Mechanical Behavior Of Different Types Research Articles

Predicting mechanical behavior of different thin-walled tubes using data-driven models

The mechanical behavior of thin-walled tubes holds great significance in various engineering applications, ranging from aviation to civil engineering. This study introduces an innovative approach by utilizing machine learning techniques such as Gaussian Process Regression (GPR), Regression Trees (RTs), Artificial Neural Networks (ANNs), and Support Vector Machines (SVMs) to build data-driven models for predicting the mechanical behavior of different types of thin-walled tubes. To achieve this, we gather datasets encompassing various parameters, including material properties, pressure, and displacement. The dataset is a MATLAB array with dimensions of 2800×4. We partitioned the datasets into a training set (70 %, 1960 samples), a validation set (15 %, 420 samples), and a testing set (15 %, 420 samples). The R-squared values for the validation set are as follows: GPR (0.93), RT (0.88), ANN (0.84), and SVM (0.83). For the test set, the R-squared values are: GPR (0.80), RT (0.79), ANN (0.86), and SVM (0.82). Employing these machine learning techniques, we develop models that can predict mechanical properties for each tube category, such as compressional behavior and impact force. These models demonstrate promising accuracy and generalizability, making them valuable tools for engineering design and analysis.

Characterization of mechanical behavior of different types of masonry with a detailed investigation of full-field strain using digital image correlation

This article presents an experimental study on the mechanical characterization of three different types of masonry: burnt clay bricks, fly ash bricks, and autoclaved aerated concrete (AAC) blocks, with a detailed focus on strain distribution and failure mechanism. The specimens were subjected to direct and diagonal compression loading, and the stress–strain curves and failure modes were studied. Digital image correlation (DIC) was used to obtain full-field strain data, allowing for detailed analysis of failure mechanisms, tracking of crack propagation, and examination of other intricate details. The DIC analysis showed that in burnt clay brick and fly ash brick masonry, failure under compression was initiated by the tensile splitting of the brick, while in AAC block masonry, it was initiated by the tensile splitting of the mortar. Additionally, the study identified that the failure modes under diagonal compression were different for each type of masonry, with bed joint sliding being the dominant failure mode in fly ash brick and AAC block masonry. In contrast, the failure mode in burnt clay brick masonry was due to vertical splitting along the loaded diagonal. In the diagonal compression test, the shear strain along both diagonals was negligible, and principal strain directions were observed to be aligned along the two diagonals.

The importance of polyurethane/carbon nanotubes composites fabrication method to mimic mechanical behavior of different types of soft tissues

The importance of polyurethane/carbon nanotubes composites fabrication method to mimic mechanical behavior of different types of soft tissues

Meso-Mechanical Simulation of the Mechanical Behavior of Different Types of Steel Fibers Reinforced Concretes

Introducing steel fibers into traditional concrete can improve its mechanical properties and crack resistance, but few studies have considered how the steel fiber shape and the bond-slip effect between fibers and matrix affect the mechanical behavior of concrete. This paper establishes a three-dimensional representative volume element (3D RVE) of steel fiber-reinforced concrete (SFRC) with random distribution, different shapes, and different interfacial strengths of steel fibers using Python, Abaqus and Hypermesh. Uniaxial tensile behaviors and failure modes of the SFRC are systematically simulated and analyzed. The results show that when the interfacial strength of steel fiber/concrete is changed from 1 to 3 MPa, the tensile strength of the SFRC increases accordingly. When the interfacial strength is greater than 3 MPa, it has no effect on tensile strength. Additionally, if the interfacial strength is 1 MPa, the tensile strength of the SFRC with end-hook steel fibers is increased by 7% when compared to the SFRC with straight steel fibers, whereas if the interfacial strength reaches 2.64 MPa (strength of pure concrete), the fiber shape has little effect on the tensile strength of the SFRC. Moreover, the simulation results also show that interfacial damage dominates when the interfacial strength is less than 1 MPa, and the crack propagation rate in the end-hook steel fiber-modified SFRC is lower than that in a straight steel fiber-modified SFRC. Therefore, this research reveals that using end-hook steel fibers can improve the strength of the SFRC under low interfacial strength, but the ideal strength of the SFRC can be achieved only by using straight fibers when the interfacial strength between steel fibers and concrete is relatively high.

