How to determine the optimal curvature and tilt angle of the lounge chair backrest?

Determining the optimal curvature and tilt angle of the lounge chair backrest involves multiple considerations, including ergonomics, user comfort, usage scenarios, and design and manufacturing feasibility. Here are some key steps and methods:

Ergonomic analysis
Natural spine curve: Understand the natural curve of the human spine, especially the curvature of the lumbar and thoracic spine. The ideal backrest design should mimic these natural curves to provide the best support.
Sitting study: Analyze the back pressure distribution and spinal morphology under different sitting postures. Common sitting postures include upright sitting, relaxed sitting, and semi-lying posture.

User comfort survey
User feedback: Through surveys and tests, collect user feedback on different backrest curvatures and tilt angles. Understand the user's comfort and support when using the lounge chair for a long time.
Simulation test: Let users sit on the prototype chair for a long time and record their comfort and fatigue. Pressure sensors can be used to monitor the pressure distribution in different areas of the back.

Experimental data and analysis
Pressure distribution test: Use a pressure distribution tester to measure the support effect of the backrest on the back at different curvatures and inclination angles. The ideal design should provide uniform support in all areas of the back and reduce pressure concentration.
Biomechanical modeling: Through computer simulation and biomechanical modeling, analyze the effects of backrests of different designs on the spine and back muscles. Optimize the curvature and inclination angle of the backrest to reduce muscle tension and spinal pressure.

Determination of design parameters
Backrest curvature: The lower part of the backrest should bend forward to support the waist, and the recommended curvature is usually between 100° and 110°. The middle and upper parts of the backrest should be slightly tilted backward to accommodate the natural curves of the thoracic spine and upper back.
Tilt angle: The inclination angle of the backrest is generally between 90° and 135°. For a relaxing lounge chair, a larger inclination angle, such as 110° to 130°, can be considered. The adjustable backrest design allows users to adjust the angle according to personal needs and provide greater comfort.

Prototype testing and optimization
Prototype making: Make a lounge chair prototype according to the preliminary design parameters, and conduct actual testing and evaluation.
User testing: Invite target users to test and record their comfort, support and fatigue. Adjust the curvature and tilt angle of the backrest according to the feedback data.
Repeated optimization: Through repeated testing and optimization, continuously improve the design to ensure that the final product achieves the best results in terms of comfort and support.

Final design verification
Long-term use test: Conduct long-term use tests to ensure that the backrest design remains comfortable and supportive during long-term use.
Diversified testing: Test in different environments and different user groups to ensure the universality and wide applicability of the design.
Comprehensive evaluation: Comprehensively consider user feedback, experimental data and manufacturing feasibility to determine the final backrest curvature and tilt angle design.

Through these steps and methods, the optimal curvature and tilt angle of the lounge chair backrest can be scientifically determined to ensure the comfort and support of the design to meet the needs of different users.