and SCPAMs are thermoresponsive and can be activated by thermal heating with electricity, making the whole finger structure compact. Experimental results show that the stiffness of the finger at room temperature (25 °C) is 10.54 times that at 70 °C when the actuators are on. The performance of the finger is further validated via the sequential motion demonstration and grasping tests with variable stiffness and bending shape control capabilities, showing the proposed design’s potential in soft grippers and robotic design.

Characterization of microstructures and micromechanical properties of naturally generated rust layer in 60-year old reinforced concrete

The mechanical properties of steel corrosion products reported in the literature present a great dispersion. The present study aims to explore the mechanical behavior of naturally generated corrosion products at the microscale level in relation with typical microstructural features. Microstructural characterization was performed on corrosion products by nano-indentation, Raman micro-spectrometry, scanning electron microscopy and electron backscatter diffraction. The Young’s modulus and nanohardness range between 66.5 and 158.1 GPa and 2.97–11.71 GPa, respectively. The various morphologies and corresponding mechanical properties of goethite, maghemite and magnetite have finally been discussed, clarifying the influences of porosity, crystallinity and grain size on the mechanical properties.

Stable a-CSi:H films with a wide range of modulus of elasticity and low internal stress

Amorphous hydrogenated silicon carbide (a-CSi:H) thin films were deposited by plasma-enhanced chemical vapor deposition using tetravinylsilane as organosilicon precursor. The mechanical properties of the thin films, namely the modulus of elasticity, hardness, and elastic recovery parameter, were determined by nanoindentation, as well as the internal stresses by scanning electron microscopy and optical profilometry. It was found that the modulus of elasticity increased from 10 to 137 GPa with increasing power (2–150 W) delivered to plasma, while the hardness increased from 1.5 to 14.5 GPa. This improvement in mechanical properties with increasing energy delivered to the plasma is related to greater fragmentation of the precursor which led to an increase in the crosslinking of the material network. The compressive internal stresses in the films reached low values of −0.04 to −0.2 GPa with increasing power (2–75 W) and an acceptable −0.5 GPa for 150 W. The elastic recovery parameter decreased with increasing power from 0.86 to 0.64, i.e., the thin films behaved more plasticity with increasing power. The modulus of elasticity and hardness were investigated in terms of the aging of the films for a period of 6 years when samples were stored under ambient conditions. No significant changes in these properties were observed. However, minor changes were observed in the indentation curves obtained for the 2 W and even less for the 10 W samples. Small changes were then also observed for the elastic recovery parameter, whose value for these samples partially decreased which may be related to postdeposition oxidation. No changes in internal stress values over time were observed. The wide range of mechanical properties of stable a-CSi:H films with low internal stress increases their application potential and their wide use as materials with tailored properties from polymer-like to tough material.

Development and systematic characterization of GelMA/alginate/PEGDMA/xanthan gum hydrogel bioink system for extrusion bioprinting

Gelatin methacryloyl (GelMA)/alginate-based hydrogels have shown great promise in bioprinting, but their printability is limited at room temperature. In this paper, we present our development of a room temperature printable hydrogel bioink by introducing polyethylene glycol dimethacrylate (PEGDMA) and xanthan gum into the GelMA/alginate system. The inclusion of PEGDMA facilitates tuning of the hydrogel's mechanical property, while xanthan gum improves the viscosity of the hydrogel system and allows easy extrusion at room temperature. To fine-tune the mechanical and degradation properties, methacrylated xanthan gum was synthesized and chemically crosslinked to the system. We systematically characterized this hydrogel with attention to printability, strut size, mechanical property, degradation and cytocompatibility, and achieved a broad range of compression modulus (∼10–100 kPa) and degradation profile (100% degradation by 24 h–40% by 2 weeks). Moreover, xanthan gum demonstrated solubility in ionic solutions such as cell culture medium, which is essential for biocompatibility. Live/dead staining showed that cell viability in the printed hydrogels was over 90% for 7 days. Metabolic activity analysis demonstrated excellent cell proliferation and survival within 4 weeks of incubation. In summary, the newly developed hydrogel system has demonstrated distinct features including extrusion printability, widely tunable mechanical property and degradation, ionic solubility, and cytocompatibility. It offers great flexibility in bioprinting and tissue engineering.

