Week 10 Bullet penetrating a Bucket Challenge

SIMULATION OF BULLET PENETRATING INTO A BUCKET USING ANSYS WORKBENCH
OBJECTIVE
To simulate bullet penetrating into a bucket for different cases of bucket material,
Case-1: Al1100 - O
Case-2: Nikel All
Case-3: Copper 
To find out Total deformation and Equivalent stress developed in bucket for each case and compare the results.

1. THEORY
1.1 Bullet Penetration:
A bullet is a projectile, often a pointed metal cylinder, that is shot from a firearm. The bullet is usually part of an ammunition cartridge, the object that containsthe bullet and that is inserted into the firearm.
Bullets are made of a variety of materials. Lead or a lead alloy is the traditional bullet core material. Traditional bullet jackets are made of copper or gilding metal,an alloy of copper and zinc. There are many other materials that are used in bullets today, including aluminium, bismuth, bronze, copper, plastics, rubber, steel,tin, and tungsten.

Modern bullets can have many different features. Some of these features concern the shape of the bullet and others the materials of construction. Most bulletslook like a cylinder with a pointed end. The cylindrical section to the rear of the bullet is the shank and the pointed section to the front of the bullet is the tip,though the tip may be flat instead of pointed. Bullets can be made of one or more materials.

Bullets made out of only soft material (such as lead) expand on impact causing more damage to the target. Bullets made out of only a harder material (such assteel) penetrate further into thicker targets, but do not expand much. A softer core can be enclosed or partially enclosed in a layer of harder metal called ajacket. This jacket can completely enclose the bullet or it can leave the softer tip exposed for expansion purposes. Varying the amount of jacketing alters theamount of penetration versus expansion.

In this project a truncated cone shaped bucket made of materials like Case-1: Al1100- O Case-2: Nikel All
Case-3: Copper , is hit with a bullet travelling ata speed of 139000 mm/s.
The results are drawn to study the impact of the bullet on the bucket, as well as the behaviour exhibited by the material of the bucket.

2. ANALYSIS SETUP
2.1 Geometry:

Fig.2.1 3D model of bucket and bullet setup.

The given 3D model of bucket and bullet setup assembly is imported into SpaceClaim. It consists of a bucket and a bullet.

2.2 Material Properties:

Fig.2.2 Material property details of bucket and bullet.

The material assigned for bullet is tantalum, and for bucket, following materials are assigned for each case,

Case-1: Al1100 - O
Case-2: Nikel All
Case-3: Copper 

The stiffness behaviour of bullet is chosen as ‘rigid’.

2.3 Meshing:

.

Meshed model

Fig.2.3 Meshing details of bullet and bucket models.
The element size of bucket is refined to 15 mm using edge sizing option. The total number of nodes and elements generated are 4164 and 10965 respectively

Edge sizing of bucket.

2.4 Boundary Conditions:
2.4.1 Analysis settings:

Fig.2.4.1 Analysis settings.
In the analysis settings the number of steps considered is 1.
The end time specified is 1e-002.
The maximum no. of cycles is 1e+07.

The maximum energy erroris 2
The initial, minimum and maximum time step is set to ‘Program Controlled’.

2.4.2 Boundary condition for bullet penetrating into a bucket:

a. Fixed support.

2.4.2 Boundary condition for bullet penetrating into a bucket:

The bottom surface of the bucket is fixed. The bullet is directed to hit the bucket with a velocity of
139000 mm/s in negative x-direction.

3. RESULTS AND DISCUSSIONS

Total Deformation

Equivalent Stress

Equivalent Elastic Strain

Energy Plots

Solver Output

Energy Conservation

3.5 Comparison of Results:

CONCLUSION
Simulation of bullet penetrating into a bucket was carried out successfully for the following cases of bucket material,
Case-1: Al1100 - O
Case-2: Nikel All
Case-3: Copper 

The maximum distance travelled by bullet by penetrating in and moving out of the bucket is maximum for Al1100-O.

The v-m stress developed for Nickel All is maximum compared to other cases, because the value of yield strength and Poisson’s ratio of stainless-steel NL is lesscompared to other cases.

Generally, the effect of penetration of the bullet into a metallic object depends upon the thickness and density of the material.