China
Africa
Explore chapters and articles related to this topic
Structure-Property Relationships for the Mechanical Behavior of Rubber-Graphene Nanocomposites
Published in Titash Mondal, Anil K. Bhowmick, Graphene-Rubber Nanocomposites, 2023
Research interest has grown exponentially in the recent past in nanocomposites made from rubber and graphene. A host of studies have shown that the addition of graphene notably enhances the mechanical properties of rubber, including the strength, stiffness, and deformation at failure. Here, stiffness refers to resistance to deformation, strength refers to maximum load bearing capacity before failure, and toughness refers to energy dissipation capacity by failure. So, in this sense, the toughness is also indicative of the maximum deformation capability before failure. In this section, we will review the main findings. The reader is also referred to other excellent review articles on this topic (Wang et al. 2017, Stöckelhuber et al. 2017, Mondal et al. 2016, Papageorgiou et al. 2015, Liu et al. 2018, Srivastava and Mishra 2018, Bokozba 2019, Zhang et al. 2019, Mensah et al. 2018, and Bhavitha et al. 2021).
An Introduction to Material Selection
Published in Keith L. Richards, The Engineering Design Primer, 2020
Stiffness is the ability of a material to maintain its shape when subject to a load or force. Consider Hooke's law, where a test material is incrementally loaded to produce an extension which is plotted against the load, and the resultant slope is used to demonstrate the relationship between stress and strain. Within the linear range of the extension, the material will return to its original size when the load or force is removed. If the test material is loaded so that this linear extension is reached, the material is said to have reached its ‘proportional limit’; any further extension past this limit will then result in the test material not returning back to its original size when the applied load or force is removed. This phase is called ‘the non-proportional limit’.
A constitutive model for rubbers providing temperature dependent behavior and self-heating
Published in Bertrand Huneau, Jean-Benoit Le Cam, Yann Marco, Erwan Verron, Constitutive Models for Rubber XI, 2019
The simulative prediction of rubber behavior demands material models including many effects, such as strain-induced softening (Mullins-effect) as well as amplitude and frequency dependence of the dynamic moduli. In addition, the application temperature has a strong impact on the resulting material behavior. Rey et al. (2013) point out, that unfilled rubber has a unique property resulting from the en- tropic elastic nature of elastomers. Increased temperature results in increased material stiffness. Despite that, technical compounds show trends that seem contradictory. The industrial material investigated in this contribution, which is a NR-compound filled with carbon black, shows strong temperature dependence regarding properties like softening and hysteresis while the overall stress level is rather stable. Further, the thermal state of a rubber part changes necessarily on mechanical deformation. There is a reversible temperature change due to the kinetic nature of rubber elasticity, often denoted as entropy elasticity, as well as a irreversible heat build-up due to dissipative effects on cyclic loading. Simulation of all these effects requires the solution of a thermomechanically coupled problem.
Bending properties of carbon fiber reinforced composite multilayer damping structures with different types of stiffeners
Published in Mechanics of Advanced Materials and Structures, 2023
Shaoqing Wang, Jianmin Su, Shuo Li, Anfu Guo, Peng Qu, Zhilin Zhai
From Figure 5(a), it can be observed that when the stiffener height was 0 mm, the structure with a larger elastic modulus ratio had a greater rigidity, and under the same uniform load, the SCD was smaller. As the stiffener height increased, the bending section modulus of the structure increased, and the overall stiffness of the structure improved. So, under the action of uniform load, the structural central deflection decreased. When the height of the stiffeners is smaller than the length of the stiffener, with the increase of the height of the stiffeners, the rate of decrease of the central deflection becomes faster. It is because of the fact that the positive correlation between the moments of inertia of the stiffener and the higher power of the stiffener height makes the growth rate of the moment of inertia higher than that of the stiffener height. When the stiffener height was large enough, the center deflection difference of stiffened plates with different elastic modulus ratios became relatively small.
Nonlinear dynamic instability of laminated composite stiffened plates subjected to in-plane pulsating loading
Published in Mechanics of Advanced Materials and Structures, 2023
Danish Fayaz, S. N. Patel, Rajesh Kumar, Gaurav Watts
It is observed from Figure 13a that with the increase in the number of layers, the amplitude at central point of the stiffened plates decreases. However, at point A1 it is observed that with the increase in time, the amplitude of the stiffened plates become unbounded with respect linear solution, while the amplitude of the vibration of the stiffened plates becomes gradually steady with respect nonlinear theory as shown in Figure 13b. When the loading frequency falls outside the dynamic instability zone (point B1), both the linear and nonlinear responses are similar, stable, and bounded as shown in Figure 14a, b. Increasing the number of layers in the stiffener can lead to an increase in the overall stiffness and strength of the structure, which can affect its time history response and improve the overall load-carrying capacity of the structure. The amplitude of the vibrations decreases with an increase in the number of layers which can be seen in both linear and nonlinear responses of the system.
Health assessment based on dynamic characteristics of reinforced concrete beam using realtime wireless structural health monitoring sensor
Published in Journal of Structural Integrity and Maintenance, 2020
Aamar Danish, Faran Tayyab, Muhammad Usama Salim
The beam testing was divided into four stages: (i) undamaged, (ii) appearance of 1st crack, (iii) implementation of 80% load and (iv) beam fully crack. Wired and wireless accelerometers gave the response to each mentioned stage as shown in Figure 6. In the first stage, the acceleration due to vibrations induced in the structure first increases but it becomes constant with time. During stage 2 and stage 3, the damage was started in the beam and the acceleration initially increases but then decreases as compared to that of stage 1 with fluctuating acceleration. When the beam has fully damaged the acceleration produced due to vibration in the structure shows considerable change in the acceleration. In this stage, acceleration decreases a lot as compared to stage 1. As the frequency is directly related to stiffness which means decrease in frequency results in decrement of structure’s stiffness. In view of this, the acceleration response graph was converted into frequency domain for each stage using Fast Fourier Transform (FFT) as shown in Figure 7.