Body and Frame: Description and Operation
Car body
Car body design
The XC90 is based on a passenger car chassis with unitary construction. This gives a low center of gravity, ensuring good directional stability and countering any tendency to roll over.
The shape of the XC90 body is based on the same basic design as the V70 body. Front and rear crumple zones absorb collision forces. The passenger compartment has a safety cage in which the door sills, posts, cantrails and doors are reinforced.
An aluminum member is spot-welded and screwed into place between the ends of the front side members. Steel plugs have been pressed into the aluminum member so that it can be welded into place.
The members in the front and rear doors form an important part of the reinforcement of the passenger compartment. The members are manufactured of boron steel.
Body with extremely high torsional rigidity.
A rigid body has a positive impact on active safety, sound level and collision safety (particularly in the event of side impacts).
There are two types of chassis applications, soft (USA) and hard (EU).
Surface treatment/Outer panels
1. Panels
2. Zinc
3. Phosphate
4. Primer
5. Undercoat
6. Paint
7. Clear varnish
8. Underseal.
Paint
All paints are water based.
Passive safety
In terms of collision safety, the XC90 has the same design solutions found in other Volvo cars. An SUV is a tall vehicle. This means that in a collision, it will hit other cars at a higher level than a passenger car.
To reduce the risks of damage and injury from this type of impact, the front end subframe has been supplemented with a lower crossmember which is at the same height as the bumper on a conventional passenger car. This lower member is integrated in the structure of the XC90 and is hidden behind the spoiler. This reduces the damage to the other car, allowing its safety system to be fully utilized.
Front crumple zone
- In the front crumple zone the collision forces are transferred to the heavily reinforced passenger compartment by three braking crumple zones
- Two lower crumple zones, the front side members and the subframe transfer the force on to the body through the door sills and floor
- The upper crumple zone, the upper side members transfer the force onwards to the body through the A-post and on to the cantrail and roof
- The collision force which goes via the A-post is also transferred to the doors.
Rear crumple zone
In the rear crumple zone, the collision force is transferred via the rear side members to the door sill and floor, and to the cantrail and roof via the D-post.
The doors, which are an important part of the passenger compartment reinforcement also absorb much of the collision force.
Side crumple zones
In the event of a side impact, the collision force is absorbed by the reinforced door sills and the A and B posts.
The roof member and part of the B-posts are made of brushed steel.
High strength steel / Boron Steel
HSS steel, general
Certain parts of the body are manufactured of steel with an increased yield and breaking point. HSS steel is used for a number of reasons:
- Partly to save weight, HSS plate is thinner than standard plate without compromising on the resistance and strength of the component
- partly when a component or section needs to be reinforced. For example at the sides where the body needs to be reinforced for greater impact protection.
Boron steel, general
Boron steel has particular advantages over other hardened steels. In particular it is very tough, yet can also be welded and shaped during manufacture. It also has a high resistance to fatigue and wear.
Boron steel is extremely hard and cannot be aligned or machined.
Galvanized body components
Galvanizing, general
There are three different methods when surface treating the body
- Electrolytic zinc galvanization
- Hot-dip zinc galvanization
- Hot-dip galvanization.
The method which is used for a particular component depends on factors such as where it will be used in the car. It may be treated on both side or only on one side, depending on whether it is an external component which needs a smooth surface or not.
Galvanized body components
All outer panels are galvanized except the roof.
Panel materials
Painted plastic components
The front and rear bumper covers are partly painted in the same color as the car.
The tailgate is painted the same color as the car.
Plastic components
Trim molding, sill trim panel, door mirrors and fender extension moldings are not painted.
Headlamps
The headlamp lenses are made of transparent plastic.
Aluminum/ Plastic
Aluminum
- The front bumper rail is made of aluminum. The bumper rail is point welded and screwed into position. Steel plugs have been pressed into the aluminum member so that it can be welded into place in the ends of the front side members.
Plastic
- The upper tailgate is made of plastic. Only available as a complete replacement part
- The drain hose for the sun roof in the A and D posts is made of plastic.
Two piece tailgate
Plastic / Sheet metal
- The upper section of the tailgate is manufactured from Urethane plastic with 30% glass fiber
- The tailgate consists of a frame and an outer panel which are bonded together. The outer panel cannot be replaced. Glass fiber and plastic adhesive is used for repairs
- The lower tailgate is made of sheet metal and can withstand a load of 150 kg when folded down.