In any structure or structural element before application in actual field there is some testing should have to perform so that to check its reliability and serviceability. So in characterization process we have to set its limitation either they are structural or geometrical. At some extent, in beginning of service life of any structure main aim of SHM is also that to characterize the limiting values only. Latter it defines rest of life and current performance of structure.
The Structural health monitoring can be defined as non-destructive in-situ structural evaluation method in which several types of sensors and actuators are attached or embedded in structure. Structural Health Monitoring (SHM) aims to give, at every moment during the life of a structure, a diagnosis of the “state” of the constituent materials, of the different parts, and of the full assembly of these parts constituting the structure as a whole. The state of the structure must remain in the domain specified in the design, although this can be altered by normal aging due to usage, by the action of the environment, and by accidental events.
And the rest part is Prognosis in which the prediction of residual life of the structure is to be done. Due to time-dimension of monitoring, which makes it possible to consider the full history database of the structure, and with the help of Usage
Monitoring, it can be able to provide a prognosis (evolution of damage, residual life, etc.).
In structural health monitoring damage is defined as changes to the material and/or mechanical properties of a structure, including changes to the boundary conditions, which adversely affect the structural performance. These sensors collect data which is analyzed and stored for future analysis and reference that can be used for safety, integrity, strength or performance.
Components of SHM
• The structure on which the SHM system will be placed.
• Sensors and Actuators
• Acquisition system
• Communication of information
• Intelligent processing and analyzing of data
• Storage of processed data
• Damage modeling and damage detection algorithms
• Retrieval of information as required
• Layout of structural health monitoring
Fig.1.1 Layout of structural health monitoring
TABLE 1.1 Categories of SHM
S.no S.no. Categories description
Static Field Testing Behavior tests
Dynamic Field Testing Stress history tests
Ambient vibration tests
Dyn. Load Allowance (DLA) tests .
Pullback (anchored cables) tests
Continuous Monitoring Active monitoring
4 Periodic Monitoring Field testing Tests to determine changes in structure
Advantages of SHM
• Increased understanding g of in‐situ structural behavior
• Early damage detection
• Assurances of structural strength and serviceability
• Decreased down time for inspection and repair
• Development of rational maintenance / management strategies
• Increased effectiveness in allocation of scarce resources
• Enables and encourages use of new and innovative materials
Levels of SHM
• Level I: This basic level SHM system is capable of detecting damage in a structure, but cannot provide any information on the nature, location or severity of the damage .it cannot assess the safety of the structure.
• Level II: Slightly more sophisticated than level 1 SHM system level II system can detect presence of damage and can also provide information about its location. So that can be detect and repair
• Level III: In this level we can locate pin point location and of damage and its severity
• Level IV: It is the most sophisticated system of SHM and provide detailed information about presence, location and severity of damage and in some extent it can also provide information about the life of the structure.
1.3 What is loading frame
A high stiffness support structure against which the test forces can react. The load frame comprises a base beam, two columns, and a moving crosshead. It is a self-straining structure that means no other load is transfers to ground except its self-weight.
Fig.1.2 loading frame
Types of loading frame
• According to axis of loading
o Vertical loading frame
Fig.1.3 Vertical loading frame
o Horizontal loading frame
Fig.1.4 Horizontal loading frame
• Other types
o Straight Sided four column Type
o Straight Sided box Type
o Straight Sided Column/C-Frame Type,
o H-frame Type,
Significance of loading frame
• The test-loading frame can be utilized to test the behavior and load-carrying capacity of both full-size structures as well as separate structural member.
• This equipment is best suited for producing static and repeated loadings
1.4 Objectives of the study
Characterization of loading frame
to monitor health of loading frame.
vertical stiffness means stiffness of structural member in vertical loadings
displacements under characteristics load etc
And comparative study of the general manual results with experimental results.
1.5 Outline of project
Is to study various aspects of structural health monitoring and part of instrumentation involved in it.
Experimental procedure setup and methodology used.
Description of experimental investigation.
Description of strain gauges and their types.
Comparative study of experimental and theoretical results.
1.6 Scope of the work
To achieve the above objective, to the scope of this work for the project generally involves the following.
To verify the loading frame geometrically by performing flatness test and parallelism tests.
To verify structural performance of frame using strain gauges LVDT’s, data logger and load cell as instrumentation part and hydraulic jack spacers as mechanical part.
To apply the tests more times to verify reliability of our instrumentation system.
To make completive study of results of theoretical and experimental calculation and prediction about health of frame.
I.C. Medland , (1966).
