(SEM VII) THEORY EXAMINATION, 2022-23 VEHICLE BODY ENGINEERING& SAFETY

SECTION A (2 Marks Each)

(a) Importance of Vehicle Body Design

Vehicle body design ensures safety, comfort, aesthetics, aerodynamics, and structural strength while protecting passengers and improving vehicle performance.

(b) Vehicle Layout

Vehicle layout refers to the arrangement of major components like engine, transmission, passengers, and luggage within the vehicle.

(c) Aluminum Used for Car Bodies

Mainly aluminum alloys such as 5xxx and 6xxx series are used due to light weight, corrosion resistance, and good strength.

(d) Structural Timber

Structural timber is treated wood used in vehicle bodies (earlier buses and coaches) for framing due to strength and flexibility.

(e) Basics of Aerodynamics

Aerodynamics deals with airflow around a vehicle to reduce drag, improve stability, fuel efficiency, and performance.

(f) Aerodynamic Forces and Moments

They include drag, lift, side force, and moments like pitching, rolling, and yawing moments.

(g) Interior Ergonomics

Interior ergonomics focuses on driver comfort, safety, posture, reachability, and ease of operation of controls.

(h) Window Winding Mechanism

It is a mechanism used to raise or lower vehicle windows, either manually or electrically.

(i) Difference Between Noise and Vibration

Noise is unwanted sound, while vibration is mechanical oscillation of components.

(j) Measurement of Noise Levels

Noise levels are measured in decibels (dB) using a sound level meter.

SECTION B (10 Marks Each – Attempt Any Three)

(a) Eight Systems of a Car

The eight systems are engine system, transmission system, suspension system, steering system, braking system, electrical system, cooling system, and body system. Each system works together to ensure safe, smooth, and efficient vehicle operation. (Neat sketches to be drawn in exam)

(b) Metal Matrix Composites (MMC)

Metal matrix composites consist of a metal matrix reinforced with fibers or particles to improve strength and stiffness.
Applications include automotive parts, aerospace components, and brake systems.
They are manufactured using stir casting, powder metallurgy, and infiltration methods.

(c) Types of Drag on a Car

Drag types include form drag, skin friction drag, induced drag, and interference drag. These affect fuel consumption and vehicle stability.

(d) Ergonomics and Its Importance

Ergonomics is the science of designing vehicles to fit human capabilities and limitations. It improves safety, reduces fatigue, enhances comfort, and increases driving efficiency.

(e) Sources and Types of Noise

Noise sources include engine, exhaust, road-tyre interaction, wind, and transmission.
Types include airborne noise, structure-borne noise, and impact noise.

SECTION C (10 Marks Each)

Q3

(a) Calculation of Approach and Departure Angles

Approach angle is the maximum angle a vehicle can climb without front body contact, while departure angle is the maximum angle it can descend without rear contact.
They depend on wheelbase, ground clearance, and overhang length. (Neat sketches required)

(b) Double Skin Construction

Double skin construction uses two layers of body panels with a gap between them to improve strength, noise insulation, and safety. It is commonly used in buses and coaches.

Q4

(a) Glass Reinforced Plastic (GRP)

GRP consists of glass fibers embedded in plastic resin.
Advantages include light weight, corrosion resistance, and good strength.
Disadvantages include low heat resistance and difficulty in repair.

(b) Thermoplastics

Thermoplastics soften on heating and harden on cooling.
Examples include polyethylene, polypropylene, PVC, nylon, and polystyrene.

Q5

(a) Wind Tunnel Technology

Wind tunnel technology studies aerodynamic behavior of vehicles.
Main parts include contraction cone, test section, diffuser, drive system, and flow straighteners.

(b) Weight Distribution of a Car

Vehicle weight is distributed between front and rear axles based on engine position, load, and design. Proper distribution improves stability and braking. (Neat sketches)

Q6

(a) Types of Vehicle Layouts

Layouts include front-engine rear-wheel drive, front-engine front-wheel drive, rear-engine rear-wheel drive, and mid-engine layout.
Front-engine front-wheel drive is most suitable for mass automobile manufacturing due to compact design and cost efficiency.

(b) Motion of a Car on Curvilinear Path

A car moving on a curved path shows curvilinear motion involving centrifugal force and lateral acceleration. (Neat sketches)

Q7

(a) Bearing Vibration

Bearing vibration is caused by wear, misalignment, imbalance, lubrication failure, and surface defects, leading to noise and reduced life.

(b) Force in Mechanics of Deformable Bodies

Force causes deformation in bodies. Analysis is complex because deformation depends on material properties, geometry, and loading conditions.