Visco Hydraulic (DSSV) Shock Absorber

In the Modern World where fast cars are becoming available to general public, the need of comfort and safety is becoming ever more important. Racing community has evolved to a point where a minute mistake can cost racer and his sponsors a lot. We are talking about Formula one, Desert rally and off-r

Project Title

Visco Hydraulic (DSSV) Shock Absorber

Project Area of Specialization

Mechanical Engineering

Project Summary

In the Modern World where fast cars are becoming available to general public, the need of comfort and safety is becoming ever more important. Racing community has evolved to a point where a minute mistake can cost racer and his sponsors a lot. We are talking about Formula one, Desert rally and off-road racing etc. For this purpose, a vehicle must have an adaptive suspension and damper which is essential for modern racing. Dynamic suspension spool valve dampers are particularly made for these applications.
The ride quality of conventional dampers is uncomfortable on varying road conditions, several active damping technologies like MR and ER damping are introduced which are rather expensive. The DSSV damper will provide similar ride quality to the active damping system and is cheaper and simpler when compared to these latest technologies.

Project Objectives

Adaptive damper with passive technology:
A DSSV damper can compete with the latest active damper technologies which include MR dampers, ER dampers and motorized hydraulic dampers. These technologies are much costly and only designed for luxury cars. DSSV dampers use a simple spring and sleeve assembly to provide adaptive damping which makes it much attractive when compared to the likes of other latest technologies that require complex designing and manufacturing. DSSV technology also has the upper hand in heat management when compared to other technologies.
Better damping than conventional systems:
A conventional damper uses shims (flexible disks) to cover and uncover the piston orifices whereas DSSV damper uses its spring-sleeve assembly (spool valve) to cover and uncover the orifices. The major benefit of this modification is that it now has better life than conventional ones as the flexible disk is subject to fatigue which affects its strength and stiffness. With the introduction of spool valve the life is enhanced and
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there is no change in the characteristics of orifice with respect to time and use.

Optimized design of spool valve aperture:
• Any desired force velocity curve characteristics can be obtained by using specifically designed orifice shapes. Different shapes of orifices can be used to obtain damping characteristics for different applications.
• Conventional shim dampers require excessive trial and error test to achieve required damping characteristics whereas DSSV damping characteristics can be mathematically predicted.
• DSSV dampers can be easily tuned whereas conventional shim dampers cannot be tuned according to varying road conditions
 

Project Implementation Method

Designing:
A DSSV damper can compete with the latest active damper technologies which include MR dampers, ER dampers and motorized hydraulic dampers. These technologies are much costly and only designed for luxury cars. DSSV dampers use a simple spring and sleeve assembly to provide adaptive damping which makes it much attractive when compared to the likes of other latest technologies that require complex designing and manufacturing. DSSV technology also has the upper hand in heat management when compared to other technologies.
3-D Modelling:
Developing the 3-D model of the damper components using SolidWorks and the assembly of these components. The main feature of our model is the spool valve assembly, two spool valve assemblies are designed independently for compression and rebound. By providing independent spool vale assemblies for compression and rebound the compression ad rebound curves can be tuned separately.
the compression ad rebound curves can be tuned separately.
Manufacturing:
Using the 3-D CAD model, the CNC code is generated and provided to the CNC machine for production of the parts of damper assembly. After production of parts, the damper will be assembled and inspected for any faults. After the faults and dissatisfactions are removed, we will proceed to the testing phase.
Testing:
After Fabrication, the damper will be tested on Shock Dynamometer Apparatus for data acquisition. After acquiring the data, the experimental and theoretical results are compared.

Benefits of the Project

This damper is designed, fabricated and assembled after in depth research of related field and market. As explained earlier, this damper finds its application in modern racing particularly in off-road racing and desert rallies. Off-road Racing industry is new in Pakistan and is gaining more attention with every passing year. We feel opportunities are wide open to be settle in this field. Local market is not producing premium off-road shocks and majority of people participating in rallies are importing it from outside Pakistan. Therefore, we have designed and manufactured this adaptive damper using passive technology which will provide a cost-effective solution to racing industry.
 

Technical Details of Final Deliverable

 Damper Fluid Mechanics:
Various types of oils can be used in dampers, the primary concern is that it should have low coefficient of thermal expansion and so that during high temperature the oil does not undergo expansion. Sometimes mineral oil can be used, and synthetic oil is even more reliable, but it is expensive. In any damper viscosity of the fluid is not necessary but it plays its role in lubrication and to minimize leakage.
While applying Bernoulli’s equation for the calculation of damping provided by the damper certain assumptions are made, of which first assumption is the density of the fluid which is assumed to be constant and fluid is assumed to be incompressible in nature.

Compressibilty:

“The density of a liquid is affected by the pressure, in a fairly linear way for practical damper pressures"
                              ????= ????????[????+????(?????????????)] 
Here, ? is the compressibility of the fluid, which is the reciprocal of the bulk modulus K. A mineral damper oil has very large hydrocarbon chains due to which they do not pack in compact manner thus giving a high compressibility than ordinary liquids like water which comprises of small water molecules. For pure oil bulk modulus is about 1.5GPa, and reference pressure P 1 about 1 atm. Pressure (101325 Pa) giving compressibility ? about 670 × 106/MPa = 0.07% /MPa. With required tolerance about 0.5% / MPa. In a practical damper the working pressure of 5 MPa will increase density by 0.35 %

Equation of continuity:
The equation of continuity is based on the principal of conservation of mass for fluids. The mass flow rate in is equal to the mass flow rate out assuming non-compressible fluid. If fluid is assumed to have constant density, then equation of continuity is better explained in terms of volume flow rate.
Bernoulli’s equation:
“Bernoulli’s equation is defined as the conservation of energy of flowing fluid assuming constant density. Bernoulli’s equation is valid for fluid with zero viscosity and fixed density only.” Bernoulli’s equation is expressed as:
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              ????????+????????????????????????+????????????????=????????+????????????????????????+????????????????

For damper technology there is very small change in the potential energy of the system so ?gh term can be neglected and Bernoulli’s equation is simplified as ????????+????????????????????????=????????+???????????????????????? (2.7)
Pipe flow:
“Flow through any pipe was investigated by the Osborne Reynolds, and he provided a criterion for determining the type of flow through pipe of any shape. He came out with a formula that indicates the flow type, either it is streamline, turbulent or transition flow (both). The criteria for this are the Reynold’s Number: ????????=???????????????? (2.8) For a circular cross section of the pipe

1. Re < 2000 Laminar flow
2. Re > 4000 Turbulent flow
3. 2000 < Re < 4000 Transition flow.

Final Deliverable of the Project

Hardware System

Core Industry

Manufacturing

Other Industries

Core Technology

Others

Other Technologies

Sustainable Development Goals

Industry, Innovation and Infrastructure

Required Resources

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