• Collapse load of steel frame works allowing for the effect of strain hardening
Concerned an investigation of the behavior of structures composed of the high yield-stress steel to B.S. 968. Moreover, it concern about the applicability of the plastic theory to the design of such type of framed structures. In this investigation, he had conducted a number of bending tests on simply supported beams of having I-sections in the new steel to check the applicability of the previous theories to the estimation of the strain-hardening characteristic of such beams. He had found that the rigid-plastic-strain-hardening (r.p.s.h.) and rigid-plastic-rigid (r.p.r.1 theories both gave good estimates of the strain-hardening characteristic of high tensile steel beams and that the basic r.p.r. theory could be used as a suitable basis for a design method.
• Computer aided design of hydraulic press by and
The study was concerned about CAD (computer-aided design) of hydraulic press structure of capacity 918KN in which they used finite element model to analyze the press because only through FEM method we can reach near about to model exact shape like its topology. They also considered factors such as fillet, edge cutting, provision of openings, change in position of stiffeners and eccentric loading. They explained us merits of FEM for modeling of such types of complicated structure. On the basis of this Investigation, certain significant guidelines related to its behavior and it’s design have been obtained for the analysis& design in future of press frames that are.
(i) Clearance between members should be minimum, as much as accuracy expected from the machine tool;
(ii) Proper alignment of different elements, especially for sliding ones should be ensured with greater accuracy.
Dr. Mohamad M. Salehet.al, ( 1992)
• Design study of heavy duty hydraulic machine using FEM technique,
This thesis describes the systematic procedure for investigating the structural performance and the design and analysis of the welded structure of a 150-tonne hydraulic press machine in other sense load frame or load carrying structure . This machine was designed without any measurement earlier. The author has discussed the theoretical and experimental model of the machine structure to make the accurate and optimal design analysis for further development in the present machine design at minimum time and at lower cost. The applicability of the existing Computer based Finite Element package, as a CAD (computer aided design) tool, was also discovered. They use both conventional analytical formula and numerical technique, using Finite Element to model it theoretically. But the conventional model is based on the simple bending theory in which they use the total strain energy principle for 2D beams or frames. The LUSAS Finite Element software is used for numerical modeling because modeling and solving the equation of FEM f such type of complex structure is too problematic or can say impossible and why they waste their labor while facilities are. By using FE model they able to be consider such factors which are not possible to replicate by other method. The they factors considered are:- the boundary condition the mesh density and the type of the element being used. The experimental model consist of load cells strain gages and L.V.D.T. and A comparison has been made between the experimental and theoretical results.
L.A. Bisby 2004
• An Introduction to structural health monitoring, L.A. Bisby 2004
Concerned about the introduction to structural health monitoring and its various aspects like its components, classification, levels, methods of computation etc.also gives a brief description of sensors and actuators and there types with some example of bridge structure.
Charles R. Farrar et.al,(2006)
An Introduction to structural health monitoring,
The study is concerned about an introductory part about SHM that The process of implementing a damage identification strategy for aerospace, civil and mechanical engineering infrastructure is referred to as structural health monitoring (SHM). damage is defined as changes to the material and/or geometric properties of these systems, including changes to the boundary conditions and system connectivity, which adversely affect the system’s performance. it also concerned about wide variety of highly effective local Non-destructive evaluation tools are available for such monitoring and also tells about motivation for SHM technology development, feature extraction and information condensation, Operational evaluation and Challenges for SHM.
Mohammad Osman et al (2011)
• Finite element analysis of beam-column joints in steel frames under cyclic loading.
This study is concerned to develop simple and accurate three-dimensional (3D) finite
element model (FE) capable of predicting the actual behavior of beam-to-column joints in steel frames subjected to lateral loads. The software package ANSYS is used to model the joint. The bolted extended-end-plate connection was chosen as an important type of beam–column joints. The extended-end-plate connection is chosen for its complexity in the analysis and behavior due to the number of connection components and their inheritable non-linear behavior. Two experimental tests in the literature were chosen to verify the finite element model. The results of both the experimental and the proposed finite element were compared. One of these tests was monotonically loaded, whereas the second was cyclically loaded. The finite element model is improved to enhance the defects of the finite element model used. These defects are; the long time need for the analysis and the inability of the contact element type to follow the behavior of moment–rotation curve under cyclic loading. As a contact element, the surface-to-surface element is used instead of node-to-node element to enhance the model. The FE results show good correlation with the experimental one. An attempt to improve a new technique for modeling bolts is conducted. And Concluded that FE results and the experimental results are compared to examine the validity and the predictability of the proposed model. The FE results have good agreement with the experimental one at different stages of loading. The FE model can provide a variety of results at any location within the model. A viewing of the full fields of stresses and strains are possible in the FE model. This provides a great advantage in monitoring the components of the connection. And shown that modeling a beam-to-column connection loaded cyclically is expensive and time consuming in both building and solving the model. So, there is a great need to model the connection more simply and at the same time with an acceptable accuracy. and gave a proposal for a new technique of modeling bolts is presented. The proposal is to model the bolts as a mixing of shell elements (for head and nut) and link elements (for shank). This technique for modeling of bolts, called shell bolt, was examined and compared to other methods for modeling of bolts and was found to be accurate. Also, it needs less time of solution and less storage volume comparing with other techniques for modeling the bolts.