Modeling of counter-bore and counter-sink screw lap joints

This paper presents an analytical approach to predict the mechanical behavior of different types of screw lap shear joints using a spring-mass model. The spring-mass model captures the axial, bending, bearing, and shear stiffnesses of the components and their masses at the joint. The springs in the model represent the stiffness arising from each of these modes of deformation. We derive the expressions of the individual stiffnesses analytically and use the spring-mass model to obtain the overall joint stiffness. We show that this joint stiffness accurately predicts the experimentally observed mechanics of counter-bore and countersink screw lap joints. The experimental validation is carried out in nine different joint configurations. The analytical model is also validated with the aid of linear finite element analysis. Furthermore, the influence of individual stiffness components on the overall joint behavior is studied by varying the thickness and width of the plates.

Numerical and experimental investigation on the effects of mesostructures on the mechanical behavior and failure pattern in concrete

To quickly and accurately predict the macroscopic mechanical behavior of different types of concrete and find mesostructures with excellent properties, a simple and efficient two-dimensional (2D) numerical mesostructure model of concrete was established and calculated by CalculiX finite element (FE) software. Then, a series of simulations and experiments were performed through the orthogonal design strategy to study the effect of mesostructures on the mechanical behaviors of concretes and to determine the significance ranking of three significant factors consisting of coarse aggregate fraction, porosity, and mortar strength grade at three levels. Furthermore, by comparing the experimental and simulated results, it is verified that the simulation strategy is effective and can be directly used in practice to improve the security of concrete structures.

Discussion: Mechanical behaviour of different types of concrete under multiaxial compression

Discussion: Mechanical behaviour of different types of concrete under multiaxial compression

A damage plasticity model for different types of intact rock

A constitutive model for describing the nonlinear mechanical behavior of different types of intact rock subjected to complex 3D stress states is presented. It is formulated on the basis of a combination of plasticity theory and the theory of damage mechanics along the lines of a damage-plastic model for concrete. Irreversible deformations, associated with strain hardening and strain softening, as well as degradation of stiffness can be modeled. The material parameters and the model parameters are identified by means of an optimization procedure combining an evolutionary and gradient based optimization algorithm with niching strategy. The proposed model is validated by numerical simulations of laboratory experiments conducted on specimens of marble, granite and sandstone. The simulations are performed at integration point level. Thereby, the capability of capturing key features of the constitutive behavior of different types of intact rock is demonstrated. Finally, the application of the model to structural analyses is demonstrated by simulating a boundary value problem, including the formation of shear bands.

Tensile test and interface retention forces between wires and composites in lingual fixed retainers.

In daily orthodontic clinical practice retention is very important, and lingual retainers are part of this challenge. The failure of lingual retainers may be due to many factors. The aim of this study was to assess the retention forces and mechanical behavior of different types of wires matched with different kinds of composites in lingual retainers. A tensile test was performed on cylindrical composite test specimens bonded to orthodontic wires. The specimens were constructed using four different wires: a straight wire (Remanium .016×.022″ Dentaurum), two round twisted wires (Penta One .0215″ Masel, Gold Penta Twisted .0215″ Gold N'braces) and a rectangular braided wire (D-Rect .016×.022″ Ormco); and three composites: two micro-hybrids (Micro-Hybrid Enamel Plus HFO Micerium, and Micro-Hybrid SDR U Dentsply) and a micro-nano-filled composite (Micro-Nano-Filled Transbond LR 3M). The test was performed at a speed of 10mm/min on an Inström device. The wire was fixed with a clamp. The results showed that the bonding between wires and composites in lingual fixed retainers seemed to be lowest for rectangular smooth wires and increased in round twisted and rectangular twisted wires where the bonding was so strong that the maximum tension/bond strength was greater than the ultimate tensile strength of the wire. The highest values were in rectangular twisted wires. Concerning the composites, hybrid composites had the lowest interface bonding values and broke very quickly, while the nano- and micro-composites tolerated stronger forces and displayed higher bonding values. The best results were observed with the golden twisted wire and reached 21.46 MPa with the Transbond composite. With the rectangular braided wire the retention forces were so high that the Enamel Plus composite fractured when the load exceeded 154.6 N/MPa. When the same wire was combined with the Transbond LR either the wire or the composite broke when the force exceeded 240 N. The results of this study show that, when selecting a lingual retainer in daily clinical practice, not only must the patient's compliance and dependability be considered but also the mechanical properties and composition of different combinations of composites and wires.

