To advertise in this section contact
Peter Britton on 01747 855335 email:
peter@pitchcare.com
Surface Strength Classifieds GIVE ME STRENGTH! AERATION
TERRAIN Turf and Trees
10” drill aeration 1m air injection 1m soil coring Air excavation
www.terrainaeration.com terrainaeration@aol.com
DRAINING 25 years in
WORTH
sports turf maintenance Verti-draining
Overseeding - Sanding Top Dressing Hollow Coring
Blec Groundbreaker
Tel/Fax 01476 550266 Mobile: 07855 431119/20
email:
worthdraining@talktalk.net www.worthdraining.co.uk
AERATORS
Full range of Groundsman pedestrian and tractor mounted models with all accessories
SALES AND HIRE
Contact Synergy Products on 01380 828337
Dave on mobile: 07971 843802 Email:
sales@synergyproducts.co.uk www.synergyproducts.co.uk
ARTIFICIAL
Why not visit our on-line Buyers Guide for direct links to suppliers websites -
www.pitchcare.com
Tel: 01449 673783 DST Device
Surface Strength and Stress-Strain Behaviour - Improving testing and understanding
directly governs player-surface interaction aspects, such as the impact absorption that players will feel when running or landing on a surface, and the traction they can obtain with studded footwear. Surface strength also contributes to ball-surface interaction aspects, such as ball bounce and ball roll. Quantification of the strength of natural turf winter games pitches, and understanding of surface performance, is an area that requires greater research. This has been highlighted due to the recent concentration of media attention on high-profile player injuries, and failed sporting movements that have been attributed to surface condition.
T
under Performance Quality Standards (PQS) to assess surface strength: the Clegg Hammer, which measures the vertical strength of the surface to a falling 0.5kg or 2.25kg missile and the studded disc apparatus that measures the torque required to horizontally rotate a loaded (46kg) studded disc on the surface. These two devices have been at
the forefront of research into natural turf surfaces for over twenty years, and have aided in improving surface quality and providing a means to benchmark surface characteristics. Although these devices are relatively cheap and, in the case of the Clegg Hammer, portable to use, there are drawbacks to using these to increase our understanding of surface performance:
Advertising in this classified section costs as little as £200 a year. Telephone: 01747 855335
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• Using the studded disc apparatus to assess a pitch takes a long time, and involves the use of laborious equipment (46kg of weight). This restricts data being collected from pitches regularly (e.g. on a daily basis), or across a large number of pitches.
• The devices do not represent how a player interacts with the surface. This has limited our understanding of how the
There are two devices used
he strength of natural turf winter games pitches is a surface characteristic that
surface reacts to being loaded by players, and what the players experience back from the surface (energy absorption/return and traction).
In recent years, advanced research at Cranfield and Exeter Universities has enhanced the understanding of how players interact with sports surfaces. This area of research requires studying surface stress-strain behaviour - quantifying the reaction of the surface to being stressed. While measuring strength provides data on the maximum stress a surface can withstand before it fails (deforms), stress-strain behaviour is concerned with quantifying ratios of permanent (plastic) and recoverable (elastic) deformation the surface exhibits when it is loaded. These aspects determine the amount of energy that will be absorbed or returned by the surface when impacted by a player or ball.
understand that the strength exhibited by soil-turf surfaces is dependent upon the speed at which it is loaded (loading rate). Increasing the loading rate of a force acting on soil results in the soil exhibiting greater strength. When soils are stressed slowly (e.g. by pushing a stick into the ground), the soil particles have time to move and provide surface deformation but, when they are loaded quickly, the particles do not have time to move, and exhibit greater strength by deforming less. Modelling of player impacts upon soil has shown that the faster the soil is loaded, the more elastic the soil behaves. This elasticity was also found to be higher on sand soils compared to more clayey soils, and it is important to understand this loading rate dependency of natural turf when considering what effect the player has on the surface, or vice-versa. Relating the strength and stress- strain behaviour of a surface to specific injury risks, or performance potential for players, is very difficult, due to their being a lack of devices that directly
It is also important to
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