SIMULATION OF VIBRATORY PLATE INTERACTION WITH THE GROUND SURFACE

The paper presents a three-mass rheological model of the system "soil – vibration plate base – vibration plate frame". The rheological model makes it possible to reproduce different modes of interaction between the vibratory plate base and soil: with different types of plate decoupling and without decoupling. We verify this model by comparing the experimental values of the vertical oscillation span of the base and frame of the Zitrek CNP 20 vibrating plate with the previously calculated values. As a whole, the calculated values of the span of vertical oscillations of the base and frame of the Zitrek CNP 20 vibrating plate correlate with the experimental data in the range of the dynamic modulus of soil deformation of 13…30 MPa. During the experiment we used the rheological model and obtained results are as follows: the mass of the vibrating plate (50; 150; 250; 350; 450; 550; 650; 750 kg), the coefficient of the elastic resistance of soil (30; 60; 90; 120 MN / m), and the coefficient of viscous resistance of soil (100; 200; 300 kN • s / m). The total number of combinations of parameters was 96. The processed results of the computational experiment provide the regression dependences for calculating the maximum soil reaction force, the time of soil loading (increasing the values of the reaction force of soil) t1, and the time of soil unloading (decrease the values of the reaction force of soil) t2. The simulation results show that, within one exposure cycle, the soil loading time t1 is less than the soil unloading time t2. The ratio t1/t2 is influenced by the weight of the vibratory plate, as well as the factors of elastic and viscous resistance of soil. This feature (t1/ t2  1) is typical for both vibratory rollers and rammers, which is confirmed by the results of the relevant experimental studies. The obtained regression dependences of parameters Fs, t1, and t2 on the vibratory plate mass and the factors of elastic and viscous resistance of soil are important for calculating the distribution of stresses and strains on the depth of the compacted soil.

Modelling and verification of a novel bi-material mechanical metamaterial cellular structure with tunable coefficient of thermal expansion

The tunable thermal expansion characteristic of metamaterials is beneficial to solve the problems caused by drastic temperature changes. Here, we propose a novel bi-material mechanical metamaterial cellular structure (NBMCS) that can adjust the coefficient of thermal expansion (CTE). Under some parameters restrictions, the structure can realize the regulation of its CTE in a wide range from -115 ppm/℃ to 83.6 ppm/℃ with Al alloy/Low carbon steel combination. A general thermoelasticity equation that builds the relationship among the temperature, the external force, and the displacement is derived, which is then assembled into a theoretical model of NBMCS. Through theoretical analysis and numerical simulations, the underlying mechanism among the CTE of NBMCS, geometric parameters, elastic modulus ratio, and CTE ratio is revealed. Experiments are carried out based on industrial camera and DIC method, which verify the theoretical modelling. Finally, the tunable range of CTE and elastic modulus for three different material combinations are compared. • A novel metamaterial structure with tunable coefficient of thermal expansion. • A general thermoelasticity equation for the structure is established. • Simulation and experiments are carried out to verify the theoretical modeling.

So-EAGlove: VR Haptic Glove Rendering Softness Sensation With Force-Tunable Electrostatic Adhesive Brakes

Haptic gloves allow the players to feel the virtual world more realistically by providing force feedback. At present, haptic gloves are mainly driven by conventional motors, and for them, being lightweight, low cost, low in power consumption, and intrinsically safe to operators are challenging. Here, we designed a haptic glove (So-EAGlove) integrating a flexible electrostatic adhesive brake to resist human fingers with a tunable braking force and render a softness sensation. This glove weighs only 51 g, but is capable of simulating objects in a large range of Young's modulus from 540 Pa to 5.4 MPa. The electrostatic adhesive brake costs only approximately 2.43 mW during operation, i.e., more than three days powered by a small button battery. We built a feedforward control model and evaluated its performance. Experimental results show that this glove can generate an accurate force to follow the force-displacement profile of the corresponding real objects. The error is less than 7%, barely noticeable by the subjects. The subjective tests also demonstrate that little statistical difference exists between the real objects and the virtual objects for the subjects.