Mechanical behavior of different types of concrete under multiaxial tension–compression

The strength of concrete under multiaxial tension–compression (biaxial tension–compression (T–C) and triaxial tension–compression–compression (T–C–C)) in the direction of tensile stress and compressive stress waslower than the uniaxial tensile strength and uniaxial compressive strength, respectively. This reduction is affected by many factors. Among these factors, type of concrete, method of friction-reducing in the direction of compressive load, stiffnessof testing machine and loading rate etc. are the main factors. The mechanical behavior of normal air-entrained concrete subjected to biaxial T–C, triaxial T–C–C was studied in this paper. The experimental results of normal air-entrained concrete under multiaxial tension–compression and mechanical behavior of other types of concrete under multiaxial tension–compression conducted in the same testing machine was comparedandanalyzed. The failure criterion of various types of concrete under biaxial T–C and triaxial T–C–C was proposed. It provides the experimental and theory foundations for strength analysis of various concrete structures.

Mechanical behaviour of different types of concrete under multiaxial compression

The strength of concrete under biaxial compression and triaxial compression is higher than the strength under uniaxial compression, but the level of increase is affected by factors such as the type of concrete, differences in testing machines, loading rate, etc. Based on this, an experimental investigation into the strength of normal air-entrained concrete (NAEC) under biaxial and triaxial compression loading conditions was carried out. The experimental results on NAEC were compared with the multiaxial compression strengths of other types of concrete obtained using the same testing machine. According to the test data, failure criteria and multiaxial ultimate strength envelopes in principal stress space were proposed. The test results indicated that biaxial compressive strength is higher than uniaxial compressive strength and the maximum increase of ultimate strength occurred at a biaxial compression stress ratio of 0·5 for all types of concrete. A relationship between biaxial compressive strength, triaxial compressive strength and stress ratio was developed. This work provides theoretical and experimental foundations for strength analysis of concrete structures.

Mechanical behavior of MoS2 nanotubes under compression, tension, and torsion from molecular dynamics simulations

The mechanical behavior of different types of single-walled and double-walled MoS2 nanotubes when subjected to external compressive, tensile, and torsional loading is investigated using classical molecular dynamics simulations. The forces on the atoms are determined using a reactive empirical bond-order potential parameterized for Mo-S systems. The simulations report on the elastic properties of the different MoS2 nanotube systems as well as the interrelationships between the buckling behavior and the structural parameters of the nanotubes, such as length, diameter, chirality, and number of walls. The simulations predict that the most important factor influencing mechanical response is the number of walls present and, to a lesser extent, the diameters of the nanotubes, with the other structural parameters predicted to have little effect on the results over the range investigated. These findings are consistent with reported density functional theory calculations and experimental data for WS2 and MoS2 nanotubes.

An Associative and Non-Associative Anisotropic Bounding Surface Model for Clay

An anisotropic elastoplastic bounding surface model with non-associative flow rule is developed for simulating the mechanical behavior of different types of clays. The non-associative flow rule allows for the simulation of not only strain-hardening but also strain-softening response. The theoretical framework of the model is given, followed by the verification of the model as applied to the experimental results of a strain-hardening Kaolin tested under different undrained stress paths. The undrained behavior of Boston Blue clay, which exhibits a strain-softening behavior, is also simulated. It is shown that the non-associative nature of the model gives more accurate results than those of the same model employing an associative flow rule, especially for normally consolidated Kaolin specimens. The results show that the model is also capable of simulating the strain-softening behavior of Boston blue clay with reasonable accuracy.

Nonlinear finite-element modeling of graphene and single- and multi-walled carbon nanotubes under axial tension

An effective finite-element (FE) approach for modeling the structure and the deformation of single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs) is presented. An individual tube was modeled using a frame-like structure with beam elements. The effect of van der Waals forces, crucial in MWCNTs, was modeled by spring elements. The success of this new carbon nanotube (CNT) modeling approach was verified by comparing the simulation results for single- and multi-walled nanotubes and graphene with other experimental and computational results available in the literature. Simulations of final deformed configurations were in excellent agreement with the atomistic models for various deformations. The proposed approach successfully predicts the experimentally observed values for mechanical behavior of SWCNTs and MWCNTs. The results demonstrated that the proposed FE technique could provide a valuable tool for studying the mechanical behavior of different types of nanotubes, as well as their effectiveness as load-bearing entities in nanocomposite materials.

