Raj Kumar Sahu

National Institute of Technology Raipur | NIT Raipur · Department of Mechanical Engineering

Dielectric elastomer (DE) is gaining importance for potential strategic and commercial application as actuators. This paper reports the experimental investigation on different mechanical phenomena at large deformation of a commercially available acrylic dielectric elastomer material, VHB 4910 (3M) which is widely used for dielectric elastomer actua...

This paper studies the effects of frequency, pre-strain and electrode types on the dielectric property of a commercially available and most widely used acrylic elastomer, VHB 4910. The acrylic VHB film is pre-stretched in biaxial directions with the help of an in-house developed biaxial stretching device. The stretched film has been sandwiched betw...

Dielectric elastomers (DEs) are gaining acceptance as potential actuator materials because of their exhibition of a large amount of deformation when stimulated by electrostatic forces. However, time-dependent behaviour such as creep and stress relaxation still pose a great challenge for the design, modelling and control of the DE-based actuators. I...

Understanding the tunable viscoelastic behavior of dielectric elastomers for artificial muscles is important to regulate the electromechanical actuation, response time, energy density, sensitivity, duty cycle, etc. However, the performance of elastomers is well known to be regulated by varieties of filler particles, crosslinkers and plasticizers, t...

Desired ratio of relative permittivity and elastic modulus limits the application of silicone rubbers as flexible electromechanical actuators. The relative permit-tivity can be improved by incorporating varieties of high-k (high dielectric constant) particles and polymer reagents as plasticizers and crosslinkers into elastomer matrix. The present w...

Desired ratio of high relative permittivity and low elastic modulus limits the application of silicon rubbers in various engineering fields as flexible electromechanical actuators. The relative permittivity can be improved by incorporating varieties of high-k particles and polymer reagents as plasticizers and crosslinkers into elastomer matrix. The...

Desired ratio of high relative permittivity and low elastic modulus limits the application of silicon rubbers in various engineering fields as flexible electromechanical actuators. The relative permittivity can be improved by incorporating varieties of high-k particles and polymer reagents as plasticizers and crosslinkers into elastomer matrix. The...

Progress in the design and modifications of dielectric elastomers has offered numerous effective techniques to improve their electrically induced actuation response. The actuation behaviour improves due to changes in electromechanical properties that eventually signifies the adjustments in the aspects of the structure of elastomer. This report aims...

In response to stringent environmental rules and rising public awareness, internal combustion (IC) engines have undergone fast improvement to reduce friction and wear in recent decades. Liner is a sacrificial engine component that protects and provides a smooth reciprocation surface to the engine block. High hardness aluminum alloys are used to pro...

Dielectric elastomers (DEs) belong to electro-active polymers having high stretchability, rapid response, high energy density, etc. which makes them suitable candidature for the fabrication of soft electromechanical devices. In real application properties of DEs deteriorates due to internal heating and thermal environment. In this work, to realize...

In order to encourage environment friendly manufacturing, dry machining is extensively explored and acknowledged. Consequently Functionally Graded Cemented Tungsten Carbide (FGCC) with solid lubricant was prepared by Spark Plasma Sintering at different heating rate and sintering temperature. The wear behavior of developed materials was explored by...

Recently, additive manufacturing has become popular among researchers and scientists due to its unique ability to produce complex parts. Hence, this chapter deals with the additive manufacturing of functionally graded materials. Design and modeling procedures have been succinctly elucidated. Brief descriptions of various types of additive manufactu...

The present need for lightweight, high-strength materials in advanced applications has prompted researchers to concentrate on hybrid aluminium matrix composites (HAMCs). For automotive applications, boron carbide (B4C) and fly ash (FA)-reinforced HAMCs are viable options. Mechanical characterization of stir-casted B4C and FA-reinforced Al7075 HAMCs...

The effects of solid fillers on optical, electrical, mechanical, and electromechanical actuation behavior of VHB 4910 elastomer is inadequate, possibly due to readiness as a foam tape that makes the filler reinforcement a challenging work. VHB 4910 is modified by filling graphene oxide (GO) particles to realize the influences on material behavior t...

