Polymeric composite shield design for ballistic impact protection
Lead Research Organisation:
Imperial College London
Department Name: Aeronautics
Abstract
Composite materials are being used in ballistic protection systems due to their combination of high strength and low density. One of the most promising materials is the Ultra-High-Molecular-Weight-Polyethylene (UHMWPE) fibre-reinforced polymeric composite due to its lightweight nature and excellent projectile capturing capabilities. This led to the material's extensive use in either soft or hard ballistic protection systems, with applications ranging from vehicle to body armour products. Therefore, it is important to develop a physically sound virtual design methodology in order to predict and optimise the impact performance of polymeric shields.
The aim of this project is to build an accurate and computationally efficient constitutive model that predicts the behaviour of UHMWPE composite laminates under high velocity impact events. The aforementioned composite material consist of UHMWPE filaments and an optimised resin. These filaments have shown a hierarchical morphology and a fibrillar nature, meaning that they consist of smaller scale fibrils, called macro-fibrils. Hence, special consideration should be given in the microstructure of the system and the way it affects the deformation, overall mechanical behaviour and failure mechanisms of the laminate. A multi-scale design approach is adopted from the macro-fibril level to the full-scale polymeric shield panel:
UHMWPE single fibre modelling, Representative Volume Element modelling, Continuum level constitutive modelling and Polymeric composite shield design.
The aim of this project is to build an accurate and computationally efficient constitutive model that predicts the behaviour of UHMWPE composite laminates under high velocity impact events. The aforementioned composite material consist of UHMWPE filaments and an optimised resin. These filaments have shown a hierarchical morphology and a fibrillar nature, meaning that they consist of smaller scale fibrils, called macro-fibrils. Hence, special consideration should be given in the microstructure of the system and the way it affects the deformation, overall mechanical behaviour and failure mechanisms of the laminate. A multi-scale design approach is adopted from the macro-fibril level to the full-scale polymeric shield panel:
UHMWPE single fibre modelling, Representative Volume Element modelling, Continuum level constitutive modelling and Polymeric composite shield design.
Organisations
People |
ORCID iD |
| Lorenzo Iannucci (Primary Supervisor) | |
| Dimitrios Kempesis (Student) |
Publications
Kempesis D
(2021)
A representative volume element model for ultra-high-molecular-weight-polyethylene composites
in Composite Structures
Studentship Projects
| Project Reference | Relationship | Related To | Start | End | Student Name |
|---|---|---|---|---|---|
| EP/N509486/1 | 01/10/2016 | 31/03/2022 | |||
| 2296879 | Studentship | EP/N509486/1 | 01/10/2017 | 31/03/2021 | Dimitrios Kempesis |
| Description | The behaviour of polymeric composites is controlled by phenomena that manifest in the smaller scales and propagate to the rest of the structure. Understanding the mechanics of these features is key to optimising the laminate's impact performance. A modelling methodology based on the microstructure has been established and four different length scales have been investigated starting from the nanometre level up to full scale polymeric shields. This computational design framework has been followed to characterize the non-linear, time and temperature dependent behaviour of polymeric composites as well as identify the nature of non-linearities observed in experiments. The sub-structure of the fibre, which is the main load carrying component of the laminate, has been explicitly modelled to provide insight on the stress and strain fields developing in the microstructure. This was an important step which allowed the identification of localisation regions that could potentially affect the overall strength of the laminate. Furthermore, phenomenological relations have been derived to express the effects that propagate from smaller scales to the continuum level response. The contribution of the observed phenomena has been implemented in a constitutive model that describes the behaviour of polymeric laminates. The coupling of the non-linear material model with hydrodynamic effects has also been incorporated leading to a more complete representation of the physics under high velocity impacts. The actual composite structure was also prone to manufacturing defects which introduced a level of variability in the properties. Hence, the stochasticity of the laminate's strength has been considered to derive probability levels on the ballistic limit of the polymeric shield. Two formulations have been proposed for the constitutive model and were assessed based on accuracy and computational efficiency. To ensure the proposed design methodology is applicable to ballistic protection systems, all the models were validated against experimental results found in the open literature. |
| Exploitation Route | Polymeric composites are widely used in the Aerospace and Defence sector to build impact protection systems. The numerical tools that were developed in this study can be used to optimize the architecture of polymeric shields and tailor material properties to achieve the desired performance. Extra focus has been given to the micromechanics and the effects that propagate from smaller to larger scales. However, developing and running microscale models can be both time consuming and computationally inefficient and might not be the most attractive solution for industrial applications. Hence, the outcomes of this work, both data and numerical models, could be used to train machine learning algorithms that provide solutions with comparable accuracy, to the original models, in a fraction of the computational time. |
| Sectors | Aerospace, Defence and Marine |