Numerical simulation of steel pretensioned bolted end-plate connections of different types and details

This paper describes the development of a finite element numerical model with the ability to simulate and analyse the mechanical behaviour of different types of beam–column end-plate connections in which all of the bolts are pretensioned. The general purpose ANSYS software forms the basis of the modelling and its new functions are used to simulate the interface between the end plate and the column flange, as well as the pretension force in the bolts. Modelling of this kind has hitherto not been reported. The finite element model is compared with test results, which verify that the numerical procedure can simulate and analyse the overall and detailed behaviour of a number of types of bolt-pretensioned end-plate connections and components accurately, including the generation of the moment–rotation ( M – ϕ ) relationship, the contact status between the end-plate and the column flange, the behaviour of the end plate, the panel zone and bolts, and the influences of the bolt pretension force. Moreover, the numerical model also provides some additional useful results which are difficult to measure during testing, including the distribution of the pressure and frictional forces between the end plate and column flange induced by the bolt pretension and the moment at the joint, and the principal stress flow in the connections. This knowledge provides a basis for developing mechanical models consistent with the Eurocode component method of joint design. The validated numerical model is used for additional parametric finite element analyses of a number of beam-to-column bolt-pretensioned end-plate connections so as to produce a comprehensive study of their behaviour.

Material properties of concentrated pectin networks

We have examined the mechanical behaviour of different types of pectin at high concentrations (>30% w/w), relevant to the behaviour of pectin in the plant cell wall, and as a film-forming agent. Mechanical properties were examined as a function of counterion type (K +, Ca 2+, Mg 2+), concentration and extent of hydration. Hydration was controlled in an osmotic stress experiment where pectin films were exposed to concentrated polyethylene glycol [PEG] solutions of known osmotic pressure. We investigated the mechanical behaviour under simple extension. The results show that the swelling and stiffness of the films are strongly dependent on pectin source and ionic environment. At a fixed osmotic stress, both Ca 2+ or Mg 2+ counterions reduce swelling and increase the stiffness of the film.

Application of a Unified Viscoplastic Model With Mixed Hardening to Ionic Solids and Metallic Alloys

Abstract The mechanical behavior of different types of polycrystalline materials shows many common features in the ductile inelastic flow regime. It is typically controlled by dislocations motion, which involves the competitive action of hardening and recovery processes that induces a strong dependency upon mechanical history. The object of this paper is to show how a constitutive model, named SUVIC, can be used to describe and predict in a unified manner the inelastic response of various types of materials. For that purpose, the authors use laboratory test results obtained on alkali halides (NaCl) and on metallic alloys (Inconel 738LC and A508 steel) at different homologous temperatures.

Self-hot-melt joining of polymers to lacquered metal surfaces

Metal cans represent the dominant form of packaging in the food and beverage markets. Organic coatings i.e., lacquers, are applied to the inside of the cans to prevent undesirable interactions. The most common lacquer is based upon epoxy–phenolic materials. Advances in packaging technology have directed a requirement for the non-adhesive attachment of thermoplastic compounds, lids and fixtures such as gas capsules “Widgets” to the coatings of metal cans. This represents a new challenge and requires adaptation of the joining techniques currently available. This paper examines the joining of thermoplastic materials to epoxy–phenolic-lacquer-coated tin-free steel. A range of thermoplastics was characterised by their mechanical, thermal and surface energetic properties. A particular joining technique was then developed involving the simultaneous heating and pressing of the coated metal against the thermoplastic component. The process parameters of temperature, pressure and time were evaluated in terms of the properties of the bond. The mechanical behaviour of different types of peel joint was investigated, together with the influence of the moisture content of the thermoplastics.

Comparative study of measured attenuation with the Rayleigh region scattering theory

The study of ultrasonic attenuation by a non-destructive method has an important role in characterizing the mechanical behaviour of different types of materials. The values of sound absorption coefficient (attenuation) of sintered magnesium aluminosilicate glass powder at different frequencies have been measured by the pulse echo method and the data were fitted considering Rayleigh region scattering. Because the sample consists of two phases, one glass and the other ceramic (cordierite), the value of the scattering coefficient can be calculated from the theory by considering a two-phase medium and this value can be compared with that from the Rayleigh region scattering part. The two values of the scattering coefficient are in fair agreement.

Fluid mechanics of circulating fluidized beds

AbstractA fluid mechanical model of segregated vertical gas‐solids flow has been developed. Mass and force balances were set up with the aid of this model and, finally, a dimensionless state and pressure drop diagram was calculated. In this diagram, the pressure gradient caused by the solids transport is plotted in dimensionaless form versus the superficial gas velocity in the form of a particle Froude number. Parameter is the ratio of the solids volumetric flow rate at minimum fluidization to the gas volumetric flow rate. The state and pressure drop diagram is valid for a given gas‐solids system, i.e. for a given Archimedes number and given minimum fluidization porosity. The fluid mechanical behaviour of different types of circulating fluidized beds can be explained with the aid of the state and pressure drop diagram for segregated vertical gas‐solids flow. As an example, the operating behaviour of circulating fluidized bed with a syphon in the solids downcomer is discussed. Measurements of the circulating solids mass flow rates are compared with calculation results.