Aluminum alloy with SiC particles reinforcement, functionally graded composite cylinder is developed via horizontal centrifugal casting technique. Cylindrical specimen is fabricated with 8 wt% of SiC particles reinforcement in A356 under mould rotational speed of 800 rpm. The comparative hardness at different locations on the cylinder is measured b...

Microsphere based consecutive model is useful tool to predict the material behavior of dielectric elastomer composite containing directionally arranged soft fillers. Dielectric elastomers (DEs) belong to electroactive polymers (EAPs) family, which produce mechanical deformation in response to change in external electrical potential and vice-versa....

Lightweight and high-wear performance materials are currently in demand for various advanced applications in areas such as aerospace and automobiles. These demands can be achieved by hybrid aluminum matrix composites (HAMCs), as they possess excellent mechanical and tribological properties which can be customized using more than one reinforcement....

The functionally graded cemented tungsten carbide (FGCC) is a suitable material choice for cutting tool applications due to balanced hardness and fracture toughness. The presence of cobalt and CaF2 composition gradient in FGCC may enhance mechanical as well as antifriction properties. Therefore, structural design of self-lubricating FGCC was propos...

This article, exemplify the deformation behaviour of dielectric elastomer peristaltic actuator with variation in relative permittivity as a function of voltage induced strain. Modified model is proposed to predict the behaviour of peristaltic actuators, best suited for biomedical applications to transport incompressible fluids. Transportation is ac...

Dielectric elastomers are the potential material to configure soft electromechanical actuators and similar modules. But, understanding the relationship between molecular structures and properties of such elastomers in real-time is a powerful and lacking tool, important to consider when properties are targeted to improve by tailoring (macro)molecula...

Stir-casting is the appropriate and economical technique for HAMCs synthesis as it produces uniformly reinforcement distributed composite retaining finer grains. In the present work, Al 7075/x%wt.B4C/2% wt. fly-ash HAMCs were fabricated via stir casting route, where x is weight percentage of boron carbide (x = 2, 4, 6 and 8 wt%). Incorporation and...

Functionally graded materials (FGM) are advantageous due to its inherent composition gradient, results in tunable characteristics over defined length and fulfill the application requirement. The Sigmoid Functionally graded materials (SFGM) offer advantage in terms of reduction in stresses concentration at the interfaces. The thermal residual stress...

Modern-day industries are showing enormous attention towards green and clean manufacturing; subsequently, research on self-lubricating cutting tool material is in vogue. To deal with the incompatibility between the tribological and mechanical properties of monolithic self-lubricating cemented tungsten carbide, a functionally graded cemented tungste...

Interpenetration of dielectric elastomers with fillers is an effective technique to improve requisite properties for voltage induced electromechanical performance. However, the requirement that the rigid frame has to maintain its pre-strained state, and time/temperature related phenomenon like stress relaxation/concentration, strain-induced crystal...

This work reports the dependence of Raman spectra for unstrained, uniaxially and equi-biaxially pre-strained VHB 4910 dielectric elastomer. Typical band analysis techniques are used to determine the effect of strain on molecular structure. Distinct increase and decrease in fitted width of 2922 cm⁻¹ band is observed for uniaxial and biaxial strained...

Aluminum matrix composites (AMCs) and hybrid aluminum matrix composites (HAMCs) becomes choice for automobile and aerospace industries due to its tunable mechanical properties such as very high strength to weight ratio, superior wear resistance, greater stiffness, better fatigue resistance, controlled co-efficient of thermal expansion and good stab...

A comprehensive microstructural characterization is needed for complete understanding while formation of different phases during processing of any material. To establish a relationship between microstructure and mechanical properties precise and accurate microstructural characterization has been carried out. The characterization is done using optic...

This paper presents the results of theoretical study designed to measure the suitability of a dielectric elastomer as an actuator, from a group of acrylic and silicone elastomers. The micro molecular parameters of elastomers such as monomer type, monomer chain length and density were taken into consideration for analysis of actuation properties. Id...