Digital Light Processing 3D Printing of Gyroid Scaffold with Isosorbide-Based Photopolymer for Bone Tissue Engineering.

As one of the most transplanted tissues of the human body, bone has varying architectures, depending on its anatomical location. Therefore, bone defects ideally require bone substitutes with a similar structure and adequate strength comparable to native bones. Light-based three-dimensional (3D) printing methods allow the fabrication of biomimetic scaffolds with high resolution and mechanical properties that exceed the result of commonly used extrusion-based printing. Digital light processing (DLP) is known for its faster and more accurate printing than other 3D printing approaches. However, the development of biocompatible resins for light-based 3D printing is not as rapid as that of bio-inks for extrusion-based printing. In this study, we developed CSMA-2, a photopolymer based on Isosorbide, a renewable sugar derivative monomer. The CSMA-2 showed suitable rheological properties for DLP printing. Gyroid scaffolds with high resolution were successfully printed. The 3D-printed scaffolds also had a compressive modulus within the range of a human cancellous bone modulus. Human adipose-derived stem cells remained viable for up to 21 days of incubation on the scaffolds. A calcium deposition from the cells was also found on the scaffolds. The stem cells expressed osteogenic markers such as RUNX2, OCN, and OPN. These results indicated that the scaffolds supported the osteogenic differentiation of the progenitor cells. In summary, CSMA-2 is a promising material for 3D printing techniques with high resolution that allow the fabrication of complex biomimetic scaffolds for bone regeneration.

Sealing capacity evolution of gypsum salt caprocks under multi-cycle alternating stress during operations of underground gas storage

Caprock sealing ability is one of the key geological factors to ensure the stable and safe operation of the underground gas storage (UGS). Gypsum salt rock is the high-quality caprock for oil and gas reservoirs, however, the effect of cyclic stress on its sealing capacity is still unclear, which restricts the construction progress of this kind of UGS. Therefore, taking the H UGS in the Sichuan Basin in China as an example, this paper analyzes the initial sealing capacity of gypsum salt caprock using cast thin section, conventional physical property test, nuclear magnetic resonance and breakthrough pressure tests. On this basis, study the variation characteristics of physical and mechanical parameters of gypsum salt caprock under cyclic stress using cyclic stress loading and unloading experiment, and then analyze the evolution law of its sealing capacity. The results show that gypsum salt caprocks of H UGS can be used as a good tight caprock with the porosity less than 1.0%, permeability less than 0.005 mD, breakthrough pressure greater than 6.0 MPa and triaxial compressive strength greater than 210 MPa. In addition, the physical properties of gypsum salt caprock become worse and the sealing capacity increases under cyclic stress, and physical and mechanical changes of gypsum salt caprock mainly occur in the first 30 cycles accounting for about 75%. Moreover, with the increase of cycles, the Poisson's ratio increases by 88% while the change range of elastic modulus is only 6.4%, indicating that gypsum salt caprocks mainly expands laterally and still maintain good elasticity. However, when the cycle times reach a certain threshold of 1002, the cumulative plastic strain of gypsum salt rock will become larger and larger until fracture. And the gypsum salt caprocks can be effective cover in the 184 cycles of loading and unloading with the maximum pressure threshold of 18 MPa and minimum pressure threshold of 1 MPa. This research results can provide theoretical guidance for cap rock stability analysis and operation parameter design of gas reservoir.

Effect of Material Distribution in the Unit Cell on Effective Thermal Conductivity and Young's Modulus of Cellular Structure

Abstract Effective thermal conductivity and Young's modulus of periodic unit cell geometries are widely studied in the literature. This paper compares and contrasts strut-based unit cells against surface-based unit cells obtained by subtracting spheres from a solid cube. In order to understand the reason for the difference in the behavior of effective thermal conductivity of surface-based and strut-based unit cell geometries and the difference in the behavior of Young's modulus of surface-based and strut-based unit cell geometries, the effect of material distribution on effective thermal conductivity and Young's modulus is studied here. The material in the unit cell is varied in two ways, i.e., by changing the material distribution on the cell wall (partially closed unit cell) and changing the material distribution across the strut of unit cell geometry. It is found that the distribution of material on the wall of the unit cell improves the effective thermal conductivity and Young's modulus. In contrast, a narrow cross-section area in the unit cell reduces the effective thermal conductivity and Young's modulus. Using the studied effect of material distribution on effective thermal conductivity and Young's modulus, the reason for the difference in properties of surface-based and strut-based unit cell geometry is qualitatively explained. Partially closed unit cell geometries introduced here for studying the effect of material distribution on cell walls give a wide range of effective thermal conductivity and Young's modulus for the same porosity with a change in pore opening ratio.

