Hood design-Week 2

OBJECTIVES:-

• Designing and modeling the hood concerning its parameters and requirements.

INTRODUCTION:-

• Hood is an automobile component and it is called the bonnet in british countries.
• It is assembled in a tapered position to the windscreen of the car it has enclosed around the engine compartment.
• A hood is meant to protect the vehicle's performance parts like the engine or battery. T
• hey also provide easy access to car repair and maintenance.
• The hood is made up of aluminum materials.
• They serve a great deal of purpose in protecting the passengers inside the car and pedestrians in event of an accident.

HOOD COMPONENTS:-

• Hood outer panel
• Hood inner panel
• Latch and striker
• Reinforcements

OUTER PANEL:-

• The outer panel has an aesthetic look to it but on its own is very weak and not capable of handling force during impact.
• It is installed over the inner panel and made up of aluminum alloy.
• Aluminium alloy has excellent corrosion resistance and it possesses high strength and excellent stretch forming and lightweight characteristics.

INNER PANEL:-

• The inner panel is mounted under the outer panel.
• It has been designed and modeled with overlapping flange connected.
• The mess is created under the manufacturing process of sheet metal stamping dies.
• The purpose of the hood inner panel is providing to improve rigidity, durability, and pedestrian protecting performance by compressing a composite structure.
• The inner hood panel also protects the engine compartments during the collision.
• Generally the hood inner panel has a multi-cone structure.

HINGE:-

• The working system of the hood is completely based on its hinges.
• The hinge mechanism is provided that allows a lawn and garden tractor hood to be pivoted between closed and open positions.
• The construction of hinges to allow easy separation or connection of parts at the hinge axis in a radial direction requiring a specific angular position the pin having a non- circular cross-section
• The hinges are properly aligned on a single reference axis path.

To assemble the hinges, two constraints are used.

• Touch constraint
• Parallel constraint.

STRIKER:-

• A vehicle hood latch and release mechanism are latched when the hood striker engages the latch portion of the mechanism as the hood is moved to its closed position.
• The mechanism is actuated to release the hood striker by pushing action on the cable.
• When the latching mode of the hood latching and releasing mechanism latches the hood striker holds the hood closed.

REINFORCEMENTS:-

• The striker reinforcements material that can enhance strength and rigidity in the vicinity of the striker and secure pedestrian protection performance.
• The reinforcement is included for the less thickness of material where the deformation occurs at the time of the collision to protect pedestrians.

ASSEMBLY TREE OF HOOD:-

LATCH TRAJECTORY MOTION:-

• The significance of the trajectory concept is open and close the hood along the curved path to its motion concerning gravity.
• The circle is sketched at the center section of the hood using the datum plane and the line is drawn tangent to the circle.
• A perpendicular line is drawn at the center of the striker using the datum plane.
• By using the align constraint, coincident the tangent line and perpendicular line of striker.

MASTIC DATA:-

• The mastic sealants are in the form of paste.
• The mastic sealants either join one surface to another or adheres to nearly any material.
• The mastic sealants are applied in between the outer panel and inner panel to join with each other.
• The mastic data are applied on the hood and it solidified fills the gap of 5mm between the outer panel and inner panel.
• Hood commonly possess large surface area and hemming can only be provided through its boundary.
• Mastic sealants are elastic compound that behave like rubber.
• It is applied between the inner and outer panels at specified spots.
• Each spot of mastic sealants has its effect around a circular region from 50-80mm diameter.
• Thus, the mastic points are arranged in such a way that it covers the areas away from the hemming which are more vulnerable to vibrate.

EMBOSS:-

• This command enables modifying the sheet body by adding faces of a solid body.
• The target sheet body intersects with tool bodies when pressed.
• The shape of the tool bodies is to be transferred onto the sheet body.
• It increased the metal panels and stiffness and rigidity.
• Increase the surface area for heat transfer or acoustic applications and improve the traction.

MASTER SECTION:-

HEMMING PROCESS:-

• Hemming is a technology used to join inner and outer closure panels together.
• It is the process of bending/folding the flange of the outer panel over the inner panel.
• Hemming is performed to achieve a better final geometry in the vehicle part.
• Allow safe handling of the part.
• Add resistance and rigidity to the part.
• We are using the roller hemming operation for the hood to get the desired final shape of the product of the sheet.

• Numerical quantification of model and experiment of external

• To prevent the formation of buckling during hemming make the corner relief at the sharp corners.

PEDESTRIAN SAFETY:-

• The term pedestrian generally refers to a person walking, running, skating, skateboarding, and other similar devices.

Kinematics of pedestrians in an impact

• It describes when a passenger car collides with an adult pedestrian standing erect.
• The contact between the leading edge of the hood and the upper legs/pelvis of the pedestrian.

Adult and child head impact

• The impact area for the child's head is between 1000WAD- 1700WAD.
• The adult head impact area is between the 1700WAD-2100WAD. The impact area does not include the windscreen.

Virtual crash simulation

Requiring factors of the virtual crash test

• Creating the three-dimensional geometric models of all the required components to replicate structure as accurately as possible.
• Converting the geometric models into FE models.
• Implement the mass properties and representative materials properties.
• Constraining the components together.
• Post-processing to analyze the crash results.

Contour plot of hood displacement using hyper view

Conclusion:-

Designed and modeled the hood panel using Siemens NX CAD as per the design parameters.