Effect of temperature and blank holder force on non-isothermal stamp forming of a self-reinforced composite

Kalyanasundaram, Shankar,Venkatesan, Sudharshan Techno-Press 2016 Advances in aircraft and spacecraft science Vol.3 No.1

Composite materials are rapidly gaining popularity as an alternative to metals for structural and load bearing applications in the aerospace, automotive, alternate energy and consumer industries. With the advent of thermoplastic composites and advances in recycling technologies, fully recyclable composites are gaining ground over traditional thermoset composites. Stamp forming as an alternative processing technique for sheet products has proven to be effective in allowing the fast manufacturing rates required for mass production of components. This study investigates the feasibility of using the stamp forming technique for the processing of thermoplastic, recyclable composite materials. The material system used in this study is a self-reinforced polypropylene composite material (Curv$^{(R)}$). The investigation includes a detailed experimental study based on strain measurements using a non-contact optical measurement system in conjunction with stamping equipment to record and measure the formability of the thermoplastic composites in real time. A Design of Experiments (DOE) methodology was adopted to elucidate the effect of process parameters that included blank holder force, pre heat temperature and feed rate on stamp forming. DOE analyses indicate that feed rate had negligible influence on the strain evolution during stamp forming and blank holder force and preheat temperature had significant effect on strain evolution during forming.

Why Do Startups Fail? A Case Study Based Empirical Analysis in Bangalore

Kalyanasundaram, Ganesaraman Asian Society for Innovation and Policy 2018 Asian Journal of Innovation and Policy Vol.7 No.1

In an entrepreneurial ecosystem, the failure rate of startups is extremely high at 90%, and every startup that fails becomes an orphan. This phenomenon leads to higher costs of failure for the entrepreneurs in the ecosystem. Failed startups have many lessons to offer to the ecosystem and offer guidance to the potential entrepreneur, and this area is not fully explored compared to the literature on successful startups. We use a case based method distinguishing a failed startup and a successful startup, studying the entrepreneurial characteristics and firm level factors which cause the failures, in the technology startup ecosystem of Bangalore. We study one of the modes of exit adopted by failed startup entrepreneurs and draw key lessons on causes that culminate in failures. We have identified that factors such as the time to minimum viable product cycle, time for revenue realization, founders' complementary skillsets, age of founders with their domain expertise, personality type of founders, attitude towards financial independence and willingness to avail mentorship at critical stages, will decisively differentiate failed startups from the successful ones. Accordingly, implications have been derived for potential entrepreneurs for reducing the cost of failures in the entrepreneurial ecosystem.

Successful vs. Failed Tech Start-ups in India: What Are the Distinctive Features?

Ganesaraman Kalyanasundaram,Sitaram Ramachandrula,Bala Subrahmanya MH 아시아기술혁신학회 2020 Asian Journal of Innovation and Policy Vol.9 No.3

The entrepreneurial journey is not short of challenges, and about 90% + tech start-ups experience failure (Startup Genome, 2019). The magnitude of the challenges varies across the tech start-up lifecycle stages, namely emergence, stability, and growth. This opens the research question, do the profiles of a start-up and its co-founder impact start-up success or failure across its lifecycle stages? This study aims to understand and identify the profiles of tech start-ups and their co-founders. We gathered primary data from 151 start-ups (Status: 101 failed and 50 successful ones), and they are across different lifecycle stages and represent six major start-up hubs in India. The chi-square test on status and start-up’s lifecycle stage indicates a noticeable correlation, and they are not independent. The Kruskal Wallis test was used to distinguish statistically significant profile attributes. The parameters distinguishing success and failure are identified, and the need to deliver customer experience is emphasized by the start-up profile attributes: Product/service, high-tech nature of a start-up, investor fund availed, co-founder experience, and employee count. The importance of entrepreneurial experience is ascertained with entrepreneur profile attributes: Entrepreneurial expertise, the number of prior and current start-ups, their willingness to start again in the event of failure, and age of co-founder, which is a proxy to learning and experience. This study has implications for entrepreneurs, investors, and policymakers.

Reactive Power Control and Neutral Current Elimination of Four Wire Five Level NPC Inverter based STATCOM using 3D-SVPWM Technique

Palanisamy R.,Karthikeyan D.,Vidyasagar S.,Kalyanasundaram V.,Selvakumar K.,Vijayakumar K.,Selvabharathi D. 대한전기학회 2021 Journal of Electrical Engineering & Technology Vol.16 No.4

