Stress and Strength Evaluation of Double Lap Adhesive Joint.

This paper summarizes the evaluation of stress and strength of double lap adhesive joint. Stress and deformation of the double lap adhesive joint is obtained by finite element analysis using ANSYS and strength is obtained by experimental method. Joint failure is one of the main causes of interruption of rotating or stationary machinery operation. This generally leads to unscheduled shut down thereby increasing the cost of operations. One of the major concerns in adhesive joint is the detection of the rupture initiation and strength of joint before it develops into a failure of material. The ability to achieve strength of adhesive joint is essential to the optimal maintenance of whole system with respect to cost and productivity. The effects of the length of adherend, width of adherend, the overlapping length of the joint, the thickness of the adhesive layer and the initial impact velocity of the impacted mass on the double lap adhesive joint are studied. Early detection of the stresses and rupture in the joint are crucial for the prevention of damage to the system

EVALUATION OF THRUST FORCE IN DRILLING OF BD-CFRP COMPOSITE USING TAGUCHI ANALYSIS, RESPONSE SURFACE METHODOLOGY AND NEURAL NETWORK

Drilling is the most frequently used machining operation in carbon fiber reinforced polymer (CFRP) composite materials. The quality of the drilled holes is significantly affected by the thrust force generated during drilling of CFRP composite materials. In the present work, an attempt has been made to study the effects of process parameters such as feed rate, spindle speed, drill diameter and point angle on thrust force in drilling of bi-directional carbon fiber reinforced polymer (BD-CFRP) composite laminate using Taguchi design of experiments (DOE), the response surface methodology (RSM) and the genetic algorithm optimized radial basis function neural network (GA-RBFNN). The analysis of variance (ANOVA) is also performed for investigating the influence of process parameters on machining process using high speed steel (HSS) drills. The results reveal that the drill diameter is the most significant design factor influencing the thrust force followed by the spindle speed. It is evident from the investigation that the experimental results of the thrust force in drilling of BD-CFRP composite laminate are in good agreement with the predicted results as per RSM and GA-RBFNN

Handoffs in User-Centric Cell-Free MIMO Networks: A POMDP Framework

We study the problem of managing handoffs (HOs) in user-centric cell-free massive MIMO (UC-mMIMO) networks. Motivated by the importance of controlling the number of HOs and by the correlation between efficient HO decisions and the temporal evolution of the channel conditions, we formulate a partially observable Markov decision process (POMDP) with the state space representing the discrete versions of the large-scale fading and the action space representing the association decisions of the user with the access points (APs). We develop a novel algorithm that employs this model to derive a HO policy for a mobile user based on current and future rewards. To alleviate the high complexity of our POMDP, we follow a divide-and-conquer approach by breaking down the POMDP formulation into sub-problems, each solved separately. Then, the policy and the candidate pool of APs for the sub-problem that produced the best total expected reward are used to perform HOs within a specific time horizon. We then introduce modifications to our algorithm to decrease the number of HOs. The results show that half of the number of HOs in the UC-mMIMO networks can be eliminated. Namely, our novel solution can control the number of HOs while maintaining a rate guarantee, where a 47%-70% reduction of the cumulative number of HOs is observed in networks with a density of 125 APs per km2. Most importantly, our results show that a POMDP-based HO scheme is promising to control HOs.Comment: Accepted in IEEE Transactions on Wireless Communications (TWC

Surface runoff estimation using geographic information system and soil conservation service-curve number method for sub catchments of Karamadai, Tamil Nadu

Water conservation becomes essential as the resource becomes scarcer. The most important step in managing water resources is estimating watershed runoff generated from rainfall, as the runoff and rainfall are the key factors in determining water availability for surface storage and groundwater recharge. So, this study is mainly focused on estimating the surface runoff generated from the three sub-catchments of Karamadai, Tamil Nadu, India, using the heavy to extreme daily rainfall events received in the study area within the span of 20 years (2000–2019). The study was performed in the ArcGIS environment using remote sensing data. The SCSCN (Soil Conservation Service-Curve Number) method was used to estimate surface runoff. The changes in the land use in each sub-catchment were analysed in each decade and studied for their impact on the runoff depth. The land use and land cover classification map of the study area was prepared from LISS III satellite imagery for the years 2006 and 2016 by using supervised classification. The curve number was assigned based on land use as well as the hydrologic soil group. The weighted curve number was calculated from the area under each land use and then used to calculate storm runoff. The maximum runoff occurred in 2011 in all the catchments of the Karamadai block. It was found that more runoff occurred in the Mandrai Pallam catchment compared to Periya Pallam and Pare Pallam, as the Mandrai Pallam catchment had less soil moisture retention capacity than the other two catchments. So, more priority must be given to this catchment while planning to implement the soil and water conservation measures

Artificial Inclusion Environments—Replicating Industry in the Laboratory

The authors present a series of complementary test methods which were developed and used to investigate reactions between high aluminium steel and silica rich inclusions. Non-metallic inclusions (NMIs) cause many defects in the final steel product, therefore the ability to track their size, morphology and composition and correlate this with fundamental reaction kinetics provides important knowledge to support the production of clean quality steel products. Novel steel grades such as TRIP, TWIP and low-density steels have high aluminium contents; aluminium is a readily oxidisable species presenting the potential for instability and excessive reaction with commonly used mould powders that contain silica. A novel combination of techniques including HT-CLSM (High-Temperature Confocal Laser Scanning Microscope), XCT (X-ray computed tomography) and SEM/EDS (scanning electron microscopy/electron dispersive spectroscopy) have been used to study the interaction of entrained mould powder inclusions with steel at high temperatures simulating industrial conditions. This report presents a discussion on the development of techniques and samples to achieve representative and repeatable results that can provide information on the complex chemical and physical interaction phenomena with confidence. Each experimental technique had its own learning points and consequent results. Outcomes presented include possible confirmation of the chemical reaction rate controlling step being aluminium mass transfer; heterogeneous local environmental conditions including fluidity and chemical composition; and occurrence of spontaneous emulsification where the mould powder inclusion breaks apart into a cloud of smaller fragments

The spontaneous emulsification of entrained inclusions during casting of high aluminum steels

Mold slag entrainment during the continuous casting process presents a late stage source of non-metallic inclusions (NMI) with a high likelihood of ending up in the final product. The reaction between the entrained slag phase and surrounding liquid steel in the continuous casting mold affects the inclusion morphology and properties. However, there is a lack of information on the kinetics of the NMI-steel reaction. A novel approach, utilizing controlled synthetic inclusion/metal samples, has been developed to study the reactions between free inclusion-slag droplets and steel. The technique combines High-Temperature Confocal Scanning Laser Microscopy (HT-CSLM), X-ray Computed Tomography (XCT) and advanced electron microscopy techniques offering rapid controlled heating performance and extensive characterization of the samples. This method offers the ability to observe the size, shape and composition of an unconstrained reacting inclusion and to investigate the interface between the materials with respect to reaction time. This study interrogates a low aluminum steel (0.04 wt pct) and a high aluminum steel (1 wt pct) in contact with an inclusion-slag phase with a starting composition aligned to a typical mold slag. It was found that the reaction between silica and aluminum across the interface of the two phases provided a driving force for spontaneous emulsification to occur. Products of such emulsification will have a significant effect on the inclusion size distribution and potentially the prevalence of inclusion retention in molten steels solidifying in the continuous caster (for example if emulsified buoyancy forces are reduced to near zero) and hence in the subsequent solid product