Brownian dynamics investigation of the Boltzmann superposition principle for orthogonal superposition rheology

Metri, Vishal; Briels, Willem J.

doi:10.1063/1.5080333

Cited by 13 publications

(5 citation statements)

References 52 publications

(75 reference statements)

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“…As the applied load intensity increases, the percentage difference between traction and compression displacement increases, and as the load speed increases, they increase. Based on the Boltzmann superposition principle, which describes the response of a material to different loading histories and fitting the deformations peaks for each cycle [ 21 , 22 ], in Figure 5 a–f are graphically represented the master curves covering the accumulated peak deformations in tensile ( Figure 5 a,c,e) and compression tests ( Figure 5 b,d,f). The behavior of the tested specimens differs in the two types of axial stresses.…”

Section: Resultsmentioning

confidence: 99%

Degradation of Mechanical Properties of Pine Wood Under Symmetric Axial Cyclic Loading Parallel to Grain

2020

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The mechanical properties of wood, respectively the elastic, plastic, and strength properties, depend on a large number of factors, due both to its structural and physical characteristics, as well as to the size, direction, nature, and speed of application of forces. Wood, generally considered to be a viscous-elastic material, has creep deformations over time under the effect of a constant load. In this study the behavior of pine wood samples was investigated due to its large utilization in different finished products, such as roof construction, furniture, outdoor applications, garden furniture, and toys. The paper aims to analyze the viscoelastic behavior of pine wood subjected to cyclically loading to traction-compression with different loads (1 kN; 1.5 kN; 2 kN), applied at different speeds (1 mm/min; 10 mm/min). It was observed that, at low speeds (1 mm/min) and low intensities of the applied force, it was possible to distinguish the three creep regions specific to wood: the primary area (primary flow), the secondary area, and finally the tertiary creep. As the force increases, the law of variation of the wood flow changes. The degradation of longitudinal elasticity modulus occurs with the increase of the number of cycles, so after 20 alternating symmetrical cycles of traction-compression of the pine wood samples, there is a decrease of its values by 35%.

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Section: Resultsmentioning

confidence: 99%

Degradation of Mechanical Properties of Pine Wood Under Symmetric Axial Cyclic Loading Parallel to Grain

2020

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“…The long-term strength of rock and soil is an important parameter for assessing the stability of landslides [49,50]. At present, the main methods to obtain long-term strength through creep test curves include the isochronous curve method [3,51], which uses the creep test curve and the Boltzmann superposition principle [52] and states that the stress response of a system to a time dependent shearing deformation may be written as the sum of responses to a sequence of step strain perturbations in the past [53], to obtain the stress-strain isochronous curves corresponding to the different deviatoric stress at the same time [54]. Figure 10a-e show the isochronous curves corresponding to the creep curves of the samples after five kinds of dry-wet cycles (n = 0, 5,10,15,20).…”

Section: The Long-term Strength Of Loess Samples With Different Dry-w...mentioning

confidence: 99%

Time-Dependence of the Mechanical Behavior of Loess after Dry-Wet Cycles

Liu

Wang

et al. 2022

Applied Sciences

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The structure, time-dependent mechanical deformation, and strength characteristics of loess, which is loose and porous with well-developed vertical joints, are greatly affected by the dry-wet cycles, which are attributed to periodic artificial irrigation, rainfall, and water evaporation. To better understand the creep characteristics of loess under the effect of dry-wet cycles, Q2 loess samples obtained from the South Jingyang County, China, were subjected to different dry-wet cycles (0, 5, 10, 15, 20) and sheared in triaxial creep tests. The experimental results revealed that: firstly, the maximum value of the deviatoric stress corresponding to creep failure gradually decreases with an increase in the dry-wet cycles. Secondly, the long-term strength of the loess after dry-wet cycles were obtained through the Isochronous Curve Method. It is found that the long-term strength and the number of dry-wet cycles showed an exponential decreasing relationship. In addition, the creep damage mechanism of loess due to dry-wet cycles is proposed. This study may provide the basis for understanding the mechanical behavior of the loess under the effect of dry-wet cycles, as well as guidelines for the prevention and prediction of loess landslide stability.

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“…Establishing a model that has a time response that is consistent with or close to that of polymers is most important for solving the viscoelastic problem of polymers such as rubber. Commonly used models include the generalized Maxwell model, generalized Kelvin model, standard linear solid model, and standard linear three-parameter model [28][29]. In this study, the generalized Maxwell model was selected as the viscoelastic model, as shown in Figure4.…”

Section: Viscoelastic Model Modelingmentioning

confidence: 99%

Design and Dynamic Modeling of a Coupled-Drive Flexible Joint for Nursing-Care Robot Arm

Guo

Yang

et al. 2022

Preprint

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Patient transfer is one of the most physically challenging tasks in nursing care, the burden of which can be reduced by introducing nursing-care robots. This study proposes a coupled-drive 2-DOF (degree of freedom) joint for nursing-care robot arms to ensure that the arms have a high load capacity and smooth configuration, which is crucial for safe and comfortable contact with the care receiver. This paper presents the design methodology of the coupled-drive joint by using differential mechanism which can superimposing the torque of two motors to achieve a high load capacity. To make the joint flexible for this purpose, we introduced rubber layers in the connections of the major parts. We expressed the dynamics of the rubber layers using a hyper-viscoelastic model and applied it to the joint dynamics to build a dynamic model of the coupled-drive 2-DOF joint using the Lagrange method. To demonstrate the effectiveness of the arms with coupled-drive joints in patient transfer tasks, we built two arms, integrated them into a robot, and conducted a transfer experiment in which the motions were planned based on the dynamic model. The results showed that the designed joints had both a high load capacity and flexibility for safe and comfortable contact with humans.

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Brownian dynamics investigation of the Boltzmann superposition principle for orthogonal superposition rheology

Cited by 13 publications

References 52 publications

Degradation of Mechanical Properties of Pine Wood Under Symmetric Axial Cyclic Loading Parallel to Grain

Degradation of Mechanical Properties of Pine Wood Under Symmetric Axial Cyclic Loading Parallel to Grain

Time-Dependence of the Mechanical Behavior of Loess after Dry-Wet Cycles

Design and Dynamic Modeling of a Coupled-Drive Flexible Joint for Nursing-Care Robot Arm

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