Influence of the force applied and its period of application on the outcome of the flexion test of the distal forelimb of the horse
The influence of the force applied and its period of application on the outcome of the flexion test of the distal forelimb was investigated in a group of eight sound horses. The degree of lameness after the flexion test was scored by a standard clinical classification, and by measuring the angle of maximum fetlock extension by means of the infrared light-based MacReflex gait analysis system. There was a good correlation between the clinical score and this electronically recorded kinematic parameter (r = 0.96). Both the force applied and the period of application affected the outcome of the test. Increasing the force applied by 25 per cent led to three horses being judged positive, instead of two when the normal force was applied. Doubling the time to 120 seconds resulted in four horses rather than two being classified as lame after the test. Reducing the force to 75 per cent or the time to 30 seconds resulted in all the horses being classified as sound. A flexion test lasting five minutes, either at 100 per cent force or at 75 per cent, classified six of the eight horses as lame. It is concluded that the flexion test should be defined more precisely in terms of these two factors in order to make its results more consistent and hence more useful.
Omasal and abomasal impaction in beef suckler cows
A group of late gestation suckler cows were housed in straw yards and had been fed solely on pea haulm for the previous three weeks. Four cows became ill, with a variety of clinical signs, two died, one was euthanased and one recovered spontaneously. Postmortem examination revealed severe omasal and abomasal impaction. No further cases occurred after changes were made to the diet of the cows.
Damage initiation and propagation in composite shells subjected to impact
Abstract The paper investigates the impact-induced damage initiation and propagation for laminated composite shells under low-velocity impact. A three-dimensional eight-node non-conforming element is described to analyze interlaminar stress distribution, and progressive failure. The damage analysis is performed by using Tsai–Wu quadratic failure criterion, Tsai’s damage modes and an additional delamination formula at all Gaussian points. The damage modes considered are matrix cracking, fiber breakage and delamination. The progressive failure is expressed by reducing stiffness of the material at all failed Gaussian points. Special attention is centered on curved laminates. Impact energy threshold for the onset of damage and transient damage size are predicted for composite shells. The analyses of the flat and curved laminates are compared for discussing their different damage mechanism. In addition, the influence of the stacking sequence, the thickness and the radius of curvature on damage behavior of composite shells are studied.