The automation of the land excavation machines can find applications in the excavation of soil in both terrestrial and planetary mining and construction. In the process of automating an earthmoving machine, we have utilized a model of soil-tool interaction that predicts resistive forces experienced at the tool during digging. The predicted forces can be used to model the closed loop behavior of a controller that serves the joints of the excavator so as to fill the bucket. Accurately predicting the excavation force that will be encountered by digging tools on the soil surface is a crucial part of designing of mini hydraulic excavator. Based on principles of soil mechanics, this paper focuses on application of an analytical model that is relatively simple and easy to determine required resistive force. Here, soil parameters like soil cohesions, soil density and soil surcharge etc. that can be determined by traditional soil strength tests and taken as reference. The excavation force is investigated and it is helpful in designing of the components of kinematic linkages. This paper emphasize on graphical representation of the relations between excavation force and different parameters like soil density, soil blade friction angle, soil cohesion, internal friction angle and depth of tool. This paper evaluates the digging force based on fixed bucket size of 300 mm length × 300 mm width × 300 mm depth and the minimum digging depth up to 1.5 m especially designed for construction applications.

Abstract-Excavators are used primarily to excavate below the natural surface of the ground on which the machine rests and load it into trucks or tractor. Due to severe working conditions, excavator parts are subjected to high loads. The excavator mechanism must work reliably under unpredictable working conditions. Thus it is very much necessary for the designers to provide not only a equipment of maximum reliability but also of minimum weight and cost, keeping design safe under all loading conditions. It can be concluded that, force analysis and strength analysis is an important step in the design of excavator parts. Finite Element Analysis (FEA) is the most powerful technique in strength calculations of the structures working under known load and boundary conditions. In general, computer aided drawing model of the parts to be analyzed must be prepared prior to the FEA. It is also possible to reduce the weight of the mechanism by performing optimization task in FEA. This paper provides the platform to understand the Modeling, FEA and optimization of backhoe excavator attachment, which was already carried out by other researchers for their related applications and it can be helpful for development of new excavator attachment.

The stress concentration factor is one of the most significant factors in design engineering in the modern era with lots of objectives across the world. Stress concentration is the localization of high stresses primarily due to discontinuities within the time, abrupt changes in cross-section, and contact with stresses. This paper focuses on a problem with different discontinuities as specially holes present in a plate like isotropic, anisotropic and orthotropic etc. The different methods used by various authors to evaluate stress concentration with different related parameters, and describe the study related to the results carried out by them. Finite plate with polygonal, circular, inclined circular, and elliptical types holes has been considered one of the most important design applications in the present era. In the present work, the analysis and reviews are based on the following (a) types of discontinuities, (b) types of loading, (c) material/Composites/Plies (d) orientation of discontinuities in a finite plate. Finally, the scope of this research work is incorporated.

Differential longitudinal thermal expansion between the shell and the tube bundle is a well-known problem in fixed tubesheet heat exchanger design. An expansion bellows provide flexibility for thermal expansion and also function as a pressure retaining part. In this paper, guidelines for design of flanged and flued type (thick wall) expansion bellows available in international codes and standards including ASME VIII-1 and 2, EN-13445, and TEMA and EJMA codes are presented. These codes and standards are compared in terms of information available for thick wall expansion bellows design with regard to condition of applicability of design formula, spring rate determination, parameter to define the initial geometry, stress determination, and fatigue evaluation. Inherent limitations of these codes with respect to expansion bellows design, research gape, and recommendations for effective design are also presented in this paper. Brief history and information provided in various codes and standards related to unreinforced thin wall expansion bellows (bellows expansion joints) are also presented to understand evaluation of expansion bellows design.

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Backhoe excavators are construction machines can be use for hazardous and even poisonous environmental conditions, worst working conditions, severe weather, and dirty areas where it is very difficult to operate machine by human operator. The excavation task can be performing successfully and effectively for above mentioned working conditions by semiautonomous or fully computer controlled of excavation machines. For this it is important to understand the kinematics of this machine. For autonomous excavation operation of a backhoe, it is desirable to place the bucket to a specified location. The bucket configuration can be determined by the direct kinematic equations for given lengths of the piston rods in the actuators or the joint angles. This paper emphasize on the explicit expressions for the direct (forward) kinematics of backhoe excavator. It covers systematic procedure to assign Cartesian coordinate frames for the links (joints) of an excavator. The developed forward kinematic model is intended for development of an automated excavation control system for light duty construction work and can be applied for heavy duty or all types of backhoe excavators.

Flanged and flued type expansion joint (thick wall expansion bellow) used as an integral part of many shell and tube heat exchanger where process conditions produce differential expansion between shell and tubes. It provides flexibility for thermal expansion and also functions as a pressure retaining part. Design of expansion joints is usually based on trial and error method in which initial geometry must be assumed, and accordingly maximum stresses and spring rate are be calculated. Inadequate selection of geometry leads to higher tubesheet and bellow thickness, which increases cost of equipment. This paper presents standardization and optimum design approach of flange and flued expansion bellow fulfilling ASME VIII-1 and TEMA standard requirement. Methodology to define expansion bellow geometry is developed, and geometry dimensions are tabulated for expansion bellow diameter from 300 to 2000 mm and thickness from 6 to 30 mm. Each defined geometry is analyzed using finite element method, and maximum von Mises stresses are calculated for bellow axial displacement from 0.5 to 1.5 mm and internal pressure from 0.1 to 6.5 MPa. Spring rate is also calculated for each defined geometry for consideration in tubesheet calculation. Accordingly, optimum design methodology is developed, tested, and compared with existing design. Results depicted that proposed standardization approach and design methodology will optimize expansion bellow and tubesheet thickness and will also save considerable time in finalization of heat exchanger design.

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