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BACKGROUND: Domestic and foreign scholars have done a lot of researches on the stress of articular cartilage under different mechanical environments and cyclic compressive loads, but they mainly studied the effect of cartilage under the cyclic compressive load. Studies on the effects of age factor on the mechanical properties of cartilage and studies regarding the properties of cartilage in complex stress environments are not exhaustive. OBJECTIVE: To investigate the effects of different rolling load conditions on the ratcheting behavior of adult and juvenile articular cartilage. METHODS: Adult cartilage and juvenile cartilage were used as experimental objects, and the load was applied by a rolling load device under different experimental conditions (compression: 10%, 20%, 30%; rolling rate: 1.66, 3.44, 6.68 mm/s; defect width: 1, 2,4 mm). At the same time, non-contact digital technology was used to collect the sample during the loading process, and the cyclical pressure was studied by analyzing and processing the image. The ratcheting behavior of adult and juvenile articular cartilage was studied under rolling load. RESULTS AND CONCLUSION: Under rolling load, the ratcheting strain of adult cartilage and juvenile cartilage showed a rapid increase followed by a slow increase tendency with the rolling load. With the increase of compression, the ratcheting strain of adult cartilage and juvenile cartilage increased. At the same amount of compression, the ratcheting strain of juvenile cartilage was greater than that of adult cartilage, and their ratcheting strain gradually decreased from the surface layer to the deep layer along the depth of cartilage. As the rolling rate increased, the ratcheting strain of adult cartilage and juvenile cartilage decreased. The ratcheting strain values and trends of 1 mm microdefect articular cartilage were similar to those of intact articular cartilage. Under the condition of 2,4 mm defect, the ratcheting strain value of the defected cartilage was higher than that of the intact cartilage.
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Objective To study the ratcheting behavior of defective cartilage under cyclic compressive loading, so as to explore the pattern of damage evolution for defective articular cartilage. Methods Fresh articular cartilage was obtained from the distal femur of adult porcine, and the cartilage samples with different depth of defect were applied under triangular wave cyclic loading with different parameters. Combined with non-contact digital image technology, the ratcheting strain at different layers of cartilage was obtained. Results With the increase of loading cycles numbers, the ratcheting strain at each layer of cartilage increased sharply at first, then increased slowly and tended to be stable, and the ratcheting strain decreased gradually from shallow layer to deep layer. The response of each layer to cycle number was different. The strain in shallow layer increased rapidly within 50 cycles, while the strain in middle layer increased rapidly within 100 cycles and the strain in deep layer increased rapidly within 75 cycles. The ratcheting strain in shallow and deep layers was positively correlated with the stress amplitude and defect depth, and negatively correlated with the loading rate, while hysteresis response occurreds in middle layer. Conclusions The ratcheting behavior of cartilage was affected by special structure of the cartilage. The defect caused the strain increasing in each layer of cartilage, which could easily result in the aggravation of damage. The experiment results provide references for the construction of tissue-engineered cartilage.
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Objective To obtain the ratcheting strain of articular cartilage under different loading conditions,and construct the theoretical model so as to predict the ratcheting strain of cartilage.Methods The fresh articular cartilage obtained from the trochlear of distal femur was used as experimental subject.The ratcheting strain of articular cartilage was tested under cyclic compressive loads by applying the non-contact digital image correlation technique.The theoretical model was constructed to predict the ratcheting strain of articular cartilage with different stress amplitudes and stress rates.The results from predictions were compared with the experimental results.Results The ratcheting strain of cartilage increased rapidly at initial stage and then showed the slower increase with cycles increasing.The ratcheting strain increased with stress amplitude increasing when the stress rate was constant.However,the ratcheting strain decreased with stress rate increasing when the stress amplitude was constant.When the stress rate increased,the ratcheting stain decreased.The prediction results of the established theoretical model were in good agreement with experimental results.Conclusions The ratcheting strain of articular cartilage is proportional to the stress amplitude,and inversely proportional to the stress rate.The established theoretical model can predict the ratcheting strain of articular cartilage and provide guidance for the construction of tissue engineered artificial cartilage.
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Objective To obtain the ratcheting strain of articular cartilage under different loading conditions,and construct the theoretical model so as to predict the ratcheting strain of cartilage.Methods The fresh articular cartilage obtained from the trochlear of distal femur was used as experimental subject.The ratcheting strain of articular cartilage was tested under cyclic compressive loads by applying the non-contact digital image correlation technique.The theoretical model was constructed to predict the ratcheting strain of articular cartilage with different stress amplitudes and stress rates.The results from predictions were compared with the experimental results.Results The ratcheting strain of cartilage increased rapidly at initial stage and then showed the slower increase with cycles increasing.The ratcheting strain increased with stress amplitude increasing when the stress rate was constant.However,the ratcheting strain decreased with stress rate increasing when the stress amplitude was constant.When the stress rate increased,the ratcheting stain decreased.The prediction results of the established theoretical model were in good agreement with experimental results.Conclusions The ratcheting strain of articular cartilage is proportional to the stress amplitude,and inversely proportional to the stress rate.The established theoretical model can predict the ratcheting strain of articular cartilage and provide guidance for the construction of tissue engineered artificial cartilage.
