HDPE Compound Testing for Molding and Compression Tests


Five (5) different compounds were manufactured with different ingredient volumes and material characterization testing was carried out. The blow moulding manufacturing process was simulated for all the 5 materials and the design has been analyzed in the principal deformation mode of compression.

The objectives of the project were:

  1. Manufacture the granules for the five (5) compounds as per the Marico recipes.
  2. Mould samples as per ASTM D638 for characterization tests.
  3. Carry out material characterization testing as per the standard SAE FEA protocol.
  4. Generate the material constants for use in the 500 ml blow moulding simulation process and compression crush tests.
  5. Examine the deformation pattern and resulting stresses and strains generated in the models for the five (5) material compounds and different wall thicknesses.
  6. Document the results for further engineering steps.

2.1 Characterization of Material Properties

a. Determination of the functional coefficients to use in nonlinear FEA utilizing results of experimental material test data.

The following material functions have been studied and used in this project for parameter generation:

1) Hyperelastic
2) Hypoelastic
3) Elastic
4) Elasto-Plastic

b. Non-Linear Finite Element Analysis (FEA).

b.1 Blow Moulding Process Simulation

The design assembly for a 500 ml bottle blow moulding process simulation shows a non-linear behavior because of the presence of polymeric material and numerous metal-polymer interface surfaces in the mould. A 3-dimensional model of the assembly was developed to model the designs incorporating all the nonlinearities. Contact surfaces and pressure loaded surfaces were incorporated in the model to account for perfect application of loading and boundary conditions.

b.2 Compression Test Process Simulation

The compression test simulation similar to the blow moulding simulation shows a non-linear behavior because of the presence of metal polymer contact interfaces and potential buckling model of local deformation. Contact pair based surface modeling strategy was utilized for the compression crush process simulations for the models with different wall thicknesses.


FEA results have shown the critical points of the 500 ml bottle material and geometry under blow moulding process and compression deformation. Prototype development and functional testing with judicious use of ingredients in the HDPE recipe as per the FEA investigations to avoid buckling at cap region geometrical discontinuities and local yielding had been recommended.


  1. ABAQUS Inc., ABAQUS: Theory and Reference Manuals HKS Inc., RI, 02
  2. Bathe, K. J., Finite Element Procedures Prentice-Hall, NJ, 96
  3. Dowling, N. E., Mechanical Behavior of Materials, Engineering Methods for Deformation, Fracture and Fatigue Prentice-Hall, NJ, 99.
  4. Vaidya, R., Structural Analysis Of Poly Ethylene Terephthalate Bottles Using The Finite Element Method, Master’s Thesis. 2012, Oklahoma State University
  5. M. Wortley, “Injection blow molding,” in Practical guide to blow molding, ed: Smithers Rapra Technology, 2006