Philip Rinn et al (2012)
• Stochastic method for in situ damage analysis,
study is concerned about physics of stochastic processes we present a new approach for structural health monitoring. this new method allows for an in-situ analysis of the elastic features of a mechanical structure even for realistic excitations with correlated noise as it appears in real world situations. In particular an experimental set-up of undamaged and damaged beam structures was exposed to a noisy excitation under turbulent wind conditions. The method of reconstructing stochastic equations from measured data has been extended to realistic noisy excitations like those given here. In our analysis the deterministic part is separated from the stochastic dynamics of the system and we show that the slope of the deterministic part, which is linked to mechanical features of the material, changes sensitively with increasing damage. The results are more significant than corresponding changes in eigen frequencies, as commonly used for structural health monitoring. Commonly detection systems use fast Fourier transformation (FFT) to extract system features and to determine the condition of the system from changes in the eigen frequencies. One drawback of this approach is that noisy excitation of the structure broadens the peaks of the frequency spectrum and thus makes it harder to detect changes reliably.
Yasin Kisioglu et.al,(2013)
• Hydraulic press design under different loading conditions using finite element analysis
this study, a suitable hydraulic press of straight sided four-pillar type as specified in Indian standard codal provisions is designed and the distribution of stress is calculated at its different structural members using analytical and finite element methods both in different loading conditions. They used Three different types loading such as axial loading eccentric loading and oblique loading, are considered in design press. They also tried it in Six different types of standard rolled steel sections having the same cross-sectional area used as columns for the press. So through this process they prepare Three different models of the press head to support the hydraulic cylinder. So eighteen different design combinations for a hydraulic press are they modeled under three different loading conditions. They calculated their stress distributions by using a computer-aided FEAM (finite element analysis method) tool and analytical formulas and the obtained results are compared. Two different types of finite elements, shell and beam, are used for the modeling processes. Based on the obtained results, the best model for the hydraulic press considering the head and body types is defined. and recommended that T type head and hollow circular or I-sectioned column is the best design consideration.
Martin Zahalka et.al, (2013)
• Modal analysis of hydraulic press frames for open die forging,
this study discusses the dynamic behavior of the forging machines when it is impacting on forging platform it was necessary to study separately because we have to increase the speeds of head on large forging hydraulic presses for open die forging. This study explains about the modal analysis of two different types of presses, which are popular in the most common designs of hydraulic presses for forging. The first press is with double-pillar frame CKV 50 with the force bearing capacity of 50MN and the second one is with four-pillar frame CKV 170 with the force bearing capacity of 170 MN. They had described the simulations of oscillation, which was excited by a specified time-dependent work force. Results of analysis have been compared with real experimental results performed in the actual. And they concluded that we can get higher second moment of area with the same area of cross section by changing of shape of cross section only.
Santosh kumar et al (2014)
• Analysis and structural optimization of 5 ton H-frame hydraulic press,
In above study author Discussed about designing the hydraulic presses frame the Using optimum resources like material and other accessories used. And their main aim was to analyze that can it really affect the total cost of the hydraulic presses or not. In the sense of reduction obviously. They mainly optimized or can say minimize the weight of material utilized for building the structure of press. They made an attempt in this direction to reduce the volume or quantity of material used in fabrication. So they considerd an industrial application project consisting of minimization mass of H-frame type hydraulic press. This press has to compensate the forces acting on the working plates and has to fulfill certain critical constraints. ANSYS has been used for this analysis the main aim is to reduce the cost of the Hydraulic presses without compromising on the quality of the output. With regarding to design specification, stress distribution, deflection, and cost, are focused on optimized design. The methodology followed in this work is comparison of stresses induced in machine for different thickness used for construction of frame and column of the H-frame type hydraulic press. In this project it has been compared original design of H frame type hydraulic press with design that have been optimized by using software (ANSYS) .
Since lot of work has been done on SHM of steel frame for both static condition the type of testing methods from analog to digital .
Further work has been done on structural analysis and optimization of loading frame and hydraulic presses we plant to replicate that for our loading frame
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