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发表于 2010-6-23 15:21:51
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铸铝的想法是正确的。
这个方面我做过几个数学模拟模型，我就简单解释一下。
众所周知，根据Newton 3rd Law (牛顿第三定律): The mutual forces of action and reaction between two bodies are equal, opposite and collinear. This means that whenever a first body exerts a force F on a second body, the second body exerts a force −F on the first body. F and −F are equal in magnitude and opposite in direction. This law is sometimes referred to as the action-reaction law, with F called the "action" and −F the "reaction".
可以得知，当琴弦以Nut 和saddle为端点震动的时候，琴体和琴颈会受到大小相同方向相反的“作用力”。
因此对于琴的材料的考虑应该从材料的Elasticity来考虑，而并不是单纯的局限于木材。
我看过一篇从Kettering University来的的论文，是关于琴体震动方式的，其中提到了琴体的4中基本震动方式：
1. The first mode of vibration occurs at 55 Hz, and appears to be a simple bending mode. The entire guitar behaves much like a free-free beam vibrating in its fundamental mode. There are two nodal lines (places where the guitar does not move) - one is near the free end of the neck, and the other is close to the middle of the body. （粗略翻译：第一种震动模型是一种在55HZ下的简单弯曲模型。整个吉他的行为更像是free-free beam（这里应该指的是光束双自由端点传播时所产生的上下自由曲线的震动），有两个固定线？（不知道中文怎么说），一个在琴颈的Free end，一个在接近琴体的中央。）
解释：简单来说就是上平面(surface)稳定地上下摆动，无扭曲。两个nodal lines其实指的是Nut 和Bridge，即琴弦有效震动范围。
2. The second mode of vibration occurs at 160 Hz, and looks like the second free-free bending mode. Again there is a close similarity to the second mode of a free-free beam. （粗略翻译：第二个是160HZ下的模型，（后面的句子指的是图片，这里就不翻译了））
解释：琴体上下摆动，琴颈左右扭曲和上下摆动复合震动。
3. A torsional mode occurs at 372 Hz, and is a torsional mode. This is most clearly seen in the vibration of the body - opposite corners move together in phase as if the body were twisting. Nodal lines roughly split the body into four equal parts. The neck exhibits both bending and twisting motions. （粗略翻译：在372HZ时，模型为扭曲模型。可以很清楚地看到琴体的震动 - 当琴体扭曲时琴体对角点同时同频率运动。固定线粗略地将琴体分割为4个大致相等的部分。琴颈同时具有弯曲和扭曲的运动。）
解释：看翻译，基本都解释了。
4. At 472 Hz there is a bending mode in which the body of the guitar bends along its width. Then neck also bends along its length. (粗略翻译：在472HZ时，存在一个琴体沿着其宽度线弯曲的弯曲形式。琴颈也沿着其长度线摆动。)
解释：同翻译。
综上所述，我一直坚信，好音色并不是由材料决定的。理论上来说任何材料都可以产生各有特色的音色，关键问题在于其结构架设，及琴体琴颈的设计。震动当然肯定不是越大越好，如何进行平衡，在材料的弹性和弹性阻力之间取舍，以及质点及震动固定点的分配，才是真正应该思考的。
中文写得不好，将就看吧。
[ 本帖最后由 晓月 于 2010-6-23 17:24 编辑 ] |
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做琴体应该不难 ~！！！ 会不会很重啊？