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Objective To obtain the ratcheting strain of articular cartilage under different loading conditions, and construct the theoretical model so as to predict the ratcheting strain of cartilage. Methods The fresh articular cartilage obtained from the trochlear of distal femur was used as experimental subject. The ratcheting strain of articular cartilage was tested under cyclic compressive loads by applying the non-contact digital image correlation technique. The theoretical model was constructed to predict the ratcheting strain of articular cartilage with different stress amplitudes and stress rates. The results from predictions were compared with the experimental results. Results The ratcheting strain of cartilage increased rapidly at initial stage and then showed the slower increase with cycles increasing. The ratcheting strain increased with stress amplitude increasing when the stress rate was constant. However, the ratcheting strain decreased with stress rate increasing when the stress amplitude was constant. When the stress rate increased, the ratcheting stain decreased. The prediction results of the established theoretical model were in good agreement with experimental results. Conclusions The ratcheting strain of articular cartilage is proportional to the stress amplitude, and inversely proportional to the stress rate. The established theoretical model can predict the ratcheting strain of articular cartilage and provide guidance for the construction of tissue engineered artificial cartilage.
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Objective To obtain the ratcheting strain of articular cartilage under different loading conditions,and construct the theoretical model so as to predict the ratcheting strain of cartilage.Methods The fresh articular cartilage obtained from the trochlear of distal femur was used as experimental subject.The ratcheting strain of articular cartilage was tested under cyclic compressive loads by applying the non-contact digital image correlation technique.The theoretical model was constructed to predict the ratcheting strain of articular cartilage with different stress amplitudes and stress rates.The results from predictions were compared with the experimental results.Results The ratcheting strain of cartilage increased rapidly at initial stage and then showed the slower increase with cycles increasing.The ratcheting strain increased with stress amplitude increasing when the stress rate was constant.However,the ratcheting strain decreased with stress rate increasing when the stress amplitude was constant.When the stress rate increased,the ratcheting stain decreased.The prediction results of the established theoretical model were in good agreement with experimental results.Conclusions The ratcheting strain of articular cartilage is proportional to the stress amplitude,and inversely proportional to the stress rate.The established theoretical model can predict the ratcheting strain of articular cartilage and provide guidance for the construction of tissue engineered artificial cartilage.
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Objective To investigate and evaluate the biomechanical property of the skin in pig's back in order to provide the essential theoretical basis for clinical and skin products.Method Taking the skin in pig's back as experimental material,the monotonic tensile and cyclic tension-tension tests with difierent loading rates was researohed respectivaly.Meanwhile,with different loading directions and stress levels the creep and cy-clic tension-tension tests were also been studied experimentally.Result The capacity of resisting tensile,creep and cyclic deformation of pig's skin in the direction along the Langer's line is stronger than that perpen-dicuiar to the Langer's line.The creep curve of pig's skin is load-dependent and consisted of three phases a-bout deceleration phase,stabilization phase and destruction stage.Pig's skin exhibits apparent ratcheting un-der asymmetry stress cycle.Ratcheting deformation displays significant mean stress,stress amplitude and loading speed dependence.Condusion Based on the experiment,the biomechanics property of skin's vis-coelasticity and anisotropic feature have been sysmarie stadied,it's provide necessaw theoretical fundation for clinical and leather products.
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Objective To investigate and evaluate the biomechanical property of the skin in pig's back in order to provide the essential theoretical basis for clinical and skin products.Method Taking the skin in pig's back as experimental material,the monotonic tensile and cyclic tension-tension tests with difierent loading rates was researohed respectivaly.Meanwhile,with different loading directions and stress levels the creep and cy-clic tension-tension tests were also been studied experimentally.Result The capacity of resisting tensile,creep and cyclic deformation of pig's skin in the direction along the Langer's line is stronger than that perpen-dicuiar to the Langer's line.The creep curve of pig's skin is load-dependent and consisted of three phases a-bout deceleration phase,stabilization phase and destruction stage.Pig's skin exhibits apparent ratcheting un-der asymmetry stress cycle.Ratcheting deformation displays significant mean stress,stress amplitude and loading speed dependence.Condusion Based on the experiment,the biomechanics property of skin's vis-coelasticity and anisotropic feature have been sysmarie stadied,it's provide necessaw theoretical fundation for clinical and leather products.
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Objective To investigate and evaluate the biomechanical property of the skin in pig's back in order to provide the essential theoretical basis for clinical and skin products.Method Taking the skin in pig's back as experimental material,the monotonic tensile and cyclic tension-tension tests with difierent loading rates was researohed respectivaly.Meanwhile,with different loading directions and stress levels the creep and cy-clic tension-tension tests were also been studied experimentally.Result The capacity of resisting tensile,creep and cyclic deformation of pig's skin in the direction along the Langer's line is stronger than that perpen-dicuiar to the Langer's line.The creep curve of pig's skin is load-dependent and consisted of three phases a-bout deceleration phase,stabilization phase and destruction stage.Pig's skin exhibits apparent ratcheting un-der asymmetry stress cycle.Ratcheting deformation displays significant mean stress,stress amplitude and loading speed dependence.Condusion Based on the experiment,the biomechanics property of skin's vis-coelasticity and anisotropic feature have been sysmarie stadied,it's provide necessaw theoretical fundation for clinical and leather products.