An electrorheological elastomer with marigold-like TiO2 particles towards large tunable range of storage modulus

The tunable range of storage modulus is closely related to the performance of electrorheological elastomers (EREs). Previous studies have made great progress by adjusting the chemical composition of dielectric particles, properties of matrix and interface properties of particles/matrix, while the range of modulus variation of EREs is still narrow when the mass fraction of particles is relatively low. In this study, marigold-like TiO2 particles with complicated surface nanostructure were synthesized via a solvothermal method, and the EREs were prepared by using these particles as dispersion phase and silicone rubber as matrix. The storage modulus. The results illustrate that EREs containing marigold-like TiO2 particles (M-EREs) have large field-induced storage modulus (103.8 kPa) and significant relative ER effect (69.5%). The obvious performance results from the high crosslink density and strong friction between matrix and particles. These observations indicate a promising way to enhance the performance of EREs.

Mechanical and Thermal Properties of Functionally Graded Polyolefin Elastomer Foams.

In this work, uniform and graded polyolefin elastomer (POE) foams were prepared using a single-step technology based on a fixed chemical blowing agent (azodicarbonamide) concentration of 4 phr (parts per hundred rubber). The effect of molding temperature, including the average temperature (Tavg) and temperature difference (ΔT), on the foams’ morphology, mechanical properties (tension, compression and hardness) and thermal conductivity was investigated. Two series of samples were produced by fixing Tavg with different ΔT or setting different ΔT, leading to different Tavg. The morphological analyses showed that two or three regions inside the foams were produced depending on the molding conditions, each region having different cellular structure in terms of cell size, cell density and cell geometry. The results obtained for the conditions tested showed a range of density (0.55–0.72 g/cm3), tensile modulus (0.44–0.70 MPa) and compression elastic modulus (0.35–0.71 MPa), with a thermal conductivity between 0.125 and 0.180 W/m.K. Based on the information provided, it can be concluded that the foam’s properties can be easily controlled by the cellular structure and that graded samples are more interesting than uniform ones, especially for thermal insulation applications, such as packaging, construction, transportation, automotive and aerospace industries.

Microstructural image based convolutional neural networks for efficient prediction of full-field stress maps in short fiber polymer composites

The increased demand for superior materials has highlighted the need of investigating the mechanical properties of composites to achieve enhanced constitutive relationships. Fiber-reinforced polymer composites have emerged as an integral part of materials development with tailored mechanical properties. However, the complexity and heterogeneity of such composites make it considerably more challenging to have precise quantification of properties and attain an optimal design of structures through experimental and computational approaches. In order to avoid the complex, cumbersome, and labor-intensive experimental and numerical modeling approaches, a machine learning (ML) model is proposed here such that it takes the microstructural image as input with a different range of Young's modulus of carbon fibers and neat epoxy, and obtains output as visualization of the stress component S11 (principal stress in the x-direction). For obtaining the training data of the ML model, a short carbon fiber-filled specimen under quasi-static tension is modeled based on 2D Representative Area Element (RAE) using finite element analysis. The composite is inclusive of short carbon fibers with an aspect ratio of 7.5 that are infilled in the epoxy systems at various random orientations and positions generated using the Simple Sequential Inhibition (SSI) process. The study reveals that the pix2pix deep learning Convolutional Neural Network (CNN) model is robust enough to predict the stress fields in the composite for a given arrangement of short fibers filled in epoxy over the specified range of Young's modulus with high accuracy. The CNN model achieves a correlation score of about 0.999 and L2 norm of less than 0.005 for a majority of the samples in the design spectrum, indicating excellent prediction capability. In this paper, we have focused on the stage-wise chronological development of the CNN model with optimized performance for predicting the full-field stress maps of the fiber-reinforced composite specimens. The development of such a robust and efficient algorithm would significantly reduce the amount of time and cost required to study and design new composite materials through the elimination of numerical inputs by direct microstructural images.