In this paper, three phase four wire fi ve level Neutral Point Clamped Inverter (NPCI) based Static synchronous Compensator (STATCOM) is implemented for reactive power control and neutral current elimination. Three dimensional Space Vector Pulse Width Modulation (3D-SVPWM) control strategy is developed to control this 5-level NPC inverter. The behaviour of static synchronous compensator is analyzed and reactive power control is done using constant DC voltage. The objective of this compensating method is to provide balanced and sinusoidal source currents under unbalanced and nonlinear load conditions and reactive power control. The 3D-SVPWM technique provides reduced harmonic content in output voltage and current, controlled source current, minimized common mode voltage and improved output voltage. In 3D-SVPWM, switching pulses are generated with non-redundant switching states, which lead to reduce the complexity in switching time calculation and computational time is less. The highlights of the paper includes the neutral current is reduced to 0.25A, source current harmonics is minimized and it provides balanced and sinusoidal source currents with help of STATCOM compensation. The simulation and experimental results demonstrates the sinusoidal and harmonics free source current and minimized neutral current for four wire fi ve level NPCI based STATCOM.

Design of Polymeric Orthopedic Screws with Variable Stiffness and Multi-Objective Optimization of Injection Molding Process

Sunil Kumar Yadav,Arnab Sikidar,Dinesh Kalyanasundaram 한국정밀공학회 2023 International Journal of Precision Engineering and Vol.24 No.4

Background Orthopedic metallic screws even post healing causes ‘pinching eff ect’ and load infl ammation to the bone. In this work, the design and development of a novel metallic core and polymeric shell orthopedic screw is discussed along with optimization of manufacturing process. Methods A comparative 2D fi nite element study for pull-out test was conducted on HA, HB, HC, and HD standards of screws for approximately identical diameters to determine the type of threading for the proposed design of the novel orthopedic screw. The polymeric shell of the orthopedic screws was manufactured by injection molding process. The material used for manufacturing the polymeric shell was poly-l-lactic acid. Injection pressure, injection velocity, packing pressure and packing time of the injection molding process were optimized for the following output responses: maximum axial pull-out strength, and maximal bending strength of the screw. Results The r-squared and the adjusted r-squared value of the developed regression model for pull-out was found to be 96% and 92%, respectively. For the bending force, the developed regression model had a r-squared and adjusted r-squared value of 87% and 75%, respectively. The regression models were maximised to obtain the desired input parameters. The optimised parameters were validated experimentally at two local maxima for both pull-out and bending force. Signifi cance The developed screw is novel in design and a patent has been fi led under US patent offi ce with number US 2022/0000529 A1. The screws can be used by medical practitioners to avoid or minimise revision surgery and infl ammation.

A SVPWM Control Strategy for Capacitor Voltage Balancing of Flying Capacitor Based 4-Level NPC Inverter

R. Palanisamy,V. Shanmugasundaram,S. Vidyasagar,V. Kalyanasundaram,K. Vijayakumar 대한전기학회 2020 Journal of Electrical Engineering & Technology Vol.15 No.6

A Space Vector Pulse Width Modulation (SVPWM) control strategy is implemented for capacitor voltage balancing of Flying Capacitor (FC) based 4-level Neutral Point Clamped (NPC) inverter. This fl ying capacitor based 4-level NPC inverter is developed for medium voltage and high power applications. This system includes 6 power switching devices, 2 clamping diodes and 2 fl ying capacitors per leg. The fl ying capacitors ensure to operate inverter normally and all the switching devices share the voltage stresses in identical manner. Also it controls the voltage across each capacitor and maintained at V dc /3 times of applied dc voltage. The proposed SVPWM method takes advantage of utilizing redundancy switching states to control and balance the voltage across the capacitor using nearest switching state vector selection method. Moreover, this system provides reduced total harmonic distortion (THD), and minimized voltage stress. The control technique is implemented without using any look-up tables or eff ective logic tables or trigonometric functions. The simulation and experimental results of this proposed verifi ed are verifi ed using Matlab-simulink and FPGA controller respectively.

Dry Electrostatic Spray Coated Towpregs for Thermoplastic Composites

Vijay Goud,Ramasamy Alagirusamy,Apurba Das,Dinesh Kalyanasundaram 한국섬유공학회 2018 Fibers and polymers Vol.19 No.2