Functionally graded cemented tungsten carbide belongs to a hybrid Functionally Graded Materials family. However synthesis of functionally graded cemented tungsten carbide is a great challenge due to possibility of “Co migration” and CaF2 vaporization during liquid phase sintering. Hence the present work deals with the development of nanocrystalline...

Measurement of the surface residual stress in a flat hot rolled steel strip using strain gauge method is considered in this paper. Residual stresses arise in the flat strips when the shear cut and laser cut is applied. Bending, twisting, central buckled and edge waviness is the common defects occur during the cutting and uncoiling process. These de...

Hybrid aluminum matrix composites (HAMCs) are capable to meet recent demands of advanced engineering applications due to its tunable mechanical properties and lower cost. Stir casting is one of the prominent and economical method for processing of continuous reinforced HAMCs. In this method, flow pattern is the key factor for distribution of partic...

Accurate and precise attempts were taken to study the affect of important machining variables on performance characteristics in turning of AISI H13 using ceramic tool. A three dimensional machining model using DEFORM 3D, a FEM based software were used for predicting the cutting forces, temperature etc by Langrangian model. The results obtained from...

Functionally graded materials (FGMs) are engineered materials that are inhomogeneous and can be purposefully processed to obtain discrete or continuously varying compositions/microstructures over a definable geometrical length. FGMs can be used in a number of applications, such as aircrafts, combustion nozzles, gas turbines, energy conversion cells...

In this paper, Maxwell stress of circular planar actuator at different applied voltages was estimated and then validated with the uniaxial compression test of three different dielectric elastomers (VHB, silicone and natural rubber). Pelrine’s equation was revisited to estimate Maxwell stress which causes the actuation in the planar direction. More...

This paper reports experimental characterisation of a dielectric elastomer which is used as a base material for electro-active polymer actuators and sensors. Specific deformation energy has been experimentally determined to characterise a dielectric acrylic elastomer for large elastic deformation. Specific deformation energy value was estimated fro...

This paper experimentally studied the large nonlinear deformation of VHB 4910 elastomer by uniaxial tests. The study reveals that the monotonic tensile stress-strain, hysteresis, cyclic stress softening and multistep stress relaxation of this elastomer exhibit rate-sensitivity. Toughness, failure stress, failure strain are shown to vary with strain...

Dielectric elastomer actuator (DEA) is a kind of soft actuators that can produce significantly large electric-field induced actuation strain and may be a basic unit of artificial muscles and robotic elements. Understanding strain development on a pre-stretched sample at different regimes of electrical field is essential for potential applications....

In this work, a new visco-hyperelastic constitutive model is proposed to describe the rate-dependent large deformation behaviour of an acrylic elastomer. The proposed model is based on the Zener model, which consists of a hyperelastic equilibrium spring and a Maxwell element to capture rate-dependent material response. The constitutive equation is...

A biaxial stretching device for simultaneous stretching of an elastomer sample, in both directions has been developed. The device comprises of a square bottom structure, a plurality of supporting rods connected vertically to a base member of the frame; at least four sliding bars with grip on each open end supported on an upper frame having rollers...

Elastomers have low elastic modulus, high specific energy density, light weight, high dielectric constant and high electrical breakdown strength. Due to these properties, elastomers are currently recognized as the future materials for actuator technology and actuators based on these materials are known as dielectric elastomer actuators (DEA). Based...

This paper reports the experimental study on the frequency and stretch dependency of permittivity of a commercially available acrylic dielectric elastomer (VHB 4910) film. The procedure for preparing samples with different thickness using in-house developed uniaxially stretching device is described. Copper tapes are implanted on two opposite sides...

The paper gives an overview of mechanical properties and forming behavior of dual phase steel sheet (DP 590). DP-590 has gained acceptance as automotive structural material as it combines high tensile strength with good formability. Forming limit diagram of DP-590 steel sheet has been constructed at the static loading condition. The forming limit d...