Ultra-High Modulus Hydrogels Mimicking Cartilage of the Human Body.

The human body is comprised of numerous types of cartilage with a range of high moduli, despite their high hydration. Owing to the limitations of cartilage tissue healing and biological grafting procedures, synthetic replacements have emerged but are limited by poorly matched moduli. While conventional hydrogels can achieve similar hydration to cartilage tissues, their moduli are substantially inferior. Herein, triple network (TN) hydrogels are prepared to synergistically leverage intra-network electrostatic repulsive and hydrophobic interactions, as well as inter-network electrostatic attractive interactions. They are comprised of an anionic 1st network, a neutral 2nd network (capable of hydrophobic associations), and a cationic 3rd network. Collectively, these interactions act synergistically as effective, yet dynamic crosslinks. By tuning the concentration of the cationic 3rd network, these TN hydrogels achieve high moduli of ≈1.5 to ≈3.5MPa without diminishing cartilage-like water contents (≈80%), strengths, or toughness values. This unprecedented combination of properties poises these TN hydrogels as cartilage substitutes in applications spanning articulating joints, intervertebral discs (IVDs), trachea, and temporomandibular joint disc (TMJ).

Accuracy analysis of modulus results considering the whole process of modulus back-calculation—based on GPR and FWD

• The numerical hypothesis model was corrected by combining GPR and FWD. • The applicability of different regression models for deflection basins was clarified. • The sensitivity of modulus back-calculation results was analyzed. • The accuracy of the modulus back-calculation result has been significantly improved. In this study, based on the consideration of the whole process of modulus back-calculation, the measured deflection basins of asphalt pavements under dynamic loading were obtained by using the falling weight deflectometer (FWD), and the parameters such as thickness, initial modulus range, and Poisson's ratio of each structural layer in the numerical hypothesis model were corrected based on the detection results of the thickness and damage status of each structural layer by the ground-penetrating radar (GPR). At the same time, mathematical regression models such as the Exponential regression model, Parabolic regression model, and Sigmoid regression model were used to fit the theoretical deflection basin, and the accuracy of the relationship model between the deflection basin parameters and the pavement structural parameters constructed after fitting the theoretical deflection basin by different regression models were compared. It is observed that the change in the numerical hypothesis model and the regression model of the theoretical deflection basin can have a significant impact on the modulus back-calculation results. The research results show that when the numerical hypothesis model and the regression model are not corrected and optimized, the absolute value of the relative error between the back-calculation modulus and the dynamic modulus of the asphalt layer obtained in the laboratory test is 64 %. After correcting the numerical hypothesis model and fitting the deflection basin with the Sigmoid regression model, the relative error is within ±4 %. In summary, it is an important method to improve the accuracy of modulus back-calculation by correcting the numerical hypothesis model and optimizing the regression model of the deflection basin.

Modulus backcalculation methodology based on full-scale testing road and its rationality and feasibility analysis

ABSTRACT The objective is to propose a new methodology of modulus backcalculation and analyse its rationality and feasibility. Firstly, the features and advantages of the proposed are summarised. Secondly, a total of 130 sets of deflection basinswere collected and the modulus was backcalculated. Meanwhile, the temperatures of different asphalt layers were monitored. Subsequently, the simple performance test (SPT) was used to establish the master curve model. The dynamic modulus of different asphalt mixtures of falling weight deflector’s load frequency and real test temperature was predicted. Following, the backcalculated modulus was compared with the SPT modulus for verifying its ability of reflecting the material properties. Furthermore, the rationality of the backcalculated modulus is verified, as well as its ability to distinguish between different sections. Lastly, the efficiency, success rate and stability of the proposed method are statistically analysed. Results show that the ratios of the backcalculated modulus to the SPT modulus range from 0.9 to 1.2. The proposed method can process about 100 measured deflection basins per minute and its success rate exceeds 80%. The coefficient of variation of the effective modulus does not exceed 15%. The proposed method has high rationality and feasibility meeting the requirements of engineering applications.