Though the processing steps for the manufacture of thermoplastic composites present little difficulty when compared to those for thermoset composites, it is not cost effective as a result of difficulty in accomplishing thorough infusion of resin into fibers and fibrous structures. Tremendously high viscosity for thermoplastic resin leads to numerous problems in the manufacturing process of thermoplastic composites. Pre-impregnation processes such as melt impregnation or solution impregnation, tend to form a stiff towpreg that cannot be used for any textile preforming operation. Powder coating can be a destined to be a cost effective as well as efficient processing technology to produce a flexible towpreg. A method for production of flexible towpregs for thorough infusion of resin into fibers using electrostatic spray gun, which involves powder coating a bundle of filaments is described. During the powder coating process using electrostatic spray gun, powder particles fetched by a conveying air stream, from a fluidizing hopper, are charged in the high voltage corona discharge by ion bombardment and transported to the fiber tow through the combination of electrostatic, aerodynamic and gravitational forces. Aerodynamic forces have the obligation to carry the powder particles to the tow where electrostatic forces dominate and cause the adherence of powder particles to the potentially grounded tow. After the powder deposition, tow is made to pass through convective oven where powder particles glue to the reinforcement as a result of partial liquefaction of the powder. The towpreg formed is then wound by the take up device. Take up device is equipped with dancerarm which ensures constant line tension and thereby consistent powder deposition. The effects of process variables of the electrostatic spray process such as corona voltage, fluidizing air pressure, conveying air pressure, distance of gun from tow and tow velocity on maximum powder deposition are investigated and reported.

Temporal Variation in Tiger Population in a Semi-Arid Habitat in India

Singh, Randeep,Pandey, Puneet,Qureshi, Qamar,Sankar, Kalyanasundaram,Krausman, Paul R.,Goyal, Surendra Prakash National Institute of Ecology 2022 국립생태원회보(PNIE) Vol.3 No.3

Understanding temporal variations in wildlife populations is a prerequisite for conservation planning of wide-ranging species such as tigers (Panthera tigris). We determined the temporal variation in abundance, population growth, and sex ratios at different age and sex stages for a tiger population in Ranthambhore Tiger Reserve, India from November 2007 to February 2011 using motion-sensing cameras. We identified 19 male and 21 female tigers from stripe patterns during 16,110 trap nights within an area covering 233 km². The annual abundance of the population varied from 34.9 (mean)±3.8 (SE) to 23.9±1.5, with a declining trend in the mean annual change of abundance (-12%). The density of adult females remained stable across the study duration, but the densities of adult males and non-breeding tigers fluctuated. The sex ratio was female-biased (0.58 males/female) for breeding tigers and male-biased (1.74 males/female) for non-breeding tigers. Our results reinforce the importance of long-term studies for monitoring the naturally occurring processes in populations to develop population indicators and identify reliable baseline information for conservation and management planning of populations.

Estimating Population Density of Leopards in Semi-Arid habitat, Western India

Randeep Singh,Puneet Pandey,Qamar Qureshi,Kalyanasundaram Sankar,Paul R. Krausman,Surendra Prakash Goyal National Institute of Ecology 2023 국립생태원회보(PNIE) Vol.4 No.2

The leopard (Panthera pardus) is one of the most widespread felids worldwide. Despite their wide distribution, reliable data on leopard population densities are still inadequate for conservation and management strategies in different landscapes. In the present study, we estimated leopard density using camera traps in the Ranthambhore Tiger Reserve (RTR), Rajasthan, India, between December 2010 and February 2011, where leopards coexist alongside a high density of tigers (Panthera tigris), a larger predator (RTR). A sampling effort of 4,450 trap days was made from 178 camera trapping stations over 75 days, resulting in 46 suitable photo captures (25 right flanks and 21 left flanks). In total, 18 individuals (7 males, 8 females, and 3 unknown sexes) were identified using the right flanks, and the estimated leopard density was 8.8 (standard error=2.8) individuals/100 km². Leopard density appeared to respond to small prey (<50 kg weight) richness. As this is the first systematic study to provide baseline information on leopard density in RTR, it could form a baseline for comparison in future investigations.

Deformation behaviour of steel/SRPP fibre metal laminate characterised by evolution of surface strains

Nam, J.,Cantwell, Wesley,Das, Raj,Lowe, Adrian,Kalyanasundaram, Shankar Techno-Press 2016 Advances in aircraft and spacecraft science Vol.3 No.1

Climate changes brought on by human interventions have proved to be more devastating than predicted during the recent decades. Recognition of seriousness of the situation has led regulatory organisations to impose strict targets on allowable carbon dioxide emissions from automotive vehicles. As a possible solution, it has been proposed that Fibre Metal Laminate (FML) system is used to reduce the weight of future vehicles. To facilitate this investigation, FML based on steel and self-reinforced polypropylene was stamp formed into dome shapes under different blank holder forces (BHFs) at room temperature and its forming behaviour analysed. An open-die configuration was used in a hydraulic press so that a 3D photogrammetric measurement system (ARAMIS) could capture real-time surface strains. This paper presents findings on strain evolutions at different points along and at $45^{\circ}$ to fibre directions of circular FML blank, through various stages of forming. It was found initiation and rate of deformation varied with distance from the pole, that the mode of deformations range from biaxial stretching at the pole to drawing towards flange region, at decreasing magnitudes away from the pole in general. More uniform strain distribution was observed for the FML compared to that of plain steel and the most significant effects of BHF were its influence on forming depth and level of strain reached before failure.