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Y. L. Jain et al.
1 Introduction
While developing EVs for Indian market, OEMs must take into consideration the
irregular road conditions such as steps and bumps and so in recent years, the focus is
also being shifted to have better and comfortable ride with higher segment vehicles.
Wide research has already been carried out for higher segment vehicle in order to
have maximum possible mileage at desired torque on bumpy or irregular roads and
it was observed that economy level drops down on irregular roads [1].
Also, due such irregularities, trend of torque requirement on such roads is shown
in Fig. 2. Coefficient of rolling resistance is tested as per standard defined by SAE
J1269, SAE J2452, and by ISO 18164:2005 (Europe). As per these standards, allowable coefficient of rolling resistance (CRR) is 0.007–0.014 for new tires. From Fig. 1,
it is clear that at as the tire pressure goes down, CRR is exceeding 0.014. Now
relating this with electric vehicle, coefficient of rolling resistance is directly proportional to battery consumption or event of battery recharging. It is clear that, to have
better battery life or having less event of battery recharging, we must either focus on
proposing and developing better roads or developing and optimizing the traditional
suspension system. The traditional telescopic suspension systems designed with low
cost have less maintenance and durable but it is insensitive to low height bumps. It
is observed with telescopic suspension system developed for two wheelers first time
in 1939 by BMW in USA [2]. Since then very few design modifications are seen in
mid-range bikes in front suspension. Nowadays, vehicles not only differ in engine
power or mileage but also in suspension characteristics [1]. Many two-wheeler manufacturers have developed their own technology for front telescopic suspension which
is of inverted type. The optimum behavior of this type of suspension is obtained by
changing the governing parameters [1]. Looking at variation in Indian road condition,
it is required to incorporate inverted telescopic suspensions in for electric bike as it
reduces the unsprung mass which leads to better and comfortable ride [3]. The springs
in front suspension are preloaded to have desired stability. Preload also helps in maintaining the height of the suspension to adjust vehicle weight. This preloading makes
the spring insensitive to road reactions and having lower value than the prestress
given to suspension springs [3].
Even after development of conceptual design of suspension system, question is
“how to evaluate or compare the performance with existing suspensions”? Experimental validations is one such process in development of suspension system which
completely relied on the rider perceptions of comfort and evaluation techniques [4].
Static and dynamic analysis/behavior with the help of parameters such as kinetic
energy, displacements, and velocities can be obtained with respect to change in time
[5]. The main objective of this study is to reduce the response/vibration or displacement level at bike handle which occurs due to road irregularities to have better and
comfortable ride. Current paper is focusing on optimization in existing suspension
system. Simplified model was developed in ADAMS for dynamic analysis and the
same is done on the conceptual model using ADAMS. Response level was recorded
at bike handle bar as displacement in Y-direction and recorded in the form of graphs
Y. L. Jain et al.
1 Introduction
While developing EVs for Indian market, OEMs must take into consideration the
irregular road conditions such as steps and bumps and so in recent years, the focus is
also being shifted to have better and comfortable ride with higher segment vehicles.
Wide research has already been carried out for higher segment vehicle in order to
have maximum possible mileage at desired torque on bumpy or irregular roads and
it was observed that economy level drops down on irregular roads [1].
Also, due such irregularities, trend of torque requirement on such roads is shown
in Fig. 2. Coefficient of rolling resistance is tested as per standard defined by SAE
J1269, SAE J2452, and by ISO 18164:2005 (Europe). As per these standards, allowable coefficient of rolling resistance (CRR) is 0.007–0.014 for new tires. From Fig. 1,
it is clear that at as the tire pressure goes down, CRR is exceeding 0.014. Now
relating this with electric vehicle, coefficient of rolling resistance is directly proportional to battery consumption or event of battery recharging. It is clear that, to have
better battery life or having less event of battery recharging, we must either focus on
proposing and developing better roads or developing and optimizing the traditional
suspension system. The traditional telescopic suspension systems designed with low
cost have less maintenance and durable but it is insensitive to low height bumps. It
is observed with telescopic suspension system developed for two wheelers first time
in 1939 by BMW in USA [2]. Since then very few design modifications are seen in
mid-range bikes in front suspension. Nowadays, vehicles not only differ in engine
power or mileage but also in suspension characteristics [1]. Many two-wheeler manufacturers have developed their own technology for front telescopic suspension which
is of inverted type. The optimum behavior of this type of suspension is obtained by
changing the governing parameters [1]. Looking at variation in Indian road condition,
it is required to incorporate inverted telescopic suspensions in for electric bike as it
reduces the unsprung mass which leads to better and comfortable ride [3]. The springs
in front suspension are preloaded to have desired stability. Preload also helps in maintaining the height of the suspension to adjust vehicle weight. This preloading makes
the spring insensitive to road reactions and having lower value than the prestress
given to suspension springs [3].
Even after development of conceptual design of suspension system, question is
“how to evaluate or compare the performance with existing suspensions”? Experimental validations is one such process in development of suspension system which
completely relied on the rider perceptions of comfort and evaluation techniques [4].
Static and dynamic analysis/behavior with the help of parameters such as kinetic
energy, displacements, and velocities can be obtained with respect to change in time
[5]. The main objective of this study is to reduce the response/vibration or displacement level at bike handle which occurs due to road irregularities to have better and
comfortable ride. Current paper is focusing on optimization in existing suspension
system. Simplified model was developed in ADAMS for dynamic analysis and the
same is done on the conceptual model using ADAMS. Response level was recorded
at bike handle bar as displacement in Y-direction and recorded in the form of graphs