A structural approach to 3D-printing arterial phantoms with physiologically comparable mechanical characteristics: Preliminary observations.

Pulse wave behavior is important in cardiovascular pathophysiology and arterial phantoms are valuable for studying arterial function. The ability of phantoms to replicate complex arterial elasticity and anatomy is limited by available materials and techniques. The feasibility of improving phantom performance using functional structure designs producible with practical 3D printing technologies was investigated. A novel corrugated wall approach to separate phantom function from material properties was investigated with a series of designs printed from polyester-polyurethane using a low-cost open-source fused filament fabrication 3D printer. Nonpulsatile pressure-diameter data was collected, and a mock circulatory system was used to observe phantom pulse wave behavior and obtain pulse wave velocities. The measured range of nonpulsatile Peterson elastic strain modulus was 5.6–19 to 12.4–33.0 kPa over pressures of 5–35 mmHg for the most to least compliant designs respectively. Pulse wave velocities of 1.5–5 m s−1 over mean pressures of 7–55 mmHg were observed, comparing favorably to reported in vivo pulmonary artery measurements of 1–4 m s−1 across mammals. Phantoms stiffened with increasing pressure in a manner consistent with arteries, and phantom wall elasticity appeared to vary between designs. Using a functional structure approach, practical low-cost 3D-printed production of simple arterial phantoms with mechanical properties that closely match the pulmonary artery is possible. Further functional structure design development to expand the pressure range and physiologic utility of dir"ectly 3D-printed phantoms appears warranted.

Thermomechanical Reliability Investigation of Carbon Nanotube Off-Chip Interconnects for Electronic Packages

This article investigates the mechanical reliability benefits of carbon nanotube (CNT) off-chip interconnects for future electronic packages. Finite-element analysis (FEA) of a silicon chip attached to an organic substrate showed that CNT off-chip interconnects with an isotropic modulus of 1 MPa reduced the principal stresses in the silicon chip ~71%–93% compared with lead-free solder balls without underfill. In addition to reducing chip stresses, chip warpage was essentially eliminated by utilizing CNT interconnects compared with solder balls. Parameters of importance for the implementation of CNTs as interconnects such as CNT modulus and height were investigated with finite-element analysis. It was found that chip stresses increase with increasing CNT modulus, but for the modulus range reported in the literature and examined here (0.1–500 MPa), chip stresses were much less than packages utilizing solder balls. Due to the structure and morphology of CNT forests, the different material model types of fully isotropic versus transversely isotropic that can be used to model CNT interconnects were investigated. While the models yielded similar mechanical behavior in the finite-element analyses, the isotropic CNT model was mechanically conservative and simpler to implement and, therefore, sufficient for future thermomechanical reliability studies. To further demonstrate the thermomechanical reliability benefits, silicon chips with CNT off-chip interconnects were fabricated and assembled to organic substrates and subjected to cyclic thermal shock testing. During testing, the daisy chain circuit containing CNT interconnects survived 1660 cycles, demonstrating that CNT interconnects mechanically decouple the chip from the substrate and, therefore, reduce chip stresses caused by coefficient of thermal expansion (CTE) mismatch.

Elastic mechanical property hybridization of configuration-varying TPMS with geometric continuity

Hybrid design is an effective approach to construct functional mechanical metamaterials. In this study, a periodic hybrid method for the TPMS (triply periodic minimal surface) structures is proposed, maintaining the original surface connectivity and structural strength. It is implemented by the combination of implicit function Ψ(x,y,z) and transition function ηx,y,z of the TPMS governing equation. Furthermore, three classical TPMS, i.e., P (Schwarz Primitive), IWP (Schoen I-WP) and FRD (Schoen F-RD), are represented to study the elastic properties of hybridizations using FE (Finite Element) computational method and experiments. Through the RVE-based (Representative Volume Element) homogenization method, it is demonstrated how hybridization of TPMS expands the designable range of elastic modulus. In addition, the elastic properties of the hybridizations, such as axial modulus, diagonal modulus and anisotropy, etc., can be quantificationally tailored by turning the formal parameters of TPMS. This study can be considered as a foundational contribution for the advancement of hybrid TPMS metamaterials.