Short answer

When designing for impact resistance, consider using auxetic structures and explore the use of strain-rate sensitive polymer foams as fillers to enhance energy absorption capabilities.

Field: Modelling
Source: Advanced Engineering Materials (2017)
Method: Experimental testing and simulation
Evidence: Strong effect

Incorporating strain-rate sensitive polymer foams into auxetic lattice structures significantly improves their ability to absorb impact energy compared to unfilled structures. This modelling research insight is drawn from a 2017 study published in Advanced Engineering Materials. Using Experimental testing and simulation, researchers explored how this design variable affects real-world outcomes. The key design takeaway: When designing for impact resistance, consider using auxetic structures and explore the use of strain-rate sensitive polymer foams as fillers to enhance energy absorption capabilities.

Study

ModellingHigh ImpactStrong effect

Auxetic structures with polymer fillings enhance energy absorption by up to 40% under dynamic impact

Incorporating strain-rate sensitive polymer foams into auxetic lattice structures significantly improves their ability to absorb impact energy compared to unfilled structures.

Advanced Engineering Materials · 2017

Key Findings

01Polyurethane foam filling increased specific absorbed energy by 5-40% compared to unfilled auxetic structures under dynamic impact.
02Ordnance gelatine filling resulted in a 5-10% increase in specific absorbed energy.
03Both the auxetic structures and the filler materials exhibited strain-rate dependent properties.
04Filling influenced the achievable negative Poisson's ratio values.

Application

Design takeaway

When designing for impact resistance, consider using auxetic structures and explore the use of strain-rate sensitive polymer foams as fillers to enhance energy absorption capabilities.

How to apply

Investigate the use of auxetic core structures filled with specific viscoelastic foams for applications such as protective padding, vehicle impact absorption, or sports equipment.

Project actions

01When selecting materials for impact absorption, consider not just the material's inherent properties but also how it interacts with the structure's geometry.
02Dynamic testing methods like the Split Hopkinson Pressure Bar are crucial for understanding performance under real-world impact scenarios.

Method & Evidence

AimTo investigate the impact performance of auxetic lattice structures filled with strain-rate sensitive materials and quantify the enhancement in energy absorption and changes in mechanical properties.

MethodExperimental testing and simulation

ProcedureAuxetic lattice structures (2D missing rib, 2D re-entrant honeycomb, 3D re-entrant honeycomb) were fabricated and filled with no filling, low expansion polyurethane foam, or ordnance gelatine. Samples were subjected to both quasi-static and dynamic compression tests using a Split Hopkinson Pressure Bar. Digital image correlation was employed to measure in-plane displacement and strain fields. Ratios of dynamic to quasi-static plateau stresses and specific energy absorption were calculated.

ContextMaterials science and mechanical engineering, specifically focusing on impact mechanics and advanced material structures.

Variables

IV["Type of auxetic structure (2D missing rib, 2D re-entrant honeycomb, 3D re-entrant honeycomb)","Type of filling (no filling, polyurethane foam, ordnance gelatine)"]

DV["Plateau stress","Specific energy absorption","Poisson's ratio","In-plane displacement and strain fields"]

CV["Loading rate (quasi-static vs. dynamic)","Sample dimensions","Testing apparatus"]

Strengths & Limitations

Strengths

+Utilized advanced testing equipment (Split Hopkinson Pressure Bar) for dynamic impact analysis.
+Employed Digital Image Correlation for detailed strain field analysis.

Limitations

The cost and complexity of specialized testing equipment like a Split Hopkinson Pressure Bar can be a barrier. The range of materials and structures tested may not cover all possibilities.

Reliability & validity

The use of a Split Hopkinson Pressure Bar and Digital Image Correlation provides a high degree of reliability and validity for dynamic mechanical testing. However, the sample size and specific material properties tested might limit generalizability.

Think critically

How might the scale and manufacturing precision of the auxetic structure influence the effectiveness of the polymer filling?

Design Principles

"Composite structures combining geometric anisotropy (auxetics) with material strain-rate sensitivity can achieve superior dynamic energy absorption."

This research offers a pathway to designing advanced protective materials and impact-absorbing components. By understanding how different fillings interact with auxetic geometries under dynamic loads, designers can create more effective solutions for applications requiring high energy dissipation.

What This Means for Your Design

Adding certain types of foam to special 'pull-apart' structures makes them much better at absorbing crash energy.

How to use in your project

1.Use this study to justify the selection of specific materials and structural designs for impact-related design challenges.
2.Cite findings on energy absorption enhancement when discussing the performance of your own design prototypes.

Add to My Project

Quick Cite

Paragraph starter

Research indicates that composite structures incorporating auxetic geometries and strain-rate sensitive polymer fillers can significantly enhance energy absorption under dynamic impact. For instance, studies have shown that filling auxetic lattices with polyurethane foam can increase specific absorbed energy by up to 40% compared to unfilled counterparts, highlighting the potential for such combinations in protective design applications.

Source

Advanced Engineering Materials

Impact Testing of Polymer‐filled Auxetics Using Split Hopkinson Pressure Bar

journal · 2017

View source

Questions About This Research

What does the research say about auxetic structures with polymer fillings enhance energy absorption by up to 40% under dynamic impact?: When designing for impact resistance, consider using auxetic structures and explore the use of strain-rate sensitive polymer foams as fillers to enhance energy absorption capabilities. Evidence: Advanced Engineering Materials (2017).
Why does "Auxetic structures with polymer fillings enhance energy absorption by up to 40% under dynamic impact" matter for design?: This research offers a pathway to designing advanced protective materials and impact-absorbing components. By understanding how different fillings interact with auxetic geometries under dynamic loads, designers can create more effective solutions for applications requiring high energy dissipation.
How can designers apply this research?: When designing for impact resistance, consider using auxetic structures and explore the use of strain-rate sensitive polymer foams as fillers to enhance energy absorption capabilities.
What were the main findings?: Polyurethane foam filling increased specific absorbed energy by 5-40% compared to unfilled auxetic structures under dynamic impact.. Ordnance gelatine filling resulted in a 5-10% increase in specific absorbed energy.. Both the auxetic structures and the filler materials exhibited strain-rate dependent properties.. Filling influenced the achievable negative Poisson's ratio values.
What research method was used?: Experimental testing and simulation.
How strong is the evidence?: Evidence strength is rated Strong effect, based on a 2017 journal from Advanced Engineering Materials.
What should I do differently in my next project?: Investigate the use of auxetic core structures filled with specific viscoelastic foams for applications such as protective padding, vehicle impact absorption, or sports equipment.
What are the limitations?: The study focused on specific types of auxetic structures and polymer fillers; performance may vary with different geometries, materials, and filling densities. The testing was limited to compression loading.